Patent Publication Number: US-2022229864-A1

Title: Multimedia Content Distribution System and Method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/952,217 titled “Multimedia Content Distribution System and Method,” filed on Nov. 19, 2020, and currently pending; U.S. application Ser. No. 16/952,217 is a continuation of U.S. application Ser. No. 14/297,193 titled “Social Queue,” filed on Jun. 5, 2014, and now abandoned. The entire contents of U.S. application Ser. Nos. 16/952,217 and 14/297,193 are incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The disclosure is related to consumer goods and, more particularly, to methods, systems, products, features, services, and other elements directed to media playback or some aspect thereof. 
     BACKGROUND 
     Options for accessing and listening to digital audio in an out-loud setting were limited until in 2003, when SONOS, Inc. filed for one of its first patent applications, entitled “Method for Synchronizing Audio Playback between Multiple Networked Devices,” and began offering a media playback system for sale in 2005. The Sonos Wireless HiFi System enables people to experience music from many sources via one or more networked playback devices. Through a software control application installed on a smartphone, tablet, or computer, one can play what he or she wants in any room that has a networked playback device. Additionally, using the controller, for example, different songs can be streamed to each room with a playback device, rooms can be grouped together for synchronous playback, or the same song can be heard in all rooms synchronously. 
     Given the ever growing interest in digital media, there continues to be a need to develop consumer-accessible technologies to further enhance the listening experience. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, aspects, and advantages of the presently disclosed technology may be better understood with regard to the following description, appended claims, and accompanying drawings where: 
         FIG. 1  shows an example media playback system configuration in which certain embodiments may be practiced; 
         FIG. 2  shows a functional block diagram of an example playback device; 
         FIG. 3  shows a functional block diagram of an example control device; 
         FIG. 4  shows an example controller interface; 
         FIG. 5  shows a functional block diagram of an example computing device; 
         FIG. 6  is a simplified representation of an example system for cloud computing; 
         FIG. 7  shows an example environment in which the present methods may be implemented; 
         FIG. 8  shows an example flow diagram for generating a social queue; 
         FIG. 9  shows an example flow diagram to facilitate a social queue for use by a group of media playback systems; 
         FIG. 10  shows a second example flow diagram to facilitate a social queue for use by a group of media playback systems; 
         FIGS. 11A and 11B  show example user interfaces to facilitate group formation; 
         FIGS. 12A and 12B  show example user interfaces to facilitate social queue interaction. 
     
    
    
     The drawings are for the purpose of illustrating example embodiments, but it is understood that the inventions are not limited to the arrangements and instrumentality shown in the drawings. 
     DETAILED DESCRIPTION 
     I. Overview 
     In some arrangements, a device within a media playback system may generate a playback queue of media items. The media playback system may then perform various operations with respect to the playback queue. For instance, the media playback system may play back media items in the playback queue. Further, input received by the media playback system may modify the playback queue by adding media items to or removing media items from the playback queue. Some such uses of the playback queue might be limited to use by the media playback system itself. 
     Examples described herein involve a “social” queue of media items for use by a group of two or more media playback systems. Media playback systems in the group may collaboratively interact with the social queue. For instance, each media playback system in the group may contribute media items to the social queue, such that the social queue includes media items contributed from multiple media playback system in the group. Further, each media playback system in the group may play back the media items in the social queue. 
     In one example, a group of media playback systems may include a first media playback system and a second media playback system. The first media playback system and the second media playback system may be in different locations, such as at a first user&#39;s home or workplace and at a second user&#39;s home or workplace, respectively. The first media playback system may communicate with the second media playback system over a network, such as the Internet. A first control device of the first media playback system may create, access, and modify the social queue. Likewise, a second control device of the second media playback system may create, access, and modify the social queue. Further, the first control device and the second control device may cause playback of media items in the social queue at one or more first playback devices of the first media playback system and one or more second playback devices of the second media playback system, respectively. In this way, the first control device and the second control device may facilitate collaborative interaction to control playback of media items at their respective media playback systems by interaction with the social queue. 
     As members of a group, the first media playback system and the second media playback system may have certain defined relationships with one another. They may share information, such as media items to add to the social queue or an indication of whether the media system is presently accessing the social queue. Further, they may operate according to one or more group rules. One group rule may require the first media playback system and the second media playback system to have access to one or more of the same audio content sources, to facilitate access by both media playback systems to media playback items in the social queue. Many other examples of information sharing and group rules are possible as well. 
     In some cases, a cloud service, such as a social networking service, may facilitate group formation and use of the social queue. For instance, a social networking service may provide an interface for selecting media playback systems for grouping. Such selectable media playback systems may be registered to users with whom the particular user of the social networking service has formed connections within the social networking service. For example, the a media playback system registered to a particular user may offer to group with media playback systems of one or more of the user&#39;s “friends” on a social networking service. The interface of the social networking service may also provide transport controls for causing playback of the social queue on the media playback system and media selection controls for selecting media items to add to the social queue. 
     As indicated above, the present application involves a social queue for a group of media playback systems. In one aspect, a method is provided. The method involves receiving, from a first media playback system, a first message indicating a first set of media items and receiving, from a second media playback system, a second message indicating a second set of media items. The method also involves generating a playback queue comprising the first set of media items indicated in the first message and the second set of media items indicated in the second message. The method further involves transmitting, to at least one of the first media playback system and the second media playback system, the generated playback queue. 
     In another aspect, a device is provided. The device includes a processor, a network interface, a non-transitory computer-readable storage medium, and program logic stored on the non-transitory computer-readable medium and executable by the processor to perform functions. The functions include receiving, from a first media playback system, a first message indicating a first set of media items and receiving, from a second media playback system, a second message indicating a second set of media items. The functions also include generating a playback queue comprising the first set of media items indicated in the first message and the second set of media items indicated in the second message. The functions further include transmitting, to at least one of the first media playback system and the second media playback system, the generated playback queue. 
     In yet another aspect, a non-transitory computer readable memory is provided. The non-transitory computer readable memory has stored thereon instructions executable by a computing device to cause the computing device to perform functions. The functions include receiving, from a first media playback system, a first message indicating a first set of media items and receiving, from a second media playback system, a second message indicating a second set of media items. The functions also include generating a playback queue comprising the first set of media items indicated in the first message and the second set of media items indicated in the second message. The functions further include transmitting, to at least one of the first media playback system and the second media playback system, the generated playback queue. 
     In another aspect, a method is provided. The method involves receiving, at a computing device associated with a first media playback system, a command to form a group of media playback systems that comprises the first media playback system and at least one other media playback system. The method also involves receiving, at the computing device, an identification of at least one source of audio for playback by the group of media playback systems. The method further involve sending, by the computing device to the at least one other media playback system, a message comprising (i) an indication of the received command to form the group of media playback systems and (ii) an indication of the at least one source of audio for playback by the group of media playback systems. 
     In yet another aspect, a device is provided. The device includes a processor, a network interface, a non-transitory computer-readable storage medium, and program logic stored on the non-transitory computer-readable medium and executable by the processor to perform functions. The functions include receiving, at a computing device associated with a first media playback system, a command to form a group of media playback systems that comprises the first media playback system and at least one other media playback system. The function also include receiving, at the computing device, an identification of at least one source of audio for playback by the group of media playback systems. The functions further include sending, by the computing device to the at least one other media playback system, a message comprising (i) an indication of the received command to form the group of media playback systems and (ii) an indication of the at least one source of audio for playback by the group of media playback systems. 
     In another aspect, a non-transitory computer readable memory is provided. The non-transitory computer readable memory has stored thereon instructions executable by a computing device to cause the computing device to perform functions. The functions include receiving, at a computing device associated with a first media playback system, a command to form a group of media playback systems that comprises the first media playback system and at least one other media playback system. The function also include receiving, at the computing device, an identification of at least one source of audio for playback by the group of media playback systems. The functions further include sending, by the computing device to the at least one other media playback system, a message comprising (i) an indication of the received command to form the group of media playback systems and (ii) an indication of the at least one source of audio for playback by the group of media playback systems. 
     In yet one aspect, a method is provided. The method involves receiving an instruction that causes at least a first media playback system and a second media playback system to form a group of media playback systems. The method also involves receiving, from a third-party service provider, a first message indicating a first set of media items and a second message indicating a second set of media items. The method further involves generating a playback queue comprising the first set of media items indicated in the received first message and the second set of media items indicated in the received second message. The method also involves transmitting, to each media playback system in the group of media playback system, the generated playback queue. 
     In another aspect, a device is provided. The device includes a processor, a network interface, a non-transitory computer-readable storage medium, and program logic stored on the non-transitory computer-readable medium and executable by the processor to perform functions. The functions include receiving an instruction that causes at least a first media playback system and a second media playback system to form a group of media playback systems. The functions also include receiving, from a third-party service provider, a first message indicating a first set of media items and a second message indicating a second set of media items. The functions further include generating a playback queue comprising the first set of media items indicated in the received first message and the second set of media items indicated in the received second message. The functions also include transmitting, to each media playback system in the group of media playback system, the generated playback queue. 
     In yet another aspect, a non-transitory computer readable memory is provided. The non-transitory computer readable memory has stored thereon instructions executable by a computing device to cause the computing device to perform functions. The functions include receiving an instruction that causes at least a first media playback system and a second media playback system to form a group of media playback systems. The functions also include receiving, from a third-party service provider, a first message indicating a first set of media items and a second message indicating a second set of media items. The functions further include generating a playback queue comprising the first set of media items indicated in the received first message and the second set of media items indicated in the received second message. The functions also include transmitting, to each media playback system in the group of media playback system, the generated playback queue. 
     It will be understood by one of ordinary skill in the art that this disclosure includes numerous other embodiments. While some examples described herein may refer to functions performed by given actors such as “users” and/or other entities, it should be understood that this description is for purposes of explanation only. The claims should not be interpreted to require action by any such example actor unless explicitly required by the language of the claims themselves. 
