Patent Publication Number: US-2023154445-A1

Title: Spatial music creation interface

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to augmented reality devices and interfaces, and to collaborative augmented reality sessions for audio creation. 
     BACKGROUND 
     A head-worn device may be implemented with a transparent or semi-transparent display through which a user of the head-worn device can view the surrounding environment. Such devices enable a user to see through the transparent or semi-transparent display to view the surrounding environment, and to also see objects (e.g., virtual objects such as 3D renderings, images, video, text, and so forth) that are generated for display to appear as a part of, and/or overlaid upon, the surrounding environment. This is typically referred to as “augmented reality.” 
     A head-worn device may additionally completely occlude a user’s visual field and display a virtual environment through which a user may move or be moved. This is typically referred to as “virtual reality.” As used herein, the term “augmented reality” or “AR” refers to both augmented reality and virtual reality as traditionally understood, unless the context indicates otherwise. 
     A user of the head-worn device may access a messaging or social network application to view or share content with other users of the application. In some cases, live or stored content can be viewed and enhanced or modified by the user. That is, images, video or other media for enhancement can be captured from a live camera or can be retrieved from local or remote data storage. 
     As referred to herein, the phrase “augmented reality experience,” includes or refers to various image processing operations corresponding to an image modification, filter, media overlay, transformation, and the like, as described further herein. In some examples, these image processing operations provide an interactive experience of a real-world environment, where objects, surfaces, backgrounds, lighting and so forth in the real world are enhanced by computer-generated perceptual information. In this context an “augmented reality effect” comprises the collection of data, parameters, and other assets needed to apply a selected augmented reality experience to an image or a video feed. In some examples, augmented reality effects are provided by Snap, Inc. under the registered trademark LENSES. 
     In some examples, an augmented reality effect includes augmented reality (or “AR”) content configured to modify or transform image data presented within a GUI of the head-worn device in some way. For example, complex additions or transformations to the content images may be performed using AR effect data, such as adding rabbit ears to the head of a person, adding floating hearts with background coloring, altering the proportions of a person’s features, adding enhancements to landmarks in a scene being viewed on a head-worn device or many numerous other such transformations. This includes both real-time modifications that modify an image as it is captured using a camera associated with the head-worn device, which is then displayed by the head-worn device with the AR effect modifications, as well as modifications to stored content, such as video clips in a gallery that may be modified using AR effects. Similarly, real-time video capture may be used with an AR effect to show to a user of a head-worn device how video images currently being captured by sensors of a device would modify the captured data. Such data may simply be displayed on the screen and not stored in memory, the content captured by the device sensors may be recorded and stored in memory with or without the AR effect modifications (or both), or the content captured by the device sensors may be transmitted, with the AR effect modification, over the network  102  to a server or another device. 
     AR effects and associated systems and modules for modifying content using AR effects may thus involve detection of objects (e.g., faces, hands, bodies, cats, dogs, surfaces, objects), tracking of such objects as they leave, enter, and move around the field of view in video frames, and the modification or transformation of such objects as they are tracked. In various examples, different methods for achieving such transformations may be used. For example, some examples may involve generating a 3D mesh model of the object or objects, and using transformations and animated textures of the model within the video to achieve the transformation. In other examples, tracking of points on an object may be used to place an image or texture, which may be two dimensional or three dimensional, at the tracked position. In still further examples, neural network analysis of video frames may be used to place images, models, or textures in content (e.g., images or frames of video). AR effect data thus may include both the images, models, and textures used to create transformations in content, as well as additional modeling and analysis information needed to achieve such transformations with object detection, tracking, and placement. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced. 
         FIG.  1    is a perspective view of a head-worn device, in accordance with some examples. 
         FIG.  2    illustrates a further view of the head-worn device of  FIG.  1   , in accordance with some examples. 
         FIG.  3    is a block diagram illustrating a networked system  300  including details of the head-worn device of  FIG.  1   , in accordance with some examples. 
         FIG.  4    is a diagrammatic representation of a networked environment in which the present disclosure may be deployed, in accordance with some examples. 
         FIG.  5    illustrates an interface for music composition based on a grid of beats, in accordance with some examples. 
         FIG.  6 A  illustrates an interface for music creation based on a geometric loop, which can be used in a collaborative three-dimensional creation interface, in accordance with some examples. 
         FIG.  6 B  illustrates the interface of  FIG.  6 A  during playback, in accordance with some examples. 
         FIG.  7    illustrates an interface for music creation based on the geometric loop illustrated in  FIG.  6 A  and  FIG.  6 B , in accordance with some examples. 
         FIG.  8    illustrates a collaborative music creation session as viewed by a participant wearing a head-worn device, in accordance with some examples. 
         FIG.  9    illustrates an alternative interface for music creation based on the geometric loop illustrated in  FIG.  6 A  and  FIG.  6 B ,in accordance with some examples. 
         FIG.  10    illustrates a further alternative interface for music creation based on the geometric loop illustrated in  FIG.  6 A  and  FIG.  6 B , in accordance with some examples. 
         FIG.  11    is a flowchart illustrating operations performed by a head-worn device to provide or facilitate a shared music creation interface according to some examples. 
         FIG.  12    is a flowchart illustrating operations performed by a head-worn device to provide or facilitate a shared music creation interface according to some examples. 
         FIG.  13    is block diagram showing a software architecture within which the present disclosure may be implemented, in accordance with some examples. 
         FIG.  14    is a diagrammatic representation of a machine, in the form of a computer system within which a set of instructions may be executed for causing the machine to perform any one or more of the methodologies discussed, in accordance with some examples. 
     
    
    
     DETAILED DESCRIPTION 
     Known head-worn devices, such as AR spectacles, include a transparent or semi-transparent display that enables a user to see through the transparent or semi-transparent display to view the surrounding environment. Additional information or objects (e.g., virtual objects such as 3D renderings, images, video, text, and so forth) are shown on the display and appear as a part of, and/or overlaid upon, the surrounding environment to provide an augmented reality experience for the user. The display may for example include a waveguide that receives a light beam from a projector but any appropriate display for presenting augmented or virtual content to the wearer may be used. 
     AR spectacles can be used to create a shared environment in which a virtual object is positioned in a fixed location in the real world, viewable from the point of view of each of the users who are participating in the shared environment. The participants can then collaborate or compete in the shared environment. In some examples, a shared AR session in which a plurality of users via client devices can participate is hosted on a system that includes multiple head-worn devices, associated mobile devices and networked resources. The experience is synchronized and shared between the users, such that the actions of one user in the shared AR session can be synchronized and broadcast to the other users. 
     In some examples, a method of providing a music creation interface, executed by one or more processors in a head-worn device system including one or more display devices is provided. The method includes displaying a first geometric loop fixed relative to a location in the real world, the first geometric loop including a plurality of beat indicators, displaying a second geometric loop fixed relative to the location in the real world, the second geometric loop including a plurality of beat indicators and being spaced apart from the first geometric loop, displaying an interface includes a plurality of audio icons, receiving user selection to move a selected audio icon to a particular beat indicator on at least one of the first and second geometric loops, and displaying the selected audio icon at the particular beat indicator. 