     II. Example Operating Environment 
       FIG. 1  shows an example configuration of a media playback system  100  in which one or more embodiments disclosed herein may be practiced or implemented. The media playback system  100  as shown is associated with an example home environment having several rooms and spaces, such as for example, a master bedroom, an office, a dining room, and a living room. As shown in the example of  FIG. 1 , the media playback system  100  includes playback devices  102 - 124 , control devices  126  and  128 , and a wired or wireless network router  130 . 
     Further discussions relating to the different components of the example media playback system  100  and how the different components may interact to provide a user with a media experience may be found in the following sections. While discussions herein may generally refer to the example media playback system  100 , technologies described herein are not limited to applications within, among other things, the home environment as shown in  FIG. 1 . For instance, the technologies described herein may be useful in environments where multi-zone audio may be desired, such as, for example, a commercial setting like a restaurant, mall or airport, a vehicle like a sports utility vehicle (SUV), bus or car, a ship or boat, an airplane, and so on. 
     a. Example Playback Devices 
       FIG. 2  shows a functional block diagram of an example playback device  200  that may be configured to be one or more of the playback devices  102 - 124  of the media playback system  100  of  FIG. 1 . The playback device  200  may include a processor  202 , software components  204 , memory  206 , audio processing components  208 , audio amplifier(s)  210 , speaker(s)  212 , and a network interface  214  including wireless interface(s)  216  and wired interface(s)  218 . In one case, the playback device  200  may not include the speaker(s)  212 , but rather a speaker interface for connecting the playback device  200  to external speakers. In another case, the playback device  200  may include neither the speaker(s)  212  nor the audio amplifier(s)  210 , but rather an audio interface for connecting the playback device  200  to an external audio amplifier or audio-visual receiver. 
     In one example, the processor  202  may be a clock-driven computing component configured to process input data according to instructions stored in the memory  206 . The memory  206  may be a tangible computer-readable medium configured to store instructions executable by the processor  202 . For instance, the memory  206  may be data storage that can be loaded with one or more of the software components  204  executable by the processor  202  to achieve certain functions. In one example, the functions may involve the playback device  200  retrieving audio data from an audio source or another playback device. In another example, the functions may involve the playback device  200  sending audio data to another device or playback device on a network. In yet another example, the functions may involve pairing of the playback device  200  with one or more playback devices to create a multi-channel audio environment. [ 37 ] Certain functions may involve the playback device  200  synchronizing playback of audio content with one or more other playback devices. During synchronous playback, a listener will preferably not be able to perceive time-delay differences between playback of the audio content by the playback device  200  and the one or more other playback devices. U.S. Pat. No. 8,234,395 entitled, “System and method for synchronizing operations among a plurality of independently clocked digital data processing devices,” which is hereby incorporated by reference, provides in more detail some examples for audio playback synchronization among playback devices. 
     The memory  206  may further be configured to store data associated with the playback device  200 , such as one or more zones and/or zone groups the playback device  200  is a part of, audio sources accessible by the playback device  200 , or a playback queue that the playback device  200  (or some other playback device) may be associated with. The data may be stored as one or more state variables that are periodically updated and used to describe the state of the playback device  200 . The memory  206  may also include the data associated with the state of the other devices of the media system, and shared from time to time among the devices so that one or more of the devices have the most recent data associated with the system. Other embodiments are also possible. 
     The audio processing components  208  may include one or more digital-to-analog converters (DAC), an audio preprocessing component, an audio enhancement component or a digital signal processor (DSP), and so on. In one embodiment, one or more of the audio processing components  208  may be a subcomponent of the processor  202 . In one example, audio content may be processed and/or intentionally altered by the audio processing components  208  to produce audio signals. The produced audio signals may then be provided to the audio amplifier(s)  210  for amplification and playback through speaker(s)  212 . Particularly, the audio amplifier(s)  210  may include devices configured to amplify audio signals to a level for driving one or more of the speakers  212 . The speaker(s)  212  may include an individual transducer (e.g., a “driver”) or a complete speaker system involving an enclosure with one or more drivers. A particular driver of the speaker(s)  212  may include, for example, a subwoofer (e.g., for low frequencies), a mid-range driver (e.g., for middle frequencies), and/or a tweeter (e.g., for high frequencies). In some cases, each transducer in the one or more speakers  212  may be driven by an individual corresponding audio amplifier of the audio amplifier(s)  210 . In addition to producing analog signals for playback by the playback device  200 , the audio processing components  208  may be configured to process audio content to be sent to one or more other playback devices for playback. 
     Audio content to be processed and/or played back by the playback device  200  may be received from an external source, such as via an audio line-in input connection (e.g., an auto-detecting 3.5 mm audio line-in connection) or the network interface  214 . 
     The network interface  214  may be configured to facilitate a data flow between the playback device  200  and one or more other devices on a data network. As such, the playback device  200  may be configured to receive audio content over the data network from one or more other playback devices in communication with the playback device  200 , network devices within a local area network, or audio content sources over a wide area network such as the Internet. In one example, the audio content and other signals transmitted and received by the playback device  200  may be transmitted in the form of digital packet data containing an Internet Protocol (IP)-based source address and IP-based destination addresses. In such a case, the network interface  214  may be configured to parse the digital packet data such that the data destined for the playback device  200  is properly received and processed by the playback device  200 . 
     As shown, the network interface  214  may include wireless interface(s)  216  and wired interface(s)  218 . The wireless interface(s)  216  may provide network interface functions for the playback device  200  to wirelessly communicate with other devices (e.g., other playback device(s), speaker(s), receiver(s), network device(s), control device(s) within a data network the playback device  200  is associated with) in accordance with a communication protocol (e.g., any wireless standard including IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4G mobile communication standard, and so on). The wired interface(s)  218  may provide network interface functions for the playback device  200  to communicate over a wired connection with other devices in accordance with a communication protocol (e.g., IEEE 802.3). While the network interface  214  shown in  FIG. 2  includes both wireless interface(s)  216  and wired interface(s)  218 , the network interface  214  may in some embodiments include only wireless interface(s) or only wired interface(s). 
     In one example, the playback device  200  and one other playback device may be paired to play two separate audio components of audio content. For instance, playback device  200  may be configured to play a left channel audio component, while the other playback device may be configured to play a right channel audio component, thereby producing or enhancing a stereo effect of the audio content. The paired playback devices (also referred to as “bonded playback devices”) may further play audio content in synchrony with other playback devices. 
     In another example, the playback device  200  may be sonically consolidated with one or more other playback devices to form a single, consolidated playback device. A consolidated playback device may be configured to process and reproduce sound differently than an unconsolidated playback device or playback devices that are paired, because a consolidated playback device may have additional speaker drivers through which audio content may be rendered. For instance, if the playback device  200  is a playback device designed to render low frequency range audio content (i.e., a subwoofer), the playback device  200  may be consolidated with a playback device designed to render full frequency range audio content. In such a case, the full frequency range playback device, when consolidated with the low frequency playback device  200 , may be configured to render only the mid and high frequency components of audio content, while the low frequency range playback device  200  renders the low frequency component of the audio content. The consolidated playback device may further be paired with a single playback device or yet another consolidated playback device. 
     By way of illustration, SONOS, Inc. presently offers (or has offered) for sale certain playback devices including a “PLAY:1,” “PLAY:3,” “PLAY:5,” “PLAYBAR,” “CONNECT:AMP,” “CONNECT,” and “SUB.” Any other past, present, and/or future playback devices may additionally or alternatively be used to implement the playback devices of example embodiments disclosed herein. Additionally, it is understood that a playback device is not limited to the example illustrated in  FIG. 2  or to the SONOS product offerings. For example, a playback device may include a wired or wireless headphone. In another example, a playback device may include or interact with a docking station for personal mobile media playback devices. In yet another example, a playback device may be integral to another device or component such as a television, a lighting fixture, or some other device for indoor or outdoor use. 
     b. Example Playback Zone Configurations 
     Referring back to the media playback system  100  of  FIG. 1 , the environment may have one or more playback zones, each with one or more playback devices. The media playback system  100  may be established with one or more playback zones, after which one or more zones may be added, or removed to arrive at the example configuration shown in  FIG. 1 . Each zone may be given a name according to a different room or space such as an office, bathroom, master bedroom, bedroom, kitchen, dining room, living room, and/or balcony. In one case, a single playback zone may include multiple rooms or spaces. In another case, a single room or space may include multiple playback zones. 
     As shown in  FIG. 1 , the balcony, dining room, kitchen, bathroom, office, and bedroom zones each have one playback device, while the living room and master bedroom zones each have multiple playback devices. In the living room zone, playback devices  104 ,  106 ,  108 , and  110  may be configured to play audio content in synchrony as individual playback devices, as one or more bonded playback devices, as one or more consolidated playback devices, or any combination thereof. Similarly, in the case of the master bedroom, playback devices  122  and  124  may be configured to play audio content in synchrony as individual playback devices, as a bonded playback device, or as a consolidated playback device. 
     In one example, one or more playback zones in the environment of  FIG. 1  may each be playing different audio content. For instance, the user may be grilling in the balcony zone and listening to hip hop music being played by the playback device  102  while another user may be preparing food in the kitchen zone and listening to classical music being played by the playback device  114 . In another example, a playback zone may play the same audio content in synchrony with another playback zone. For instance, the user may be in the office zone where the playback device  118  is playing the same rock music that is being playing by playback device  102  in the balcony zone. In such a case, playback devices  102  and  118  may be playing the rock music in synchrony such that the user may seamlessly (or at least substantially seamlessly) enjoy the audio content that is being played out-loud while moving between different playback zones. Synchronization among playback zones may be achieved in a manner similar to that of synchronization among playback devices, as described in previously referenced U.S. Pat. No. 8,234,395. 
     As suggested above, the zone configurations of the media playback system  100  may be dynamically modified, and in some embodiments, the media playback system  100  supports numerous configurations. For instance, if a user physically moves one or more playback devices to or from a zone, the media playback system  100  may be reconfigured to accommodate the change(s). For instance, if the user physically moves the playback device  102  from the balcony zone to the office zone, the office zone may now include both the playback device  118  and the playback device  102 . The playback device  102  may be paired or grouped with the office zone and/or renamed if so desired via a control device such as the control devices  126  and  128 . On the other hand, if the one or more playback devices are moved to a particular area in the home environment that is not already a playback zone, a new playback zone may be created for the particular area. 
     Further, different playback zones of the media playback system  100  may be dynamically combined into zone groups or split up into individual playback zones. For instance, the dining room zone and the kitchen zone  114  may be combined into a zone group for a dinner party such that playback devices  112  and  114  may render audio content in synchrony. On the other hand, the living room zone may be split into a television zone including playback device  104 , and a listening zone including playback devices  106 ,  108 , and  110 , if the user wishes to listen to music in the living room space while another user wishes to watch television. 
     c. Example Control Devices 
       FIG. 3  shows a functional block diagram of an example control device  300  that may be configured to be one or both of the control devices  126  and  128  of the media playback system  100 . As shown, the control device  300  may include a processor  302 , memory  304 , a network interface  306 , and a user interface  308 . In one example, the control device  300  may be a dedicated controller for the media playback system  100 . In another example, the control device  300  may be a network device on which media playback system controller application software may be installed, such as for example, an iPhone™, iPad™ or any other smart phone, tablet or network device (e.g., a networked computer such as a PC or Mac™) 
     The processor  302  may be configured to perform functions relevant to facilitating user access, control, and configuration of the media playback system  100 . The memory  304  may be configured to store instructions executable by the processor  302  to perform those functions. The memory  304  may also be configured to store the media playback system controller application software and other data associated with the media playback system  100  and the user. 
     In one example, the network interface  306  may be based on an industry standard (e.g., infrared, radio, wired standards including IEEE 802.3, wireless standards including IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4G mobile communication standard, and so on). Control device  300  may communicate with other devices in the media playback system  100  via network interface  306 . In one example, data and information (e.g., such as a state variable) may be communicated between control device  300  and other devices via the network interface  306 . For instance, playback zone and zone group configurations in the media playback system  100  may be received by the control device  300  from a playback device or another network device, or transmitted by the control device  300  to another playback device or network device via the network interface  306 . In some cases, the other network device may be another control device. 
     Playback device control commands such as volume control and audio playback control may also be communicated from the control device  300  to a playback device via the network interface  306 . As suggested above, changes to configurations of the media playback system  100  may also be performed by a user using the control device  300 . The configuration changes may include adding/removing one or more playback devices to/from a zone, adding/removing one or more zones to/from a zone group, forming a bonded or consolidated player, separating one or more playback devices from a bonded or consolidated player, among others. Accordingly, the control device  300  may sometimes be referred to as a controller, whether the control device  300  is a dedicated controller or a network device on which media playback system controller application software is installed. 
     The user interface  308  of the control device  300  may be configured to facilitate user access and control of the media playback system  100 , by providing a controller interface such as the controller interface  400  shown in  FIG. 4 . The controller interface  400  includes a playback control region  410 , a playback zone region  420 , a playback status region  430 , a playback queue region  440 , and an audio content sources region  450 . The user interface  400  as shown is just one example of a user interface that may be provided on a network device such as the control device  300  of  FIG. 3  (and/or the control devices  126  and  128  of  FIG. 1 ) and accessed by users to control a media playback system such as the media playback system  100 . Other user interfaces of varying formats, styles, and interactive sequences may alternatively be implemented on one or more network devices to provide comparable control access to a media playback system. 
     The playback control region  410  may include selectable (e.g., by way of touch or by using a cursor) icons to cause playback devices in a selected playback zone or zone group to play or pause, fast forward, rewind, skip to next, skip to previous, enter/exit shuffle mode, enter/exit repeat mode, enter/exit cross fade mode. The playback control region  410  may also include selectable icons to modify equalization settings, and playback volume, among other possibilities. 
     The playback zone region  420  may include representations of playback zones within the media playback system  100 . In some embodiments, the graphical representations of playback zones may be selectable to bring up additional selectable icons to manage or configure the playback zones in the media playback system, such as a creation of bonded zones, creation of zone groups, separation of zone groups, and renaming of zone groups, among other possibilities. 
     For example, as shown, a “group” icon may be provided within each of the graphical representations of playback zones. The “group” icon provided within a graphical representation of a particular zone may be selectable to bring up options to select one or more other zones in the media playback system to be grouped with the particular zone. Once grouped, playback devices in the zones that have been grouped with the particular zone will be configured to play audio content in synchrony with the playback device(s) in the particular zone. Analogously, a “group” icon may be provided within a graphical representation of a zone group. In this case, the “group” icon may be selectable to bring up options to deselect one or more zones in the zone group to be removed from the zone group. Other interactions and implementations for grouping and ungrouping zones via a user interface such as the user interface  400  are also possible. The representations of playback zones in the playback zone region  420  may be dynamically updated as playback zone or zone group configurations are modified. 
     The playback status region  430  may include graphical representations of audio content that is presently being played, previously played, or scheduled to play next in the selected playback zone or zone group. The selected playback zone or zone group may be visually distinguished on the user interface, such as within the playback zone region  420  and/or the playback status region  430 . The graphical representations may include track title, artist name, album name, album year, track length, and other relevant information that may be useful for the user to know when controlling the media playback system via the user interface  400 . 
     The playback queue region  440  may include graphical representations of audio content in a playback queue associated with the selected playback zone or zone group. In some embodiments, each playback zone or zone group may be associated with a playback queue containing information corresponding to zero or more audio items for playback by the playback zone or zone group. For instance, each audio item in the playback queue may comprise a uniform resource identifier (URI), a uniform resource locator (URL) or some other identifier that may be used by a playback device in the playback zone or zone group to find and/or retrieve the audio item from a local audio content source or a networked audio content source, possibly for playback by the playback device. 
     In one example, a playlist may be added to a playback queue, in which case information corresponding to each audio item in the playlist may be added to the playback queue. In another example, audio items in a playback queue may be saved as a playlist. In a further example, a playback queue may be empty, or populated but “not in use” when the playback zone or zone group is playing continuously streaming audio content, such as Internet radio that may continue to play until otherwise stopped, rather than discrete audio items that have playback durations. In an alternative embodiment, a playback queue can include Internet radio and/or other streaming audio content items and be “in use” when the playback zone or zone group is playing those items. Other examples are also possible. 
     When playback zones or zone groups are “grouped” or “ungrouped,” playback queues associated with the affected playback zones or zone groups may be cleared or re-associated. For example, if a first playback zone including a first playback queue is grouped with a second playback zone including a second playback queue, the established zone group may have an associated playback queue that is initially empty, that contains audio items from the first playback queue (such as if the second playback zone was added to the first playback zone), that contains audio items from the second playback queue (such as if the first playback zone was added to the second playback zone), or a combination of audio items from both the first and second playback queues. Subsequently, if the established zone group is ungrouped, the resulting first playback zone may be re-associated with the previous first playback queue, or be associated with a new playback queue that is empty or contains audio items from the playback queue associated with the established zone group before the established zone group was ungrouped. Similarly, the resulting second playback zone may be re-associated with the previous second playback queue, or be associated with a new playback queue that is empty, or contains audio items from the playback queue associated with the established zone group before the established zone group was ungrouped. Other examples are also possible. 
     Referring back to the user interface  400  of  FIG. 4 , the graphical representations of audio content in the playback queue region  440  may include track titles, artist names, track lengths, and other relevant information associated with the audio content in the playback queue. In one example, graphical representations of audio content may be selectable to bring up additional selectable icons to manage and/or manipulate the playback queue and/or audio content represented in the playback queue. For instance, a represented audio content may be removed from the playback queue, moved to a different position within the playback queue, or selected to be played immediately, or after any currently playing audio content, among other possibilities. A playback queue associated with a playback zone or zone group may be stored in a memory on one or more playback devices in the playback zone or zone group, on a playback device that is not in the playback zone or zone group, and/or some other designated device. 
     The audio content sources region  450  may include graphical representations of selectable audio content sources from which audio content may be retrieved and played by the selected playback zone or zone group. Discussions pertaining to audio content sources may be found in the following section. 
     d. Example Audio Content Sources 
     As indicated previously, one or more playback devices in a zone or zone group may be configured to retrieve for playback audio content (e.g., according to a corresponding URI or URL for the audio content) from a variety of available audio content sources. In one example, audio content may be retrieved by a playback device directly from a corresponding audio content source (e.g., a line-in connection). In another example, audio content may be provided to a playback device over a network via one or more other playback devices or network devices. 
     Example audio content sources may include a memory of one or more playback devices in a media playback system such as the media playback system  100  of  FIG. 1 , local music libraries on one or more network devices (such as a control device, a network-enabled personal computer, or a networked-attached storage (NAS), for example), streaming audio services providing audio content via the Internet (e.g., the cloud), or audio sources connected to the media playback system via a line-in input connection on a playback device or network devise, among other possibilities. 
     In some embodiments, audio content sources may be regularly added or removed from a media playback system such as the media playback system  100  of  FIG. 1 . In one example, an indexing of audio items may be performed whenever one or more audio content sources are added, removed or updated. Indexing of audio items may involve scanning for identifiable audio items in all folders/directory shared over a network accessible by playback devices in the media playback system, and generating or updating an audio content database containing metadata (e.g., title, artist, album, track length, among others) and other associated information, such as a URI or URL for each identifiable audio item found. Other examples for managing and maintaining audio content sources may also be possible. 
     e. Example Cloud Computing Functions 
     Various references are made herein to “cloud computing” The term “cloud computing” is used to refer to services delivered using distributed computing over a network, such as the Internet. A non-exhaustive list of services delivered via the cloud include electronic mail (e.g., Gmail® or Hotmail®), social networking (e.g., Facebook®, LinkedIn®, or Twitter®), file hosting (e.g., Dropbox®), and streaming audio (e.g., Spotify®, Pandora®, or BeatsAudio®). Other cloud services are certainly offered as well. 