     The method may also include rotating the first and second geometric loops and at least one play indicator relative to each other, and rendering a sound or note corresponding to the selected audio icon when the at least one play indicator is at the particular beat indicator or the selected audio icon. A joint augmented reality session may be initiated between a first head-mounted device and a second head-mounted device, the method further including displaying the first geometric loop via the first head-mounted device and the second head-mounted device in a fixed frame of reference fixed relative to the location in the real world, displaying the second geometric loop via the first head-mounted device and the second head-mounted device in the fixed frame of reference fixed relative to the location in the real world, detecting movement of the first head-mounted device and the second head-mounted device, and updating the display of the first geometric loop and the second geometric loop to account for the movement of the first head-mounted device and the second head-mounted device such that the first geometric loop and the second geometric loop appear to be stationary in the fixed frame of reference. 
     The method may also include determining a relative position and orientation between the music creation interface and the head-worn device system, and rendering audio corresponding to the selected audio icon in at least two speakers based on the relative position and orientation of the music creation interface and the head-worn device system. The at least one play indicator may remain stationary relative to the location in the real world while the first and second geometric loops rotate relative to the location in the real world. The first and second geometric loops may also remain stationary relative to the location in the real world while the at least one play indicator moves around the geometric loops. 
     A volume of the rendering of the audio may be changed depending on a perceived distance between the music creation interface and the head-worn device system, and the audio may be panned depending on the relative orientation between the music creation interface and the head-worn device system. 
     Also provided is a head-worn device system comprising one or more cameras one or more display devices, one or more processors; and a memory storing instructions that, when executed by the one or more processors, configure the system to perform operations to provide a music creation interface corresponding to the methods and features described above, including but not limited to displaying a first geometric loop fixed relative to a location in the real world, the first geometric loop including a plurality of beat indicators, displaying a second geometric loop fixed relative to the location in the real world, the second geometric loop including a plurality of beat indicators and being spaced apart from the first geometric loop, displaying an interface comprising a plurality of audio icons, receiving user selection to move a selected audio icon to a particular beat indicator on at least one of the first and second geometric loops, and displaying the selected audio icon at the particular beat indicator. 
     Also provided is a non-transitory computer-readable storage medium, the computer-readable storage medium including instructions that when executed by a head-worn device system including one or more display devices, cause the head-worn device system to perform operations to provide a music creation interface corresponding to the methods and features described above, including but not limited to, displaying a first geometric loop fixed relative to a location in the real world, the first geometric loop including a plurality of beat indicators, displaying a second geometric loop fixed relative to the location in the real world, the second geometric loop including a plurality of beat indicators and being spaced apart from the first geometric loop, displaying an interface includes a plurality of audio icons, receiving user selection to move a selected audio icon to a particular beat indicator on at least one of the first and second geometric loops, and displaying the selected audio icon at the particular beat indicator. 
     Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims. 
       FIG.  1    is perspective view of a head-worn device (e.g., glasses  100 ), in accordance with some examples. The glasses  100  can include a frame  102  made from any suitable material such as plastic or metal, including any suitable shape memory alloy. In one or more examples, the frame  102  includes a first or left optical element holder  104  (e.g., a display or lens holder) and a second or right optical element holder  106  connected by a bridge  112 . A first or left optical element  108  and a second or right optical element  110  can be provided within respective left optical element holder  104  and right optical element holder  106 . Each of the right optical element  110  and the left optical element  108  can be a lens, a display, a display assembly, or a combination of the foregoing. Any suitable display assembly can be provided in the glasses  100 . 
     The frame  102  additionally includes a left arm or temple piece  120  and a right arm or temple piece  122 . In some examples the frame  102  can be formed from a single piece of material so as to have a unitary or integral construction. 
     The glasses  100  can include a computing device, such as a computer  118 , which can be of any suitable type so as to be carried by the frame  102  and, in one or more examples, of a suitable size and shape, so as to be at least partially disposed in one of the temple piece  120  or the temple piece  122 . The computer  118  can include one or more processors with memory, wireless communication circuitry, and a power source. As discussed below, the computer  118  comprises low-power circuitry, high-speed circuitry, and a display processor. Various other examples may include these elements in different configurations or integrated together in different ways. Additional details of aspects of computer  118  may be implemented as illustrated by the data processor  302  discussed below. 
     The computer  118  additionally includes a battery  116  or other suitable portable power supply. In some examples, the battery  116  is disposed in left temple piece  120  and is electrically coupled to the computer  118  disposed in the right temple piece  122 . The glasses  100  can include a connector or port (not shown) suitable for charging the battery  116 , a wireless receiver, transmitter or transceiver (not shown), or a combination of such devices. 
     The glasses  100  include cameras  114 . Although two cameras are depicted, other examples contemplate the use of a single or additional (i.e., more than two) cameras. In one or more examples, the glasses  100  include any number of input sensors or other input/output devices in addition to the camera  114 . Such sensors or input/output devices can additionally include biometric sensors, location sensors, motion sensors, and so forth. 
     The glasses  100  may also include a touchpad  124  mounted to or integrated with one or both of the left temple piece  120  and right temple piece  122 . The touchpad  124  is generally vertically-arranged, approximately parallel to a user’s temple in some examples. As used herein, generally vertically aligned means that the touchpad is at least more vertical than horizontal, although potentially more vertical than that. Additional user input may be provided by one or more buttons  126 , which in the illustrated examples are provided on the outer upper edges of the left optical element holder  104  and right optical element holder  106 . The one or more touchpads  124  and buttons  126  provide a means whereby the glasses  100  can receive input from a user of the glasses  100 . 
       FIG.  2    illustrates the glasses  100  from the perspective of a wearer. For clarity, a number of the elements shown in  FIG.  1    have been omitted. As described in  FIG.  1   , the glasses  100  shown in  FIG.  2    include left optical element  108  and right optical element  110  secured within each of the left optical element holder  104  and the right optical element holder  106  respectively. 
     The glasses  100  include forward optical assembly  202  comprising a right projector  204  and a right near eye display  206 , and a forward optical assembly  210  comprising a left projector  212  and a near eye display  216 . 
     In some examples, the near eye displays are waveguides. The waveguides include reflective or diffractive structures (e.g., gratings and/or optical elements such as mirrors, lenses, or prisms). Light  208  emitted by the projector  204  encounters the diffractive structures of the waveguide of the near eye display  206 , which directs the light towards the right eye of a user to provide an image on or in the right optical element  110  that overlays the view of the real world seen by the user. Similarly, light  214  emitted by the projector  212  encounters the diffractive structures of the waveguide of the near eye display  216 , which directs the light towards the left eye of a user to provide an image on or in the left optical element  108  that overlays the view of the real world seen by the user. 
     It will be appreciated however that other display technologies or configurations may be provided that can display an image to a user in a forward field of view. For example, instead of a projector  204  and a waveguide, an LCD, LED or other display panel or surface may be provided instead. 
     In use, a wearer of the glasses  100  will be presented with information, content and various user interfaces on the near eye displays. As described in more detail below, the user can then interact with the glasses  100  using a touchpad  124  and/or the buttons  126 , in addition to providing voice inputs or touch inputs on an associated device, for example client device  328  illustrated in  FIG.  3   . 
       FIG.  3    is a block diagram illustrating a networked system  300  including details of the glasses  100 , in accordance with some examples. 
     The networked system  300  includes the glasses  100 , a client device  328 , and a server system  332 . The client device  328  may be a smartphone, tablet, phablet, laptop computer, access point, or any other such device capable of connecting with the glasses  100  using both a low-power wireless connection  336  and a high-speed wireless connection  334 . The client device  328  is connected to the server system  332  via the network  330 . The network  330  may include any combination of wired and wireless connections. The server system  332  may be one or more computing devices as part of a service or network computing system. The client device  328  and any elements of the server system  332  and network  330  may be implemented using details of the software architecture  1304  or the machine  1400  described in  FIG.  13    and  FIG.  14   . 
     The glasses  100  include a data processor  302 , displays  310 , one or more cameras  308 , and additional input/output elements  316 . The input/output elements  316  may include microphones, audio speakers, biometric sensors, additional sensors, or additional display elements integrated with the data processor  302 . Examples of the input/output elements  316  are discussed further with respect to  FIG.  13    and  FIG.  14   . For example, the input/output elements  316  may include any of I/O components  1406  including output components  1428 , motion components  1436 , and so forth. Examples of the displays  310  are discussed in  FIG.  2   . In the particular examples described herein, the displays  310  include a display for each one of a user’s left and right eyes. 
     The data processor  302  includes an image processor  306  (e.g., a video processor), a GPU &amp; display driver  338 , a tracking module  340 , an interface  312 , low-power circuitry  304 , and high-speed circuitry  320 . The components of the data processor  302  are interconnected by a bus  342 . 
     The interface  312  refers to any source of a user command that is provided to the data processor  302 . In one or more examples, the interface  312  is a physical button that, when depressed, sends a user input signal from the interface  312  to a low-power processor  314 . A depression of such button followed by an immediate release may be processed by the low-power processor  314  as a request to capture a single image, or vice versa. A depression of such a button for a first period of time may be processed by the low-power processor  314  as a request to capture video data while the button is depressed, and to cease video capture when the button is released, with the video captured while the button was depressed stored as a single video file. Alternatively, depression of a button for an extended period of time may capture a still image. In some examples, the interface  312  may be any mechanical switch or physical interface capable of accepting user inputs associated with a request for data from the camera  308 . In other examples, the interface  312  may have a software component, or may be associated with a command received wirelessly from another source, such as from the client device  328 . 
     The image processor  306  includes circuitry to receive signals from the camera  308  and process those signals from the camera  308  into a format suitable for storage in the memory  324  or for transmission to the client device  328 . In one or more examples, the image processor  306  (e.g., video processor) comprises a microprocessor integrated circuit (IC) customized for processing sensor data from the camera  308 , along with volatile memory used by the microprocessor in operation. 
     The low-power circuitry  304  includes the low-power processor  314  and the low-power wireless circuitry  318 . These elements of the low-power circuitry  304  may be implemented as separate elements or may be implemented on a single IC as part of a system on a single chip. The low-power processor  314  includes logic for managing the other elements of the glasses  100 . As described above, for example, the low-power processor  314  may accept user input signals from the interface  312 . The low-power processor  314  may also be configured to receive input signals or instruction communications from the client device  328  via the low-power wireless connection  336 . The low-power wireless circuitry  318  includes circuit elements for implementing a low-power wireless communication system. Bluetooth™ Smart, also known as Bluetooth™ low energy, is one standard implementation of a low power wireless communication system that may be used to implement the low-power wireless circuitry  318 . In other examples, other low power communication systems may be used. 
     The high-speed circuitry  320  includes a high-speed processor  322 , a memory  324 , and a high-speed wireless circuitry  326 . The high-speed processor  322  may be any processor capable of managing high-speed communications and operation of any general computing system needed for the data processor  302 . The high-speed processor  322  includes processing resources needed for managing high-speed data transfers on the high-speed wireless connection  334  using the high-speed wireless circuitry  326 . In certain examples, the high-speed processor  322  executes an operating system such as a LINUX operating system or other such operating system such as the operating system  1312  of  FIG.  13   . In addition to any other responsibilities, the high-speed processor  322  executing a software architecture for the data processor  302  is used to manage data transfers with the high-speed wireless circuitry  326 . In certain examples, the high-speed wireless circuitry  326  is configured to implement Institute of Electrical and Electronic Engineers (IEEE) 802.11 communication standards, also referred to herein as Wi-Fi. In other examples, other high-speed communications standards may be implemented by the high-speed wireless circuitry  326 . 
     The memory  324  includes any storage device capable of storing camera data generated by the camera  308  and the image processor  306 . While the memory  324  is shown as integrated with the high-speed circuitry  320 , in other examples, the memory  324  may be an independent standalone element of the data processor  302 . In certain such examples, electrical routing lines may provide a connection through a chip that includes the high-speed processor  322  from image processor  306  or the low-power processor  314  to the memory  324 . In other examples, the high-speed processor  322  may manage addressing of the memory  324  such that the low-power processor  314  will boot the high-speed processor  322  any time that a read or write operation involving the memory  324  is needed. 
     The tracking module  340  estimates a pose of the glasses  100 . For example, the tracking module  340  uses image data and corresponding inertial data from the camera  308  and the position components  1440 , as well as GPS data, to track a location and determine a pose of the glasses  100  relative to a frame of reference (e.g., real-world environment). The tracking module  340  continually gathers and uses updated sensor data describing movements of the glasses  100  to determine updated three-dimensional poses of the glasses  100  that indicate changes in the relative position and orientation relative to physical objects in the real-world environment. The tracking module  340  permits visual placement of virtual objects relative to physical objects by the glasses  100  within the field of view of the user via the displays  310 . 
     The GPU &amp; display driver  338  may use the pose of the glasses  100  to generate frames of virtual content or other content to be presented on the displays  310  when the glasses  100  are functioning in a traditional augmented reality mode. In this mode, the GPU &amp; display driver  338  generates updated frames of virtual content based on updated three-dimensional poses of the glasses  100 , which reflect changes in the position and orientation of the user in relation to physical objects in the user’s real-world environment. 
     One or more functions or operations described herein may also be performed in an application resident on the glasses  100  or on the client device  328 , or on a remote server. For example, one or more functions or operations described herein may be performed by one of the applications  1306  such as messaging application  13   46 . 
       FIG.  4    is a block diagram showing an example messaging system  400  for exchanging data (e.g., messages and associated content) over a network. The messaging system  400  includes multiple instances of a client device  328 , each of which hosts a number of applications, including a messaging client  402  and other applications  404 . Each messaging client  402  is communicatively coupled to other instances of the messaging client  402  (e.g., hosted on respective other client devices  328 ), a messaging server system  406  and third-party servers  408  via a network  330  (e.g., the Internet). A messaging client  402  can also communicate with locally-hosted applications  404  using Applications Program Interfaces (APIs). 
     A messaging client  402  is able to communicate and exchange data with other messaging clients  402  and with the messaging server system  406  via the network  330 . The data exchanged between messaging clients  402 , and between a messaging client  402  and the messaging server system  406 , includes functions (e.g., commands to invoke functions) as well as payload data (e.g., text, audio, video or other multimedia data). 