     Cloud service providers may offer one or more interfaces for accessing their service over a network. For instance, some cloud services may be accessed by visiting a web site using a web browser. Other cloud services are accessed by executing a particular application specific to the cloud service on a computing device. Some cloud services may offer an application programming interface (API) to facilitate access to the service by a third-party web site or application. In many cases, a user who has access to a given cloud service can access the service from any computing device that is connected to the network, provided that the computing device has a supported interface to the cloud service. 
     In one instance, accessing a cloud service may involve accessing, with a first computing device (i.e., a client), a second computing device (i.e., a server). Example client devices may include playback device  200  of  FIG. 2 , or control device  300  of  FIG. 3 , among other possible devices. One or more programs or applications (i.e., instructions) may execute on the server to perform computing tasks supported by the cloud service. The client may send various commands to the server to instruct the server to perform the computing tasks supported by the cloud service. 
       FIG. 5  illustrates an example computing device  500  that may provide a cloud service to one or more users. Example computing device  500  includes at least one processor  502 , memory  504 , and a network interface  506 . The memory  504  may contain instructions executable by the processor  502  to perform computing tasks supported by a cloud service. The computing device  500  may communicate with other computing devices via the network interface  506 . 
     In aggregate, the provision of a cloud service many involve multiple instances of computing device  500 . Each instance of computing device  500  may provide the cloud service to one or more users. Cloud service providers may scale the number of instances of computing device  500  involved in providing the cloud service based on user demand. 
       FIG. 6  illustrates an example cloud  600 . The example cloud  600  may include any number of computing devices which are interconnected via one or more networks. For instance, cloud  600  may include one or more instances of computing device  500 . As shown in  FIG. 6 , media playback systems  610  and  620  are connected to cloud  600 . In particular, media playback system  610  includes playback devices  612  and  614  and control device  616 , each having a respective connection to cloud  600 . Likewise, media playback system  620  includes playback devices  622  and  624  and control device  626 , each having a respective connection to cloud  600 . 
     Using the cloud  600 , media playback systems  610  and  620  may access various cloud services. For example, a cloud service provider may provide one or more first-party services  602 . In one instance, a manufacturer of media playback systems  610  and  620  may provide the one or more first-party services  602  to media playback systems  610  and  620 . The one or more first-party services  602  may support various features of the media playback systems  610  and  620 . Alternatively, another cloud service provider may provide the one or more first-party services  602  to media playback systems  610  and  620  under the direction of the manufacturer of media playback systems  610  and  620 . 
     Media playback systems  610  and  620  may also access one or more streaming audio services  604 . As noted above, streaming audio services may provide audio content to media playback systems. Several example streaming audio services that are currently available include Spotify®, Pandora®, BeatsAudio®, Radio®, Google Play Music All Access®, Sony Music Unlimited®, iTunes Radio®, Xbox Music®, and TuneIn Radio®. Other streaming audio services certainly exist, and other streaming audio services may be offered in the future. 
     Media playback systems  610  and  620  may also access one or more social network services  606 . Social network services are often characterized at least in part by various links between users of the service. Such links are referred to by different names, such as “friends”, “connections”, “followers”, or “favorites,” among other examples. Users may create such links for various reasons. For instance, in some cases, the users may have a relationship outside of the social network (e.g., co-workers, relatives, or college friends). In other cases, two users may have similar interests (e.g., fans of a particular band or genre) or belong to a certain group and then form a link in the social network because they share these similar interests. 
     Social network services may provide access to various other cloud services. For instance, a social network service may provide an interface for accessing a streaming audio service. Such an interface may include transport controls controlling play back with respect to the streaming audio service. Further, such an interface could include media content controls for selecting media items provided by the streaming audio service for play back. 
     The above discussions relating to playback devices, controller devices, playback zone configurations, media content sources, and cloud computing provide only some examples of operating environments within which functions and methods described below may be implemented. Other operating environments and configurations of media playback systems, playback devices, and network devices not explicitly described herein may also be applicable and suitable for implementation of the functions and methods. 
     III. Example Social Queue for a Group of Media Playback Systems 
     As discussed above, embodiments described herein may involve a “social” queue for use by two or more media playback systems that are grouped together. For instance, two or more media playback systems may form a group of media playback systems. Then, the two or more grouped media playback systems may interact with a social queue. 
     Example entities that may carry out one or more of the functions described herein include, without limitation, a playback device (e.g., playback device  200 ), a control device (e.g., control device  300 ), or any suitable computing device (e.g., computing device  500 ). Accordingly, while in describing various functions, reference is made to a media playback system performing those various functions, it will be understood that each of these functions could be performed by any suitable component of a media playback system or by any suitable computing device that is connected to the media playback system. 
     a. Example Group of Media Playback Systems 
     In one example, a first media playback system may form a group with one or more other media playback systems, including at least a second media playback system. As members of the group, the first media playback system and the second media playback system may have a defined relationship with one another. For instance, the first media playback system and the second media playback system may have permission to exchange certain information with one another, or otherwise communicate. Further, the defined relationship may involve the first media playback system and the second media playback system acting accordingly to certain group rules. 
       FIG. 7  is an example environment in which example embodiments may be implemented.  FIG. 7  represents an office environment  700  having offices  710 ,  720 , and  730 , a reception area  740  and a conference room  750 . Office  710  has therein a first media playback system that includes playback devices  712  and  714  and control devices  716  and  718 . Office  730  has a second media playback system that includes playback devices  732  and  736  and control device  736 . 
     The first media playback system and the second media playback system may belong to a first user that is assigned to office  710  and a second user that is assigned to office  730 , respectively. From time to time, such as while working in their respective assigned offices, the first and second users may play back media items, such as audio tracks, on the first media playback system and the second media playback system, respectively. Further, the first and second users may have a variety of social and/or professional relationships. For instance, they may be co-workers, and they may also share similar tastes in music. Because of this shared taste in music, the first and second users may desire to share or mutually engage in a common listening experience. Accordingly, the first and second users may desire to group the first media playback system and the second media playback system to share a social queue. While the first and second user are described by way of example to aid in comprehension of the present invention, the first user, second user, and the relationships between them are not aspects of the present invention. 
     The first media playback system may initiate group formation with the second media playback system. For instance, the first media playback system may send to the second media playback system a first message that invites the second media playback system to group with the first media playback system. The second media playback system may then accept the invitation to form a group in a second message to the first media playback system. Or, the second media playback system may reject the invitation by not sending a second message or by indicating that the invitation is rejected in the second message. 
     Alternatively, the first media playback system may send to the second media playback system a first message that instructs the second media playback system to group with the first media playback system. In some cases, the second media playback system may have prior authorization to form a group in response to receiving a message that instructs or invites group formation. For example, the second media playback system may receive user input indicating authorization to form groups. The authorization may be limited to certain designated media playback systems. 
     The first media playback system and the second media playback system may exchange messages over a network using respective network interfaces, such as network interface  214  of playback device  200  or network interface  306  of control device  300 . The network may be a local area network or a wide area network. In office environment  700 , the network may be a local area network. However, the first media playback system and the second media playback system could also be located in different houses that are connected using a wide area network (e.g., the Internet). 
     The first media playback system and the second media playback system may exchange messages via a computing device, such as computing device  500  of  FIG. 5 . In some examples, the computing device may be one of multiple computing devices that provide a cloud service, such as first-party service  602  of  FIG. 6 . The computing device may connect to the first media playback system and the second media playback via respective connections over a wide area network, such as the Internet. For instance, media playback system  610  and  620  may connect to a computing device that provides a cloud service of cloud  600  using a network of cloud  600 . 
     To facilitate message exchange between the first media playback system and the second media playback system, the computing device may maintain or have access to data indicating the configurations of the media playback systems. For each media playback system, the configuration data may include network addressing information, such as the IP address(es) of the media playback system. The configuration data may also include user information, such as the user profiles of one or more users that have registered with the media playback system. Further, the configuration data may include information indicating groups that the media playback system has joined. 
     To aid in forming the group of media playback systems, the first media playback system may also maintain or have access to data indicating media playbacks systems that are available to group with the first media playback system. Before forming a group, such as during a setup procedure, a media playback system may receive user registration information. The user registration information may include information that identifies one or more users of the first media playback system (e.g., a name and an email address). For instance, the first user and the second user may provide user registration information to the first media playback system and the second media playback system, respectively. 
     Based on such information, the second media playback device may indicate availability to group. For instance, the second media playback system may receive user input that indicates an email address (e.g., the email address of the first user) and willingness to group with a media playback system with which that email address is registered (e.g., the first media playback system). Based on that received user input, the second media playback system may send to the first media playback system an indication that the second media playback system is available to group. 
     In some cases, the first media playback system may receive such availability data over a network from a computing device, such as computing device  500  of  FIG. 5 . Further, in some examples, the computing device may have access to the user registration information for multiple users of media playback systems. The computing device may receive a message from the second media playback system that indicates willingness to group with a particular user (i.e., a particular user having certain registered user information). The computing device may then use look-up the particular user to determine the media playback system with which the particular user is registered. After identifying the media playback system registered to the particular user (e.g., the first media playback system), the computing device may send a message to the first media playback system that indicates that the second media playback system is available to group with the first media playback system. 
     In some cases, a social networking service (e.g., social network service  606  of  FIG. 6 ) may facilitate “discovery” of media playback systems that are available to group with the first media playback system. As noted above, social network services are often characterized at least in part by links between users of the service, such as “friends”, “connections”, “followers”, or “favorites,” among other examples. The second user of the second media playback system may subscribe to a social networking service in which two subscribers that have formed a link within the social networking service are known as “friends.” Through use of the social networking service, the second user of the second media playback system may form “friend” links with one or more other subscribers to the social networking service. Some social networking service provide application programming interfaces (APIs) or other means to access information that subscribers to the social networking service have opted to share with third-parties. For instance, an API may provide access to data indicating the friends of a given subscriber to a social networking service. 
     Among the user&#39;s “friends” in the social networking service, the user of the second media playback service may designate a given friend (e.g., the first user) with whom the user of the second media playback system is willing to group media playback systems. A computing device, such as controller device  300  of  FIG. 3 , or computing device  500  of  FIG. 5 , may receive an indication of such user input designating the friend. The computing device may then access data that correlates subscribers to the social networking service to media playback system with which they have registered. The computing device may look-up the friend within the data to determine which media playback system, if any, that the friend is registered with. The computing device may determine that the friend is registered with the first media playback system and then send to the first media playback system a message indicating availability to group. 