     The messaging server system  406  provides server-side functionality via the network  330  to a particular messaging client  402 . While certain functions of the messaging system  400  are described herein as being performed by either a messaging client  402  or by the messaging server system  406 , the location of certain functionality either within the messaging client  402  or the messaging server system  406  may be a design choice. For example, it may be technically preferable to initially deploy certain technology and functionality within the messaging server system  406  but to later migrate this technology and functionality to the messaging client  402  where a client device  328  has sufficient processing capacity. 
     The messaging server system  406  supports various services and operations that are provided to the messaging client  402 . Such operations include transmitting data to, receiving data from, and processing data generated by the messaging client  402 . This data may include message content, client device information, geolocation information, media augmentation and overlays, message content persistence conditions, social network information, and live event information, as examples. Data exchanges within the messaging system  400  are invoked and controlled through functions available via user interfaces (UIs) of the messaging client  402 . 
     Turning now specifically to the messaging server system  406 , an Application Program Interface (API) server  410  is coupled to, and provides a programmatic interface to, application servers  414 . The application servers  414  are communicatively coupled to a database server  416 , which facilitates access to a database  420  that stores data associated with messages processed by the application servers  414 . Similarly, a web server  424  is coupled to the application servers  414 , and provides web-based interfaces to the application servers  414 . To this end, the web server  424  processes incoming network requests over the Hypertext Transfer Protocol (HTTP) and several other related protocols. 
     The Application Program Interface (API) server  410  receives and transmits message data (e.g., commands and message payloads) between the client device  328  and the application servers  414 . Specifically, the Application Program Interface (API) server  410  provides a set of interfaces (e.g., routines and protocols) that can be called or queried by the messaging client  402  in order to invoke functionality of the application servers  414 . The Application Program Interface (API) server  410  exposes various functions supported by the application servers  414 , including account registration, login functionality, the sending of messages, via the application servers  414 , from a particular messaging client  402  to another messaging client  402 , the sending of media files (e.g., images or video) from a messaging client  402  to a messaging server  412 , and for possible access by another messaging client  402 , the settings of a collection of media data (e.g., story), the retrieval of a list of friends of a user of a client device  328 , the retrieval of such collections, the retrieval of messages and content, the addition and deletion of entities (e.g., friends) to an entity graph (e.g., a social graph), the location of friends within a social graph, and opening an application event (e.g., relating to the messaging client 402). 
     The application servers  414  host a number of server applications and subsystems, including for example a messaging server  412 , an image processing server  418 , and a social network server  422 . The messaging server  412  implements a number of message processing technologies and functions, particularly related to the aggregation and other processing of content (e.g., textual and multimedia content) included in messages received from multiple instances of the messaging client  402 . As will be described in further detail, the text and media content from multiple sources may be aggregated into collections of content (e.g., called stories or galleries). These collections are then made available to the messaging client  402 . Other processor and memory intensive processing of data may also be performed server-side by the messaging server  412 , in view of the hardware requirements for such processing. 
     The application servers  414  also include an image processing server  418  that is dedicated to performing various image processing operations, typically with respect to images or video within the payload of a message sent from or received at the messaging server  412 . 
     The social network server  422  supports various social networking functions and services and makes these functions and services available to the messaging server  412 . To this end, the social network server  422  maintains and accesses an entity graph within the database  420 . Examples of functions and services supported by the social network server  422  include the identification of other users of the messaging system  400  with which a particular user has relationships or is “following,” and also the identification of other entities and interests of a particular user. 
     Returning to the messaging client  402 , features and functions of an external resource (e.g., an application  404  or applet) are made available to a user via an interface of the messaging client  402 . In this context, “external” refers to the fact that the application  404  or applet is external to the messaging client  402 . The external resource is often provided by a third party but may also be provided by the creator or provider of the messaging client  402 . The messaging client  402  receives a user selection of an option to launch or access features of such an external resource. The external resource may be the application  404  installed on the client device  328  (e.g., a “native app”), or a small-scale version of the application (e.g., an “applet”) that is hosted on the client device  328  or remote of the client device  328  (e.g., on third-party servers  408 ). The small-scale version of the application includes a subset of features and functions of the application (e.g., the full-scale, native version of the application) and is implemented using a markup-language document. In some examples, the small-scale version of the application (e.g., an “applet”) is a web-based, markup-language version of the application and is embedded in the messaging client  402 . In addition to using markup-language documents (e.g., a .∗ml file), an applet may incorporate a scripting language (e.g., a .*js file or a .json file) and a style sheet (e.g., a .∗ss file). 
     In response to receiving a user selection of the option to launch or access features of the external resource, the messaging client  402  determines whether the selected external resource is a web-based external resource or a locally-installed application  404 . In some cases, applications  404  that are locally installed on the client device  328  can be launched independently of and separately from the messaging client  402 , such as by selecting an icon, corresponding to the application  404 , on a home screen of the client device  328 . As used herein, an icon can include one or both of text and graphic elements. Small-scale versions of such applications can be launched or accessed via the messaging client  402  and, in some examples, no or limited portions of the small-scale application can be accessed outside of the messaging client  402 . The small-scale application can be launched by the messaging client  402  receiving, from a third-party server  408  for example, a markup-language document associated with the small-scale application and processing such a document. 
     In response to determining that the external resource is a locally-installed application  404 , the messaging client  402  instructs the client device  328  to launch the external resource by executing locally-stored code corresponding to the external resource. In response to determining that the external resource is a web-based resource, the messaging client  402  communicates with the third-party servers  408  (for example) to obtain a markup-language document corresponding to the selected external resource. The messaging client  402  then processes the obtained markup-language document to present the web-based external resource within a user interface of the messaging client  402 . 
     The messaging client  402  can notify a user of the client device  328 , or other users related to such a user (e.g., “friends”), of activity taking place in one or more external resources. For example, the messaging client  402  can provide participants in a conversation (e.g., a chat session) in the messaging client  402  with notifications relating to the current or recent use of an external resource by one or more members of a group of users. One or more users can be invited to join in an active external resource or to launch a recently-used but currently inactive (in the group of friends) external resource. The external resource can provide participants in a conversation, each using respective messaging clients  402 , with the ability to share an item, status, state, or location in an external resource with one or more members of a group of users into a chat session. The shared item may be an interactive chat card with which members of the chat can interact, for example, to launch the corresponding external resource, view specific information within the external resource, or take the member of the chat to a specific location or state within the external resource. Within a given external resource, response messages can be sent to users on the messaging client  402 . The external resource can selectively include different media items in the responses, based on a current context of the external resource. 
       FIG.  5    illustrates an interface for music composition based on a grid of beats. As can be seen, a composing interface  500  includes a time axis  502  that is divided into a series of time increments or beats  504 . Different sounds or notes can be placed by the composer above selected beats in a number of tracks, such as track one  506 , track two  508  and track three  510 . Typically, when the composition is played, an indicator will sweep from left to right along the grid and the sounds or notes or percussion indicated in each track will be played at the appropriate beat. 
       FIG.  6 A  illustrates an interface for music creation based on a geometric time loop, which can be used in a collaborative three-dimensional composition interface as discussed further below. In this case, a music creation interface  600  includes at least one geometric loop  602  that is divided into a series of time increments illustrated by beat indicators  610 . Different sounds or notes can be placed by the composer above selected beat indicators  610  in the geometric loop  602 . In this case, notes or sounds are represented by three-dimensional virtual objects whose appearance (shape, color, texture and so forth) serve to identify the particular sound or note. In  FIG.  6   , a note or sound, as represented by note shape  604  has been placed over one of the beat indicators  610 . 
     Also shown is a playback indicator  606  indicating the current play time around the geometric loop  602 . The playback indicator  606  will be stationary at a start position (or other position around the geometric loop  602  if the creation has been paused) on the geometric loop  602  and when playback starts or resumes, the playback indicator  606  will move relative to and around the geometric loop  602 . In some examples, the playback indicator  606  sweeps around a stationary geometric loop  602  in the direction indicated by arrow  612 . Alternatively, the geometric loop  602  could rotate through or past a stationary playback indicator  606  in the direction shown by arrow  614 , or a combination of the two movements, as perceived by the composers, can be provided. 
     The playback indicator  606  in the example is an animating piece of geometry - a vertical bar that is animated around the loops to indicate active playback. In another example, a visual effect could be provided over the geometric loop  602  such as a material shader that animates over the top of the loop’s geometry or on a note shape  604  as the play indicator, to indicate active moving time on top of the loop geometry or the note shapes. 
       FIG.  6 B  illustrates the interface of  FIG.  6 A  during playback in some examples. As can be seen, when the composition is played the sounds or notes or percussion indicated by the note shape(s) (e.g., note shape  60   8 ) in the geometric loop  602  will be played at the appropriate time when that beat indicator is reached by the playback indicator  606  as it moves around the geometric loop  602 . 
     Although  FIG.  6 A  and  FIG.  6 B  show only one note shape  604  above one of the beat indicators  610 , note shapes can be stacked one above the other over a particular beat indicator so that more than one note or sound is played when that beat is reached by the play indicator  914 . Alternatively, multiple loops having the same number of beat indicators could be provided. Also, when viewed directly from above, the geometric loop  602  is circular. In the figures, geometric loops are shown as ellipses, since this is typically how they will be viewed (as circles seen in perspective view) by the participants in the shared AR session. Other geometric loop shapes could of course be provided. The term “geometric loop” is used herein to distinguish over logical or programming or other loops, but it will be appreciated that while the loop can be a geometric figure, an irregular or other planar or non-planar loop shape may be used. 
       FIG.  7    illustrates an interface for music creation based on the geometric loop illustrated in  FIG.  6 A  and  FIG.  6 B . The interface, referred to as music creation interface  700 , comprises a number of stacked geometric loops, including bottom loop  702 , middle loop  704  and top loop  706  in the illustrated example. More or less geometric loops could of course be provided. Also shown is a far-field reticle  720  that is displayed by the glasses  100  to assist with selection of note shapes as discussed in more detail below. Movement of the reticle  720  in the display can be effected by movement of a user’s finger on the touchpad  124  or the position of the reticle  720  can depend on movement of the participant’s head or a combination of both. Each participant in the shared session is provided with their own reticle  720  via the displays  310  of the glasses  100 . 
     Located at the bottom of the music creation interface  700  is a note selection interface  708  including a number of unique note shapes each representing a different sound or note, including note shape  710 , note shape  712 , note shape  714  and note shape  716 . In some examples, the note shapes in the note selection interface  708  are a grey or other bland color until they are selected by a participant using the reticle  720  or by gesture recognition based on the glasses  100  recognizing a hand or figure in the field of view of the glasses  100  at a position corresponding to one of the note shapes. Included in the note selection interface  708  is a “clear all” interface  718  that can be used to remove all note shapes positioned on one of the loops. In some examples, the note selection interface  708  is shared with all participants, in which case it appears in a stationary and consistent position in a real world frame of reference and can be acted upon by any of the participants, while in another example each participant is shown their own note selection interface  708 , in which case each note selection interface  708  is only visible to that participant and can rotate to face the participant as the participant moves around the music creation interface  700 . 
     As shown in the figure, in this example the bottom loop  702 , middle loop  704  and top loop  706  are the same size and are stacked one above the other so that they share a common central axis. Each of the loops includes a number of beat indicators  610 , with bottom loop  702  including four beat indicators  722 , middle loop  704  including five beat indicators  724  and top loop  706  including four beat indicators  726  in this example. The increment of time between each beat on all of the rings is the same in this example, but of course different time increments can be provided on any or all of the rings. 
     Since bottom loop  702  has four beat indicators  722  and the middle loop  704  has five beat indicators  724 , during playback in this case the playback indicators  606  (not shown in this figure) will reach the first beat in bottom loop  702  again, to restart bottom loop  702 , when the playback indicator  606  reaches the fifth beat in middle loop  704 . The loops and playback indicators  606  can thus become offset from one another during playback depending on the particular configuration and number of beat indicators. In another example, loops can be of the same duration but with different numbers of beat indicators, in which case the loops will not become offset during playback. For example, one four second loop could have eight beat indicators while another four second loop could have four beat indicators. 
     Note shapes that have been selected and placed on each loop are shown located above a corresponding beat in each loop. For example, bottom loop  702  includes note shape  712  on beat one, middle loop  704  includes note shape  710  on beat two, while top loop  706  includes note shape  716  on beat three and note shape  714  on beat four. 
     In some examples, the glasses  100  provide smart targeting of the reticle  720  for selection of a note shape in note selection interface  708  or on one of the loops. If the participant looks away from the music creation interface  700  then the reticle will fade out and vice versa. As the reticle approaches one of the note shapes, the glasses  100  can snap the reticle  720  to that note shape. Initial selection of the note shape can be indicated by a change in color of the note shape or by other visual effects, such as by providing a glow effect. Selection of that note shape can then be confirmed by receipt of a tap on the touchpad  124 . In the case of a note shape on a loop, a note shape to which the reticle has snapped can be deleted with a long press on the touchpad, or selected for movement to another location with a tap, and dropped at the new location with a further tap. 
     The music creation interfaces as described herein can be used in a number of different ways. In some examples, the music creation interface can be used to compose and play back musical compositions. In other examples, the music creation interface can be considered as a musical instrument that can be played live by a user to create a musical performance. In other examples, the music creation interface can be considered as a musical instrument or device on which a number of users can play collaboratively in a live performance or jam session. In the latter cases in particular, note shapes can be added to and removed from the loops at will by one or more users as the playback indicator  606  rotates with respect to the loops. 
       FIG.  8    illustrates a collaborative music composition session  800  as seen by a first participant wearing a head-worn device such as glasses  100 .  FIG.  8    includes items in the real world that are seen by the first participant, including a second participant  802 , a third participant  804 , a table  806  and a registration marker  808 . Overlaid over the real world elements on the displays  310  of the first participant’s glasses  100  is a version of the music creation interface  700 , including bottom loop  702 , middle loop  704  and note selection interface  708 . In  FIG.  8   , note shapes are yet to be placed on any of the loops. 
     Before playback, the music creation interface  700  is stationary. In other words, the loops are neither rotating relative to stationary real world objects such as the table nor is a playback indicator rotating around any of the loops. 