     Before forming the group, the first media playback system may display an indication of media playback systems that are available to group. For instance, a control device of the first media playback system may display on a user interface a list of media playback systems available to group. The first media playback system may then receive user input selecting one or more of the available media playback systems (e.g., the second media playback system). In response, the first media playback systems may send messages to the selected media playback systems inviting group formation. 
       FIG. 11A  is an example user interface  1100 A of a control device, such as control device  718  of  FIG. 7 , that may be configured to facilitate grouping of media playback systems. The user interface  1100 A includes an information region  1102 A, a group selection region  1104 A, a media playback system selection region  1106 A, and a control region  1108 A. The user interface  1100 A as shown is just one example of a user interface that may be provided on a control device and accessed by users to control a media playback system such as the media playback system  100 . Other user interfaces of varying formats, styles, and interactive sequences may alternatively be implemented on one or more control devices to provide comparable control access to a media playback system. 
     The information region  1102 A may include an indication that the user interface is presently configured for group modification. Further the information region  1102 A may include an indication of a number of presently configured groups on the control device (e.g., four groups). The information region  1102 A may include other information as well. 
     The group selection region  1104 A may include selectable (e.g., by way of touch or by using a cursor) icons to select different groups for creation or modification. The group selection region  1104 A may distinguish between groups using labels or other identifiers. For example, a given selectable icon may comprise a group label. The group selection region  1104 A may distinguish between a currently selected group and other groups configured on the control device. For instance, the label of the currently selected group may appear in bold text, among many other examples. In  FIG. 11A , Group  1  is shown as currently selected. 
     The media playback system selection region  1106 A may include indications of media playback systems that are available to group. In  FIG. 1106 , media playback systems  1 ,  2 ,  3 , and  4  are indicted as available to group. The media playback systems may be indicated by reference to a user registered to the media playback system (e.g., Jacob, Mason, Ethan, or Mateo, as shown). In addition, the media playback system selection region  1106 A may indicate the media playback systems in the currently selected group. The media playback system selection region  1106 A may indicate the media playback systems currently in a group may further include selectable icons to select different media playback systems with which to form a group. In  FIG. 11A , Media Playback System  1  is shown as currently selected for inclusion in Group  1 . 
     The control region  1108 A may include selectable icons to control the group configuration. For instance, the control region may include a “Save” icon to commit changes made in the media playback system selection region  1106 A. In some cases, user input selecting such an icon may cause the control device to send a message to the second media playback system. 
     User interface  1100 B in  FIG. 11B  is another instance of user interface  1100 A. The user interface  1100 B includes an information region  1102 B, a group selection region  1104 B, a media playback system selection region  1106 B, and a control region  1108 B. In the group selection region  1104 B, Group  2  is shown as currently selected. Further, in the media playback system selection region  1106 B, Media Playback Systems  1 ,  2 , and  3  are shown as currently selected for inclusion in Group  2 . 
     Within examples, the first media playback system may have access to data indicating a “friend” list of the first media playback system. The friend list may indicate, as “friends,” media playback systems that have indicated availability to group to the first media playback system, such as via a social networking service. In some examples, the media playback systems indicated in the friends list may have given prior authorization to group. A device, such as the control device  300  of  FIG. 3  or the computing device  500  of  FIG. 5 , may maintain such a “friend” list for the first media playback system. The friend list may facilitate group formation. For instance, a control device of the first media playback system may display on a user interface an indication of the friend list. The first media playback system may then receive user input selecting a “friend” (e.g., the second media playback system) and subsequently form a group with the friend. Then, the first media playback system may receive user input selecting a second “friend” (e.g., a third media playback system) and then form a group that includes the first, second, and third media playback systems. Alternatively, at some point thereafter, the first media playback system may leave the group with the second media playback system and form a group with the third media playback system. Other groups are certainly possible as well. 
     After forming the group, the first media playback system may display an indication of the group. For instance, a control device of the first media playback system may display on a user interface the indication of the group. The indication of the group may depict the group in a variety of ways. For instance, the indication may be a group name. Alternatively, the group may be indicated by reference to one or more users that are registered with each media playback system in the group. 
     The first message and the second message may be responsive to user input received by the first media playback system and the second media playback system, respectively. For instance, the first media playback system may receive user input that instructs the first media playback system to invite the second media playback system to form a group. After receiving the first message, the second media playback system may display an indication of the invitation from the first media playback system. The second media playback system may then receive user input indicating acceptance or rejection of the invitation to form the group, and then, in the second message, respond to the user input accordingly. 
     As noted above, media playback systems in a group may adhere to certain group rules. The group rules may facilitate compatibility with certain features. For instance, an example group rule may suggest that all media playback systems within the group have access to a particular audio source, such as a particular streaming audio service. This rule may support features that may necessitate the media playback systems in the group having access to media items provided by the streaming audio service. For instance, all of the members of a group may attempt to play back an audio track from the streaming audio service. 
     In some cases, during group formation, a determination may be made whether the media playback systems in the group adhere to the group rules. In one embodiment, the first media playback system may make such a determination. For instance, in a first message that invites a second media playback system to form a group, the first media playback may ask for a response from the second media playback system that indicates adherence by the second media playback system with one or more group rules. The second media playback system may then include such a response in a second message (which may also indicate acceptance of the invitation to form the group). After receiving the second message, the first media playback system may determine whether the second media playback system adheres to the group rules based on the response in the second message. 
     Alternatively, the second media playback system may make available configuration data to media playback systems with which it has indicated availability to form a group. The configuration data may indicate parameters on which group rules may be based. For example, the configuration data may indicate that the second media playback system has access to a particular streaming audio service. Then, based on such configuration data, the first media playback system may determine whether the second media playback system adheres to the group rules. 
     In other cases, a computing system, such as the computing system  500  of  FIG. 5 , may determine whether the second media playback system adheres to the group rules. As noted above, in some cases, the first media playback system and the second media playback system may exchange messages involved in group formation via a computing device. This computing device (or a similar computing device connected to that computing device via a network) may maintain or have access to the configuration data of the second media playback system noted above. Based on this configuration data, the computing device may determine whether the second media playback system adheres to the group rules. After determining that the second media playback system adheres to the group rules, the computing system may send a message to the first media playback system that indicates that the first media playback system adheres to the group rules. After receiving such a message, the first media playback system may then form a group with the second media playback system. 
     b. Example Method for Generating a Social Queue 
     As noted above, two or more media playback systems in a group may share access to a social queue. Media playback systems within the group may interact with the social queue in various ways. For instance, a given media playback system within the group may create a social queue, modify the social queue, or playback media items within the social queue. 
     Method  800  shown in  FIG. 8  presents an embodiment of a method that can be implemented within an operating environment involving, for example, the media playback system  100  of  FIG. 1 , one or more of the playback device  200  of  FIG. 2 , and one or more of the control device  300  of  FIG. 3 . Method  800  may include one or more operations, functions, or actions as illustrated by one or more of blocks  802 - 806 . Although the blocks are illustrated in sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.
         i. Receiving (1) a First Message Indicating a First Set of Media Items, and (2) A Second Message Indicating a Second Set of Media Items.       

     At block  802 , the method involves receiving a first message indicating a first set of media items and a second message indicating a second set of media items. For instance, computing device  500  may receive the first message and the second message via network interface  506 . Computing device  500  may provide a cloud service that facilitates carrying out the present method to generate a social queue. For instance, first-party service  602  of cloud  600  may include a computing device  500  that receives the first message and the second message. Alternatively, a component of media playback system may receive the first message and the second message via a network interface, such as network interface  214  of playback device  200  or network interface  306  of control device  300 . 
     Computing device  500  may receive the first message from a first media playback system and the second message from a second media playback system. Within examples, computing device  500  may receive the first message from a controller device or a playback device. For instance, network interface  506  may connect over a network (e.g., the Internet) with respective network interfaces of devices of the first media playback system and the second media playback system. In one example, referring back to  FIG. 7 , computing device  500  may receive the first message and the second message from the first media playback system in office  710  and the second media playback system in office  730 , respectively. 
     Alternatively, computing device  500  may receive the first message from a computing device associated with the first media playback system. For instance, the computing device  500  may receive the first message from the first user&#39;s smartphone or personal computer. The association may be a particular link between the computing device and the first media playback system that establishes that messages from the computing device may specify a first set of media items on behalf of the first media playback system. For instance, the computing device may have a memory with instructions stored thereon such that the computing device may be a control device of the first media playback system. While the computing device need not necessarily control the first media playback system at all times, the computing device, by reason of linking with the first media playback system as a control device of the first media playback system, may specify the first set of media items. 
     In some cases, before sending the first message and the second message, the first media playback system and the second media playback system may form a group or indicate availability to form a group with one another. For example, before receiving the first message and the second message, the computing device  500  may receive a third message indicating that the first media playback system and the second media playback system shall form a group of media playback systems. After receiving the third message, the computing device  500  may cause the first media playback system and the second media playback system to form the group of media playback systems. Within examples, the first media playback system, the second media playback system, and or a third party service (e.g., social networking service  606  of  FIG. 6 ) may send the third message. For instance, the first media playback system may send a message inviting the second media playback system to group. Alternatively, the third party service may send a message indicating two media playback systems to group. 
     The first set of media items may take a variety of different forms. The media items may include, for example, any of the example audio content noted above. The first set of media items may be media items that are currently queued for playback on the first media playback system. As noted above, playback queue region  440  of controller interface  400  shown in  FIG. 4  may include graphical representations of audio items in a queue of a media playback system. In other cases, the first set of media items may be media items in a queue that has been saved for later playback on the first media playback system. Yet, in other cases, the first set of items may be a playlist. In still other cases, the first set of media playback items may include any media items designated for inclusion in the social queue. For instance, the first media playback system may receive user input via a controller interface, such as controller interface  400  of  FIG. 4 . The user input may designate certain media items for inclusion in the social queue. The second set of media items may, for example, represent any of the above examples with respect to the second media playback system. Other examples are certainly possible as well. 