     Each participant has a view of the music creation interface  700  that is dependent on the position of their respective glasses  100 . Compared to the composition session  800  viewed by the first participant as illustrated, the second participant  802  is looking at the right hand side of the music creation interface  700  while the third participant  804  is looking at the left hand side of the music creation interface  700 . Were the first participant to move to the location of the third participant  804 , the music creation interface  700  would rotate in the first participant’s field of view so as to appear as fixed relative to the table  806  as if the music creation interface  700  were a real and not a virtual object. Collaboration by the participants is enhanced by providing a single, consistent music creation interface  700  that is located in the same perceived location for all participants. 
     Creation of this shared frame of reference can be accomplished in a number of ways. In some examples, a registration marker (such as registration marker  80   8 ) is placed in a relevant location, such as where the music creation interface  700  is to be used (on top of the table  806  in  FIG.  8   ). One of the glasses  100  (e.g., that of the creator of the shared session) captures an image of the registration marker, which is transmitted to the glasses that are being worn by the other participants. The other glasses also each detect and capture an image of the registration marker. The other glasses  100  then each determine a transformation between the first image and the images that each of the glasses  100 . A common coordinate frame is then determined using the transformation, and the shared composition session  800  is generated using the common coordinate frame. The registration marker remains visible to each of the glasses  100 , and can be used as a reference to update the pose of each of the glasses  100  as the participants move around in the environment. The view of the music creation interface  700  is then updated to reflect each new pose of the glasses  100 . 
     Other methods may be used to generate the shared frame of reference and, including for example 3D reconstruction and visual inertial odometry based on images captured by each pair of glasses  100  and based on signals or data received from inertial or other positional sensors located in each pair of glasses. Features identified using 3D reconstruction may also be compared with an existing point cloud model to locate and determine the pose of each pair of glasses in the real-world environment. 
     Once the shared composition session  800  has been established, each participant can manipulate the music creation interface  700  as discussed above with reference to  FIG.  5    to  FIG.  7   . 
     During playback, the audio generated by the glasses  100  or client device  328  is played back to each user through left and right speakers in or associated with the glasses  100 , or via earbuds or headphones. The audio is positioned using known spatial audio techniques so as to appear to be coming from the music creation interface  700  for each participant, based on the pose of the glasses  100  of each participant relative to the perceived location of the music creation interface  700  in the real world. 
     In some examples the audio is stereo positioning, so that if a participant turns left away from the perceived location of the music creation interface  700 , the audio will be panned so as to appear to be coming from the participant’s right. In another example, three-dimensional spatial audio can be implemented, so that, for example, if a participant bends their head towards the music creation interface  700 , the audio will be perceived to be coming from above their head. In the case of 3D spatial audio, the sounds generated by the notes on each loop can be positioned vertically in the audio scene based on the height of the loop on which each of the notes is located. Also, the level (volume) of the audio can be adjusted based on the distance of a participant from the music creation interface  700 , so as to be louder when closer and softer when further away. 
       FIG.  9    illustrates an alternative interface for music creation based on the geometric loop illustrated in  FIG.  6 A  and  FIG.  6 B . In this example, music creation interface  900  comprises three loops that are spaced apart horizontally and that are in the same or different vertical planes, that is located at the same height or different heights above the ground as perceived by the participants in the joint session. 
     In this example, first loop  902 , second loop  904  and third loop  906  each include beat indicators  908  as before, while each loop includes its own play indicator, namely play indicator  910 , play indicator  912 , play indicator  914  respectively, that will rotate relative to its corresponding loop as discussed above. A composing interface  500  (not shown in  FIG.  9   ), will also be provided as before. 
     Spatial audio is also be provided in this example, with the sounds from each individual loop being spatialized so as to be perceived to be coming from that loop. In some examples, the loops are selectable by a participant and can be dragged to a new vertical or horizontal position, permitting the creation of an audio scene or soundstage for the different loops. 
       FIG.  10    illustrates a further alternative interface for music creation based on the geometric loop illustrated in  FIG.  6 A  and  FIG.  6 B . In this example, music creation interface  1000  comprises three loops that are spaced apart vertically and horizontally with the exception of an intersection with a common vertical play indicator  1008  located at a starting beat indicator for each loop. 
     In this example, top loop  1002 , middle loop  1004 , bottom loop  1006 , each include multiple beat indicators as before, with a starting beat indicator  1014  for bottom loop  1006  being located directly below a starting beat indicator  1012  for middle loop  1004 , which is in turn located directly below a starting beat indicator  1010  for top loop  1002 , all being intersected by the common play indicator  100   8 . When playback is started, the loops may rotate around their individual central axes to maintain their intersection with the common play indicator  1008 , or the play indicator  1008  may split into individual play indicators that move around each loop as discussed above with reference to  FIG.  6 A  and  FIG.  6 B . A composing interface  500  (not shown in  FIG.  10   ), will also be provided as before. 
     Spatial audio is also be provided in this example, with the sounds from each individual loop being spatialized so as to be perceived to be coming from that loop. 
     While the playback indicators in the examples of  FIG.  9    and  FIG.  10    are animating pieces of geometry - a vertical bar that is animated around the loops to indicate active playback, in another example, a visual effect could be provided over the loops, such as a material shader that animates over the top of the loop’s geometry or on the note shapes as the play indicator, to indicate active moving time on top of the loop geometry or the note shapes. 
       FIG.  11    is a flowchart  1100  illustrating operations performed by glasses  100  to provide or facilitate a shared music creation interface according to some examples. For explanatory-purposes, the operations of the flowchart  1100  are described herein as occurring in serial, or linearly. However, multiple operations of the flowchart 1  100  may occur in parallel. In addition, the operations of the flowchart  1100  need not be performed in the order shown and/or one or more blocks of the flowchart  1100  need not be performed and/or can be replaced by other operations. 
     The operations illustrated in  FIG.  11    will typically execute on the data processor  302  and associated hardware in or associated with the glasses  100 . For the purposes of clarity, flowchart  1100  is discussed herein with reference to such an example. Various implementations are of course possible, with some of the operations taking place in client device  328  in an application such as messaging application  1346 , on server system  332 , or with one application on the client device  328  calling another application or SDK for required functionality. In some examples, the operations are performed jointly between messaging application  1346  running on the client device  328  and the data processor  302  and associated hardware in or associated with the glasses  100 . 
     The method starts at operation  1102  with initiation by the respective glasses  100  or client device  328  of a joint session involving all of the participants. The joint session may be initiated in response to an invitation transmitted by one of the participants from their client device  328  or glasses  100  to their friends or connections, or may be in response to a prompt that is triggered upon the detection of the proximity between the client devices  328  or glasses  100  of users who are friends or connections to each other, and are either at or near enough to be able to join in a reasonable time. 
     A joint frame of reference between the glasses  100  of the participants is then registered in operation  1104 . In some examples discussed in more detail above, this is done with reference to a registration marker  808  that has been placed in a convenient location. 
     Display of the music creation interface in the field of view of the participants’ glasses is then initiated in operation  1106 . In some cases, a default arrangement of geometric loops  602  and beat indicators  610  is displayed (including number of loops, spatial arrangement of loops, number of beat indicators on each loop and so forth), or a preferred initial arrangement or an in-process or existing composition can be loaded for editing or playback in response to user selection of existing defaults or compositions. In the case of a default arrangement, the number of beat indicators  610  on a particular geometric loop  602  can be adjusted by selecting a particular geometric loop  602  using the reticle  720  and adjusting its properties. Included in the display of the creation interface is a note selection interface  708  comprising a plurality of sound or note icons, in some examples in the form of the note shapes discussed above with reference to  FIG.  6 A ,  FIG.  6 B  and  FIG.  7   . 
     In operation  1114  and operation  1116  each of the participants’ glasses  100  update their display of the creation interface based on detecting a change in their relative poses in the fixed frame of reference, and compared to the music creation interface. Additionally, if any sounds or notes are being rendered, the spatialization of the corresponding audio is updated for a corresponding participant based on the change in pose of the particular participant’s glasses  100  in operation  1118 . This process is ongoing. 
     In operation  1108 , rotation of the geometric loops and at least one play indicator in the display of the music creation interface relative to each other commences as described above with reference to  FIG.  6 A  and  FIG.  6 B . In the example of flowchart  1100 , playback rotation occurs continuously to provide a dynamic creation experience, with the rendered sounds being updated as note shapes are added and removed and as their corresponding beat indicator is reached by a playback indicator. In this example, the loops are held stationary with respect to the frame of reference in the real world while the playback indicator(s) move around the loop, to permit easier positioning of note shapes on (stationary) beat indicators. 
     In operation  1110 , sounds or notes corresponding to sound or note icons are rendered when the at least one play indicator is at the particular beat indicator or the selected sound or note icon. 
     In operation  1112 , editing user inputs are received by the glasses  100  to create or modify a creation. This can include receiving input corresponding to the selection and movement of a sound or note icon to a particular beat indicator on a particular geometric loop  602 , the removal of a sound or note icon from its position on a particular geometric loop  602 , the rearrangement of sound or note icons on or between geometric loops  602 , and so forth. In response to receiving such inputs, the music creation interface is updated accordingly and the method returns to operation  1108  and playback and any editing continues. 
     At any time one or more of the participants may provide input to leave the joint session, and discard, save to, or delete the composition from, a repository associated with the particular participant, locally or in one of the application servers  414 . Additionally, a participant may provide input to share the composition. Upon receipt of a Save, Delete or Share input, the corresponding action is taken. In some examples, the composition may be shared via a message composed in a chat interface of a messaging application and sent to one or more of a participant’s connections or friends. In another example, the composition may be posted on a feed on a social networking site that is associated with the user. 
       FIG.  12    is a flowchart  1200  illustrating operations performed by glasses  100  to provide or facilitate a shared music creation interface according to some examples. For explanatory purposes, the operations of the flowchart  1200  are described herein as occurring in serial, or linearly. However, multiple operations of the flowchart  1200  may occur in parallel. In addition, the operations of the flowchart  1200  need not be performed in the order shown and/or one or more blocks of the flowchart  1200  need not be performed and/or can be replaced by other operations. 
     The operations illustrated in  FIG.  12    will typically execute on the data processor  302  and associated hardware in or associated with the glasses  100 . For the purposes of clarity, flowchart  1200  is discussed herein with reference to such an example. Various implementations are of course possible, with some of the operations taking place in client device  328  in an application such as messaging application  1346 , on server system  332 , or with one application on the client device  328  calling another application or SDK for required functionality. In some examples, the operations are performed jointly between messaging application  1346  running on the client device  328  and the data processor  302  and associated hardware in or associated with the glasses  100 . 
     The method starts at operation  1202  with initiation by the respective glasses  100  or client device  328  of a joint session involving all of the participants. The joint session may be initiated in response to an invitation transmitted by one of the participants from their client device  328  or glasses  100  to their friends or connections, or may be in response to a prompt that is triggered upon the detection of the proximity between the client devices  328  or glasses  100  of users who are friends or connections to each other, and are either at or near enough to be able to join in a reasonable time. 
     A joint frame of reference between the glasses  100  of the participants is then registered in operation  1204 . In some examples discussed in more detail above, this is done with reference to a registration marker  808  that has been placed in a convenient location. 
     Display of the music creation interface in the field of view of the participants’ glasses is then initiated in operation  1206 . In some cases, a default arrangement of geometric loops  602  and beat indicators  610  is displayed (including number of loops, spatial arrangement of loops, number of beat indicators on each loop and so forth), or a preferred initial arrangement or an in-process or existing composition can be loaded for editing or playback in response to user selection of existing defaults or compositions. In the case of a default arrangement, the number of beat indicators  610  on a particular geometric loop  602  can be adjusted by selecting a particular geometric loop  602  using the reticle  720  and adjusting its properties. Included in the display of the creation interface is a note selection interface  708  comprising a plurality of sound or note icons, in some examples in the form of the note shapes discussed above with reference to  FIG.  6 A ,  FIG.  6 B  and  FIG.  7   . 
     In operation  1216  and operation  1218  each of the participants glasses  100  update their display of the creation interface based on detecting a change in their relative poses in the fixed frame of reference, and compared to the music creation interface. Additionally, if any sounds or notes are being rendered, the spatialization of the corresponding audio is updated for a corresponding participant based on the change in pose of the particular participant’s glasses  100  in operation  1220 . This process is ongoing. 
     In operation  1208 , editing user inputs are received by the glasses  100  to create or modify a composition. This can include receiving input corresponding to the selection and movement of a sound or note icon to a particular beat indicator on a particular geometric loop  602 , the removal of a sound or note icon from its position on a particular geometric loop  602 , the rearrangement of sound or note icons on or between geometric loops  602 , and so forth. In response to receiving such inputs, the music creation interface is updated accordingly. 
     In some examples, user selection of a play input is then received at one of the participants’ glasses  100  in operation  1210 . In response in operation  1212 , the geometric loops and at least one play indicator in the display of the music creation interface are rotated relative to each other as described above with reference to  FIG.  6 A  and  FIG.  6 B , and sounds or notes corresponding to the sound or note icons are rendered in block  1214  when the at least one play indicator is at the particular beat indicator or the selected sound or note icon. The relative rotation of the play indicator(s) and geometric loops continue until a stop user input is received, at which time the method returns to operation  1208  or operation  1210  to receive further editing or play inputs. 
     At any time one or more of the participants may provide input to leave the joint session, and discard, save to, or delete the composition from, a repository associated with the particular participant, locally or in one of the application servers  414 . Additionally, a participant may provide input to share the composition. Upon receipt of a Save, Delete or Share input, the corresponding action is taken. In some examples, the composition may be shared via a message composed in a chat interface of a messaging application and sent to one or more of a participant’s connections or friends. In another example, the composition may be posted on a feed on a social networking site that is associated with the user. 
       FIG.  13    is a block diagram  1300  illustrating a software architecture  1304 , which can be installed on any one or more of the devices described herein. The software architecture  1304  is supported by hardware such as a machine  1302  that includes processors  1320 , memory  1326 , and I/O components  1338 . In this example, the software architecture  1304  can be conceptualized as a stack of layers, where each layer provides a particular functionality. The software architecture  1304  includes layers such as an operating system  1312 , libraries  1308 , frameworks  1310 , and applications  1306 . Operationally, the applications  1306  invoke API calls  1350  through the software stack and receive messages  1352  in response to the API calls  1350 . 