     As noted above, the first user (of the first media playback system) and the second user (of the second media playback system) may share certain music interests, such as hip-hop. The first user and the second user may desire to enjoy their mutual interest in hip-hop by sharing media items via a social queue. In one example, the first user may designate on a controller interface of control device  718  a playlist some of her favorite hip-hop tracks. The first media playback system may then send an indication of these designated hip-hop tracks as a first set of media items in a first message to computing device  500 . The second user may then designate on a controller interface of control device  736  tracks from a new hip-hop album. The first media playback system may then send an indication of these designated tracks from the new hip-hop album as a second set of media items in a second message to computing device  500 .
         ii. Generating a Playback Queue       

     At block  804 , the method involves generating a playback queue comprising the first set of media items indicated in the first message and the second set of media items indicated in the second message. In particular, the generated playback queue may be a “social queue” that includes media items received from both the first media playback system and the second media playback system. 
     The computing device may generate the playback queue with the first set of media items and the second set of media items in different orders. For instance, the generated playback queue may list media items in the order that they are received by the computing device  500 . Alternatively, the generated playback queue may list media items in random order. 
     In some cases, the first media playback system may have access to different audio content sources than the first media playback system. For instance, the first media playback system may have access to a first steaming audio service which provides 20 million streaming audio tracks. The second media playback system may have access to a second streaming audio service which provides access to 15 million streaming audio tracks. Typically, access is gained to a streaming audio service by registering with the audio service (i.e., providing user information to the audio service to create a user profile). Some audio services may also require payment of a subscription fee before accessing the streaming audio service. The first streaming audio service may provide many of the same audio tracks as the second streaming audio service, but, in some cases, the first streaming audio service may provide some audio tracks that are not available with the second streaming audio service. Similarly, the second streaming audio service may provide some audio tracks that are not available with the first streaming audio service. 
     In one instance, the first set of media items may include one or more audio tracks from the first audio service. For instance, a given media item in the first set of media items may have a particular media item identifier to access the one or more audio tracks using the first streaming service. The first message may specify the media item identifier for each media item in the first set. A media item identifier may be a string or a number that distinguishes the audio track. In some cases, the media item identifier may a URI or URL. 
     Since, as noted above, the second media playback system has access to the first streaming media service and not the second streaming media service, the second media playback system may be unable to playback the one or more audio tracks using the first audio service. However, the second media playback system may have access to the one or more audio tracks via the second streaming audio service. Therefore, the computing device  500  may cross-link the media item identifier of the first streaming service to a media item identifier of the second streaming audio service. For a given media item, cross-linking may involve searching the second media service provider for the media item and then determining the media item identifier of the media item in the second streaming audio service. To find the media item, the computing device may search the second audio service by title, artist, album, or by any suitable identifying information. To facilitate searching, each media item may have metadata embedded in the media item or associated with the media file. The metadata may specify various information about the file, such as the title, the artist, or the album, among other information. After cross-linking the media item between the first streaming audio service and the second streaming audio service, the social queue may include, for a given media item, a media item identifier of the first streaming audio service and a media item identifier of the second streaming audio service. 
     In other cases, before adding a given media playback item to the generated playback queue, the computing device  500  may determine whether the media playback systems in the group have access to the media playback item. For instance, the computing device  500  may determine that the first media playback system has access to the given media item using a given service (e.g., the first streaming media service or the second streaming media service). And the computing device  500  may determine that the second media playback system has access to the given media item using the given service. Then, based at least in part on the determinations, the computing device may add the given media item to the playback queue.
         iii. Transmitting the Generated Playback Queue       

     At block  806 , the method involves transmitting, to at least one of the first media playback system and the second media playback system, the generated playback queue. For instance, computing device  500  may transmit the generated playback queue to the first playback device in office  710  and the second playback device in office  730 . In some cases, the computing device  500  may transmit the generated playback queue after receive a request for the generated playback queue (e.g., a request to play back media items in the generated playback queue). 
     In some cases, before transmitting the generated playback queue, computing device  500  may determine that at least one of the first media playback system and the second media playback system is in the group of media playback systems. The computing device  500  may then transmit the generated playback queue to each media playback system in the group of media playback systems. 
     The social queue (i.e., the generated playback queue) may cause playback of the media items in the social queue in a variety of different ways. In one example, the social queue may cause the first media playback system to playback the media items in the social queue as a radio-type channel in which the first media playback system can playback the media items, but is not necessarily able to control the order of playback. In other examples, the social queue may cause playback of the media items in round-robin order or in random order (i.e., shuffled), such as accordingly to a shuffling algorithm. In yet other examples, the first media playback system may receive user input that selects one or more particular media items from the social queue to playback. Further examples are possible as well. 
     Media playback systems may modify the generated playback queue (i.e., the social queue). For instance, after generating the playback queue, the computing device  500  may, receive, from the first media playback system, a command to modify the playback queue. The received command may indicate one or more media items. The command may instruct the computing device  500  to add the one or more media items indicated by the received command to the generated playback queue. Or the command may instruct the computing device  500  to remove the one or more media items indicated by the received command from the generated playback queue. Alternatively, the command may instruct the computing device  500  order or re-order the one or more media items indicated by the received command within the generated playback queue. After modifying the social queue, the computing device  500  may transmit, to the first media playback system and/or the second media playback system, the modified playback queue. This transmission may update the social queue to reflect the modification. 
     In some cases, the computing device  500  may carry out the received command to modify the playback queue, but, in other cases, the computing device  500  may decline to carry out the received command. Before carrying out the received command, the computing device  500  may determine that the received command obeys one or more group rules or queue rules. Group rules may apply to any social queue created by the group while queue rules may apply to a particular queue. Such group rules or queue rules may facilitate social aspects of the social queue. For instance, one rule may suggest that a command may not add or remove more than ten media items from the social queue per hour. This rule may facilitate more equal control of the social queue (e.g., adding and removing media items) by the first user and the second user. Another rule may suggest that the computing device send a message indicating the modification to the social queue to the first media playback system and the second media playback system. 
     A given group of media playback systems may have multiple social queues. Media playback systems within the group may select among the social queues. For instance, one social queue may be labeled “Opera.” Users of media playback systems may tend to designate tracks in the opera genre in the “Opera” social queue. In some cases, the “Opera” social queue may have a queue rule that requires media items in the “Opera” queue to be audio tracks in the opera genre. For instance, before adding an item to the generated queue, the computing system may determine that the media item is in the opera genre. In some case, the computing system may base such a determination upon the media item&#39;s metadata, which may specify the genre of the media item, among other information. Other social queues may be labeled for other genres. Other social queues may be based on artist, album, date, or any other conceivable rationale for grouping. In some cases, the media items may have no apparent relationship to one another. 
       FIG. 12A  is an example user interface  1200 A of a control device, such as control device  718  of  FIG. 7 , that may be configured to facilitate various interactions with a social queue, such as playback or modification. The user interface  1200 A includes an information region  1202 A, a queue selection region  1204 A, a social queue region  1206 A, and a control region  1208 A. The user interface  1200 A as shown is just one example of a user interface that may be provided on a control device accessed by users to control a media playback system such as the media playback system  100 . Other user interfaces of varying formats, styles, and interactive sequences may alternatively be implemented on one or more control devices to provide comparable control access to a media playback system. 
     The information region  1202 A may include an indication of a currently selected group. In  FIG. 12A , Group  1  is shown as currently selected. Further the information region  1202 A may include an indication of a number of presently configured social queues (e.g., three social queues). The information region  1202 A may include other information as well. 
     The queue selection region  1204 A may include selectable (e.g., by way of touch or by using a cursor) icons to select different queues for playback, creation, or modification. The queue selection region  1204 A may distinguish between groups using labels or other identifiers. For example, a given selectable icon may comprise a queue label. The queue selection region  1204 A may distinguish between a currently selected queue and other queues configured on the control device. For instance, the label of the currently selected queue may appear in bold text, among many other examples. In  FIG. 12A , Queue  1  is shown as currently selected. 
     The social queue region  1206 A may include indications (e.g., graphical representations) of media items that are in the currently selected social queue. The graphical representations of media items in the social queue region  1206 A may include track titles, artist names, track lengths, and other relevant information associated with the media items in the social queue. In one example, graphical representations of media items may be selectable to bring up additional selectable icons to manage and/or manipulate the social queue and/or media items represented in the social queue. For instance, a represented media item may be removed from the playback queue, moved to a different position within the playback queue, or selected to be played immediately, or after any currently playing audio content, among other possibilities. 
     The control region  1208 A may include selectable icons to control the social queue configuration. For instance, the control region may include a “Save” icon to commit changes made in the social queue region  1206 A. In some cases, user input selecting such an icon may cause the control device to send a message to a media playback system. 
     User interface  1200 B in  FIG. 12B  is another instance of user interface  1200 A. The user interface  1200 B includes an information region  1202 B, a queue selection region  1204 B, a social queue region  1206 B, and a control region  1208 B. In the queue selection region  1104 B, Queue  2  is shown as currently selected. 
     A media playback system may join multiple groups each having multiple social queues. In aggregate, from the perspective of the user, each queue may represent different “buckets” of media items. One bucket may be the “Opera” social queue noted above. Another bucket may represent a social queue belonging to a group that includes media playback systems registered to the user&#39;s friends in a particular social network. A third bucket may represent another social queue belonging to a group that includes media playback systems registered to a subset of a user&#39;s friends in another social network (e.g., friends from college). Many combinations are possible. 
     In some cases, a generated queue may include a set of media items from a source that is not the first media playback system or the second media playback system. For instance, computing device  500  may receive an additional set of media items from a third media playback system. In some cases, the third media playback system may add the additional set of media items to the generated playback queue. In other cases, the third media playback system may generate a second playback queue that comprises at least the additional set of media items. Then, the third media playback system may update the social queue and/or provide the second queue to the group. For example, the third media playback system may transmit the generated second playback queue to the first media playback system and/or the second media playback system. 
     Alternatively, computing device  500  may receive an additional set of media items from a computing device, such as another instance of computing device  500 . The second instance of computing device  500  may provide a cloud service, such as a file hosting service or a social networking service, among other examples. For example, as part of a social networking service, the second instance of computing device  500  may provide various features. As one example, the social network service may provide an interface for displaying the social queue. The media playback system may have previously registered with the social networking service, such that the media playback system and the social networking service share certain information. For instance, registration may involve registering a user account associated with a media playback system with a user profile of the social networking service. The social networking service may then recognize the user profile as being associated with a certain media playback system. Further, the social networking system may recognize “friend” connections of the user profile. The social networking system may also recognize groups formed by the certain media playback system with media playback systems registered to other user profiles of the social networking service. Further, the social networking service may provide an interface that indicates such user profiles, media playback systems, and the groups to which the user profiles belong. As noted above, such an interface may be provided via a web browser or via a specialized application for the cloud service, among other examples. 
     The interface may also display an indication of the social queue, or the media items in the social queue. The indication of the social queue may indicate the media items in the social queue in various ways. For example, the interface may display an indication of which media items in the social queue were selected via the social networking service. The interface may display an indication of which user of the social networking service added particular media items to the social queue. Many examples are possible. 
     The interface may also display controls for selecting the additional set of media items from audio content sources available to media playback system registered to the user. In some cases the interface may display controls for selecting media tracks to include in a social queue for use by a group. An indication of selected media items may appear on the interface provided by the social network. Further, the social networking service may update its interface to indicate the selected media items in the social queue. Also, many social networking services also have messaging systems. An example social networking service may send, via a message system, messages that indicate that a particular social queue has been updated with an additional set of media items. Recipients of such a message may include users who have grouped their media playback systems together to use the particular social queue. 
     Those having skill in the art will appreciate that numerous other arrangements are possible in addition to the examples provided above. For example, a device of a media playback system, such a control device, or a playback device, may carry out one or more of the functions described above alone or in combination with another device. 
     c. Example Method to Facilitate a Social Queue of a Group of Media Playback Systems 
     In one example, a control device of a media playback system may facilitate grouping media playback systems into a group having a social queue. However, one having skill in the art will appreciate that any suitable computing device may facilitate such features. 
     Method  900  shown in  FIG. 9  presents an embodiment of a method that can be implemented within an operating environment involving, for example, the media playback system  100  of  FIG. 1 , one or more of the playback device  200  of  FIG. 2 , one or more of the control device  300  of  FIG. 3 , and one or more of computing device  500  of  FIG. 5 . Method  900  may include one or more operations, functions, or actions as illustrated by one or more of blocks  902 - 906 . Although the blocks are illustrated in sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.
         i. Receiving a Command to Form a Group of Media Playback Systems.       

     At block  902 , the method involves receiving, at a computing device associated with a first media playback system, a command to form a group of media playback systems that comprises the first media playback system and at least one other media playback system. The computing device associated with a first media playback device may be a control device, such as control device  300 . Alternatively, the computing device may be any computing device having a processor, memory, and a network interface. 
     As noted above, in  FIG. 7 , a first media playback system in office  710  includes control devices  716  and  718  (as well as playback devices  712  and  714 ). Also, control devices  716  and  718  may be instances of control device  300  of  FIG. 3 . In one example, control device  716  may receive via a controller interface (e.g., controller interface  1100 A or  1100 B) user input that indicates a command to form a group of media playback systems. The command may indicate the second media system in office  730 , which includes playback devices  732  and  734 , and also control device  736 . The command may also indicate one or more media playback systems in addition to the second media playback system. 
     In some cases, before receiving the command to form the group of media playback systems, control device  716  may display a list of media playback systems available for grouping. Control device may display such a list on a user interface, such as user interface  1100 A or  1100 B. As noted above, to aid in forming the group of media playback systems, the first media playback system may maintain or have access to data indicating media playbacks systems that are available to group with the first media playback system. Control device  716  may access such data from a memory, such as memory  304 , or request and then receive such data over a network interface, such as network interface  306 . After displaying the list of available media playback systems, control device  716  may receive user input indicating a selection of one or more of the media playback systems displayed in the list of media playback systems available for grouping. In one example, control device  716  may receive user input representing a selection of the second media playback system in office  730 .
         ii. Receiving an Identification of at Least One Source of Audio for Playback by the Group of Media Playback Systems.       

     At block  904 , the method involves receiving, at the computing device, an identification of at least one source of audio for playback by the group of media playback systems. For instance, control device  300  may receive an identification of at least one source of audio for playback by the group of media playback systems. 
     Referring back to  FIG. 7 , in one example, control device  716  may receive via a controller interface user input that indicates an identification of at least one source of audio for playback by the group of media playback systems. Before receiving the identification, control device  716  may display available sources of audio. For example, control device  716  may display available sources of audio in an audio content sources region  450  of a controller interface  400 . Control device  716  may then receive user input indicating a selection of at least one source of audio. 
     Available sources of audio may include, without limitation, a queue of the first media playback system, an auxiliary input (i.e., line-in) input, an internet radio channel, a playlist of locally available media items, or a playlist of media items available from a streaming media service. The queue of the first media playback system may be a queue of media items currently queued for playback, or it may be a saved queue of media playback items. Other examples of audio sources are possible as well. 
     In some cases, the at least one source of audio for playback may include at least a first audio source and a second audio source. In such an instance, the control device  716  may send an instruction to the second media playback system to select the second audio source. The control device may then receive user input that indicates a selection of the first audio source. And the control device  716  may receive a message from the second media playback system that indicates a second audio source.
         iii. Sending a Message Comprising (i) an Indication of the Received Command to Form the Group of Media Playback Systems and (ii) an Indication of the at Least One Source of Audio for Playback by the Group of Media Playback Systems.       

     At block  906 , the method involves sending, by the computing device to the at least one other media playback system, a message comprising (i) an indication of the received command to form the group of media playback systems and (ii) an indication of the at least one source of audio for playback by the group of media playback systems. 
     The message comprising the indication of the received command to form the group of media playback systems may cause the media playback system(s) receiving the message to form a group with the first media playback system. In one example, control device  716  may send message(s) inviting the at least one other media playback system to group. Control device  300  may then receive message(s) from the at least one other media playback system that acknowledges the indication of the command to form the group of media playback systems. Such acknowledgement may indicate to the control device  300  willingness to form the group. In some cases, control device  716  may cause the first media playback to form the group in response to the indication of the command to form the group. In other case, control device  716  may form the group in response to receiving the acknowledgement. The first media playback system and the second media playback system may then form a group. 
     The indication of the at least one source of audio for playback by the group of media playback systems may be a social queue, or it may list media items to include in a social queue, among other examples. After receiving the indication, a media playback system may play back the at least one source of audio, or otherwise interact with it. 
     In some cases, the first media playback system and the second media playback system may have access to the same media items via different audio sources. For example, the first media playback system may have access to a first media service provider and the second media player may have access to a second media service provider. In such a circumstance, the control device may cross-link the media items between the two different audio sources. The indication of the at least one source of audio for playback may include a media item identifier for each audio source. Then, the first media playback system and the second media playback system may play back the same media items from a first audio source and a second audio source, respectively. 
     In one example, the first audio source and the second audio source may be a playback queue of the first media playback system and a playback queue of the second media playback system respectively. The playback queue of the first media playback system may indicate a first set of media items. A given media item of the playback queue of the first media playback system may be associated with a respective media item identifier of the first media service provider (e.g., a first streaming audio service). At the same time, the playback queue of second first media playback system may indicate a second set of media items. A given media item of the playback queue of the second media playback system may be associated with a respective media item identifier of the second media service provider (e.g., a second streaming audio service). 
     Given these two audio sources, control device  716  may associate the respective media item identifier of the first media service provider with a respective media item identifier of the second media service provider. Control device  716  may then send to the second media playback system an indication of the playback queue of the first media playback system. The indication may include at least the respective media item identifier of the second media service provider. After receiving the indication, the second media playback system may play back the media items in the playback queue of the first media playback system by accessing the media items at the second media service provider using the respective media item identifiers of the media items at the second media service provider. 
     d. Second Example Method to Facilitate a Social Queue of a Group of Media Playback Systems 
     In another example, a computing device providing a cloud service, such as a social networking service, may facilitate grouping media playback systems into a group having a social queue. However, one having skill in the art will appreciate that any suitable computing device may facilitate such features. 
     Method  1000  shown in  FIG. 10  presents an embodiment of a method that can be implemented within an operating environment involving, for example, the media playback system  100  of  FIG. 1 , one or more of the playback device  200  of  FIG. 2 , one or more of the control device  300  of  FIG. 3 , and one or more of computing device  500  of  FIG. 5 . Method  900  may include one or more operations, functions, or actions as illustrated by one or more of blocks  902 - 906 . Although the blocks are illustrated in sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.
         i. Receiving an Instruction that Causes at Least a First Media Playback System and a Second Media Playback System to Form a Group of Media Playback Systems.       

     At block  1002 , the method involves receiving an instruction that causes at least a first media playback system and a second media playback system to form a group of media playback systems. A computing device, such as computing device  500  of  FIG. 5  may receive the instruction over a network interface, such as network interface  506 . 
     In some cases, a first computing device may receive the instruction that causes group formation from a second computing device involved in providing a cloud service. For instance, the second computing device may host a webpage that provides a user interface for selecting media playback systems to group. Alternatively, the second computing device may provide a “back-end” to a “front-end” that provides a user interface for selecting media playback systems to group. The “front-end” may be an application on a mobile device or a web site, among other examples. The “back-end” may receive indications of user input on the front-end that selects media playback systems to group. The “back-end” may then send the instruction that causes group formation to a first computing device. 
     In other cases, the first computing device may receive the instruction that causes group formation from a control device of a media playback system (e.g., the first media playback system). The control device may receive user input selecting one or more media playback systems to group (including, for example, the second media playback system). The control device may then sent the instruction to group to the first computing device.
         ii. Receiving a First Message Indicating a First Set of Media Items and a Second Message Indicating a Second Set of Media Items.       

     At block  1004 , the method involves receiving, from a third-party service provider, a first message indicating a first set of media items and a second message indicating a second set of media items. For instance, computing device  500  may receive the first message and the second message via network interface  506 . 
     Computing device  500  may receive the first message from a first media playback system and the second message from a second media playback system. Within examples, computing device  500  may receive the first message from a controller device or a playback device. For instance, network interface  506  may connect over a network (e.g., the Internet) with respective network interfaces of devices of the first media playback system and the second media playback system. In one example, referring back to  FIG. 7 , computing device  500  may receive the first message and the second message from the first media playback system in office  710  and the second media playback system in office  730 , respectively. 
     Alternatively, computing device  500  may receive the first message from a computing device associated with the first media playback system. For instance, the computing device  500  may receive the first message from the first user&#39;s smartphone or personal computer. The association may be a particular link between the computing device and the first media playback system that establishes that messages from the computing device may specify a first set of media items on behalf of the first media playback system. For instance, the computing device may have a memory with instructions stored thereon such that the computing device may be a control device of the first media playback system. 
     The first set of media items may take a variety of different forms. The media items may include, for example, any of the example audio content noted above. The first set of media items may be media items that are currently queued for playback on the first media playback system. As noted above, playback queue region  440  of controller interface  400  shown in  FIG. 4  may include graphical representations of audio items in a queue of a media playback system. In other cases, the first set of media items may be media items in a queue that has been saved for later playback on the first media playback system. Yet, in other cases, the first set of items may be a playlist. In still other cases, the first set of media playback items may include any media items designated for inclusion in the social queue. For instance, the first media playback system may receive user input via a controller interface, such as controller interface  400  of  FIG. 4 . The user input may designate certain media items for inclusion in the social queue. The second set of media items may, for example, represent any of the above examples with respect to the second media playback system. Other examples are certainly possible as well.
         iii. Generating a Playback Queue.       

     At block  1006 , the method involves generating a playback queue comprising the first set of media items indicated in the received first message and the second set of media items indicated in the received second message. In particular, the generated playback queue may be a “social queue” that includes media items received from both the first media playback system and the second media playback system.
         iv. Transmitting the Generated Playback Queue.       

     At block  1008 , the method involves transmitting, to each media playback system in the group of media playback system, the generated playback queue. For instance, computing device  500  may transmit the generated playback queue to the first playback device in office  710  and the second playback device in office  730 . In some cases, the computing device  500  may transmit the generated playback queue after receive a request for the generated playback queue (e.g., a request to playback media items in the generated playback queue). 
     In some cases, before transmitting the generated playback queue, computing device  500  may determine that at least one of the first media playback system and the second media playback system is in the group of media playback systems. The computing device  500  may then transmit the generated playback queue to each media playback system in the group of media playback systems. 
     In addition, for the methods  800 ,  900 , and  1000  and other processes and methods disclosed herein, the flowcharts shows functionality and operation of one possible implementation of present embodiments. In this regard, each block may represent a module, a segment, or a portion of program code, which includes one or more instructions executable by a processor for implementing specific logical functions or steps in the process. The program code may be stored on any type of computer readable medium, for example, such as a storage device including a disk or hard drive. The computer readable medium may include non-transitory computer readable medium, for example, such as computer-readable media that stores data for short periods of time like register memory, processor cache and Random Access Memory (RAM). The computer readable medium may also include non-transitory media, such as secondary or persistent long term storage, like read only memory (ROM), optical or magnetic disks, compact-disc read only memory (CD-ROM), for example. The computer readable media may also be any other volatile or non-volatile storage systems. The computer readable medium may be considered a computer readable storage medium, for example, or a tangible storage device. In addition, for the method  500  and other processes and methods disclosed herein, each block in  FIG. 5  may represent circuitry that is wired to perform the specific logical functions in the process. 
     IV. Conclusion 
     The description above discloses, among other things, various example systems, methods, apparatus, and articles of manufacture including, among other components, firmware and/or software executed on hardware. It is understood that such examples are merely illustrative and should not be considered as limiting. For example, it is contemplated that any or all of the firmware, hardware, and/or software aspects or components can be embodied exclusively in hardware, exclusively in software, exclusively in firmware, or in any combination of hardware, software, and/or firmware. Accordingly, the examples provided are not the only way(s) to implement such systems, methods, apparatus, and/or articles of manufacture. 
     As indicated above, the present application involves a social queue for a group of media playback systems. In one aspect, a method is provided. The method involves receiving, from a first media playback system, a first message indicating a first set of media items and receiving, from a second media playback system, a second message indicating a second set of media items. The method also involves generating a playback queue comprising the first set of media items indicated in the first message and the second set of media items indicated in the second message. The method further involves transmitting, to at least one of the first media playback system and the second media playback system, the generated playback queue. 
     In another aspect, a device is provided. The device includes a processor, a network interface, a non-transitory computer-readable storage medium, and program logic stored on the non-transitory computer-readable medium and executable by the processor to perform functions. The functions include receiving, from a first media playback system, a first message indicating a first set of media items and receiving, from a second media playback system, a second message indicating a second set of media items. The functions also include generating a playback queue comprising the first set of media items indicated in the first message and the second set of media items indicated in the second message. The functions further include transmitting, to at least one of the first media playback system and the second media playback system, the generated playback queue. 
     In yet another aspect, a non-transitory computer readable memory is provided. The non-transitory computer readable memory has stored thereon instructions executable by a computing device to cause the computing device to perform functions. The functions include receiving, from a first media playback system, a first message indicating a first set of media items and receiving, from a second media playback system, a second message indicating a second set of media items. The functions also include generating a playback queue comprising the first set of media items indicated in the first message and the second set of media items indicated in the second message. The functions further include transmitting, to at least one of the first media playback system and the second media playback system, the generated playback queue. 
     In another aspect, a method is provided. The method involves receiving, at a computing device associated with a first media playback system, a command to form a group of media playback systems that comprises the first media playback system and at least one other media playback system. The method also involves receiving, at the computing device, an identification of at least one source of audio for playback by the group of media playback systems. The method further involve sending, by the computing device to the at least one other media playback system, a message comprising (i) an indication of the received command to form the group of media playback systems and (ii) an indication of the at least one source of audio for playback by the group of media playback systems. 
     In yet another aspect, a device is provided. The device includes a processor, a network interface, a non-transitory computer-readable storage medium, and program logic stored on the non-transitory computer-readable medium and executable by the processor to perform functions. The functions include receiving, at a computing device associated with a first media playback system, a command to form a group of media playback systems that comprises the first media playback system and at least one other media playback system. The function also include receiving, at the computing device, an identification of at least one source of audio for playback by the group of media playback systems. The functions further include sending, by the computing device to the at least one other media playback system, a message comprising (i) an indication of the received command to form the group of media playback systems and (ii) an indication of the at least one source of audio for playback by the group of media playback systems. 
     In another aspect, a non-transitory computer readable memory is provided. The non-transitory computer readable memory has stored thereon instructions executable by a computing device to cause the computing device to perform functions. The functions include receiving, at a computing device associated with a first media playback system, a command to form a group of media playback systems that comprises the first media playback system and at least one other media playback system. The function also include receiving, at the computing device, an identification of at least one source of audio for playback by the group of media playback systems. The functions further include sending, by the computing device to the at least one other media playback system, a message comprising (i) an indication of the received command to form the group of media playback systems and (ii) an indication of the at least one source of audio for playback by the group of media playback systems. 
     In yet one aspect, a method is provided. The method involves receiving an instruction that causes at least a first media playback system and a second media playback system to form a group of media playback systems. The method also involves receiving, from a third-party service provider, a first message indicating a first set of media items and a second message indicating a second set of media items. The method further involves generating a playback queue comprising the first set of media items indicated in the received first message and the second set of media items indicated in the received second message. The method also involves transmitting, to each media playback system in the group of media playback system, the generated playback queue. 
     In another aspect, a device is provided. The device includes a processor, a network interface, a non-transitory computer-readable storage medium, and program logic stored on the non-transitory computer-readable medium and executable by the processor to perform functions. The functions include receiving an instruction that causes at least a first media playback system and a second media playback system to form a group of media playback systems. The functions also include receiving, from a third-party service provider, a first message indicating a first set of media items and a second message indicating a second set of media items. The functions further include generating a playback queue comprising the first set of media items indicated in the received first message and the second set of media items indicated in the received second message. The functions also include transmitting, to each media playback system in the group of media playback system, the generated playback queue. 
     In yet another aspect, a non-transitory computer readable memory is provided. The non-transitory computer readable memory has stored thereon instructions executable by a computing device to cause the computing device to perform functions. The functions include receiving an instruction that causes at least a first media playback system and a second media playback system to form a group of media playback systems. The functions also include receiving, from a third-party service provider, a first message indicating a first set of media items and a second message indicating a second set of media items. The functions further include generating a playback queue comprising the first set of media items indicated in the received first message and the second set of media items indicated in the received second message. The functions also include transmitting, to each media playback system in the group of media playback system, the generated playback queue. 
     Additionally, references herein to “embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one example embodiment of an invention. The appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. As such, the embodiments described herein, explicitly and implicitly understood by one skilled in the art, can be combined with other embodiments. 
     The specification is presented largely in terms of illustrative environments, systems, procedures, steps, logic blocks, processing, and other symbolic representations that directly or indirectly resemble the operations of data processing devices coupled to networks. These process descriptions and representations are typically used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. Numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, it is understood to those skilled in the art that certain embodiments of the present disclosure can be practiced without certain, specific details. In other instances, well known methods, procedures, components, and circuitry have not been described in detail to avoid unnecessarily obscuring aspects of the embodiments. Accordingly, the scope of the present disclosure is defined by the appended claims rather than the forgoing description of embodiments. 
     When any of the appended claims are read to cover a purely software and/or firmware implementation, at least one of the elements in at least one example is hereby expressly defined to include a tangible, non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on, storing the software and/or firmware.