     The operating system  1312  manages hardware resources and provides common services. The operating system  1312  includes, for example, a kernel  1314 , services  1316 , and drivers  1322 . The kernel  1314  acts as an abstraction layer between the hardware and the other software layers. For example, the kernel  1314  provides memory management, processor management (e.g., scheduling), component management, networking, and security settings, among other functionality. The services  1316  can provide other common services for the other software layers. The drivers  1322  are responsible for controlling or interfacing with the underlying hardware. For instance, the drivers  1322  can include display drivers, camera drivers, BLUETOOTH® or BLUETOOTH® Low Energy drivers, flash memory drivers, serial communication drivers (e.g., Universal Serial Bus (USB) drivers), WI-FI® drivers, audio drivers, power management drivers, and so forth. 
     The libraries  1308  provide a low-level common infrastructure used by the applications  1306 . The libraries  1308  can include system libraries  1318  (e.g., C standard library) that provide functions such as memory allocation functions, string manipulation functions, mathematic functions, and the like. In addition, the libraries  1308  can include API libraries  1324  such as media libraries (e.g., libraries to support presentation and manipulation of various media formats such as Moving Picture Experts Group-4 (MPEG4), Advanced Video Coding (H.264 or AVC), Moving Picture Experts Group Layer-3 (MP3), Advanced Audio Coding (AAC), Adaptive Multi-Rate (AMR) audio codec, Joint Photographic Experts Group (JPEG or JPG), or Portable Network Graphics (PNG)), graphics libraries (e.g., an OpenGL framework used to render in two dimensions (2D) and three dimensions (3D) in a graphic content on a display), database libraries (e.g., SQLite to provide various relational database functions), web libraries (e.g., WebKit to provide web browsing functionality), and the like. The libraries  1308  can also include a wide variety of other libraries  1328  to provide many other APIs to the applications  1306 . 
     The frameworks  1310  provide a high-level common infrastructure that is used by the applications  1306 . For example, the frameworks  1310  provide various graphical user interface (GUI) functions, high-level resource management, and high-level location services. The frameworks  1310  can provide a broad spectrum of other APIs that can be used by the applications  1306 , some of which may be specific to a particular operating system or platform. 
     In an example, the applications  1306  may include a home application  1336 , a contacts application  1330 , a browser application  1332 , a book reader application  1334 , a location application  1342 , a media application  1344 , a messaging application  1346 , a game application  1348 , and a broad assortment of other applications such as third-party applications  13   40 . The applications  1306  are programs that execute functions defined in the programs. Various programming languages can be employed to create one or more of the applications  1306 , structured in a variety of manners, such as object-oriented programming languages (e.g., Objective-C, Java, or C++ or procedural programming languages (e.g., C or assembly language). In a specific example, the third-party applications  1340  (e.g., applications developed using the ANDROID™ or IOS™ software development kit (SDK) by an entity other than the vendor of the particular platform) may be mobile software running on a mobile operating system such as IOS™, ANDROID™, WINDOWS® Phone, or another mobile operating system. In this example, the third-party applications  1340  can invoke the API calls  1350  provided by the operating system  1312  to facilitate functionality described herein. 
       FIG.  14    is a diagrammatic representation of a machine  1400  within which instructions  1410  (e.g., software, a program, an application, an applet, an app, or other executable code) for causing the machine  1400  to perform any one or more of the methodologies discussed herein may be executed. For example, the instructions  1410  may cause the machine  1400  to execute any one or more of the methods described herein. The instructions  1410  transform the general, non-programmed machine  1400  into a particular machine  1400  programmed to carry out the described and illustrated functions in the manner described. The machine  1400  may operate as a standalone device or may be coupled (e.g., networked) to other machines. In a networked deployment, the machine  1400  may operate in the capacity of a server machine or a client machine in a server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine  1400  may comprise, but not be limited to, a server computer, a client computer, a personal computer (PC), a tablet computer, a laptop computer, a netbook, a set-top box (STB), a PDA, an entertainment media system, a cellular telephone, a smart phone, a mobile device, a head-worn device (e.g., a smart watch), a smart home device (e.g., a smart appliance), other smart devices, a web appliance, a network router, a network switch, a network bridge, or any machine capable of executing the instructions  1410 , sequentially or otherwise, that specify actions to be taken by the machine  1400 . Further, while only a single machine  1400  is illustrated, the term “machine” shall also be taken to include a collection of machines that individually or jointly execute the instructions  1410  to perform any one or more of the methodologies discussed herein. 
     The machine  1400  may include processors  1402 , memory  1404 , and I/O components  1406 , which may be configured to communicate with each other via a bus  1444 . In an example, the processors  1402  (e.g., a Central Processing Unit (CPU), a Reduced Instruction Set Computing (RISC) processor, a Complex Instruction Set Computing (CISC) processor, a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), an ASIC, a RadioFrequency Integrated Circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, a processor  1408  and a processor  1412  that execute the instructions  1410 . The term “processor” is intended to include multi-core processors that may comprise two or more independent processors (sometimes referred to as “cores”) that may execute instructions contemporaneously. Although  FIG.  14    shows multiple processors  1402 , the machine  1400  may include a single processor with a single core, a single processor with multiple cores (e.g., a multi-core processor), multiple processors with a single core, multiple processors with multiples cores, or any combination thereof. 
     The memory  1404  includes a main memory  1414 , a static memory  1416 , and a storage unit  1418 , both accessible to the processors  1402  via the bus  1444 . The main memory  1404 , the static memory  1416 , and storage unit  1418  store the instructions  1410  embodying any one or more of the methodologies or functions described herein. The instructions  1410  may also reside, completely or partially, within the main memory  1414 , within the static memory  1416 , within machine-readable medium  1420  within the storage unit  1418 , within at least one of the processors  1402  (e.g., within the processor’s cache memory), or any suitable combination thereof, during execution thereof by the networked system  300 . 
     The I/O components  1406  may include a wide variety of components to receive input, provide output, produce output, transmit information, exchange information, capture measurements, and so on. The specific I/O components  1406  that are included in a particular machine will depend on the type of machine. For example, portable machines such as mobile phones may include a touch input device or other such input mechanisms, while a headless server machine will likely not include such a touch input device. It will be appreciated that the I/O components  1406  may include many other components that are not shown in  FIG.  14   . In various examples, the I/O components  1406  may include output components  1428  and input components  1432 . The output components  1428  may include visual components (e.g., a display such as a plasma display panel (PDP), a light emitting diode (LED) display, a liquid crystal display (LCD), a projector, or a cathode ray tube (CRT)), acoustic components (e.g., speakers), haptic components (e.g., a vibratory motor, resistance mechanisms), other signal generators, and so forth. The input components  1432  may include alphanumeric input components (e.g., a keyboard, a touch screen configured to receive alphanumeric input, a photo-optical keyboard, or other alphanumeric input components), point-based input components (e.g., a mouse, a touchpad, a trackball, a joystick, a motion sensor, or another pointing instrument), tactile input components (e.g., a physical button, a touch screen that provides location and/or force of touches or touch gestures, or other tactile input components), audio input components (e.g., a microphone), and the like. 
     In further examples, the I/O components  1406  may include biometric components  1434 , motion components  1436 , environmental components  1438 , or position components  1440 , among a wide array of other components. For example, the biometric components  1434  include components to detect expressions (e.g., hand expressions, facial expressions, vocal expressions, body gestures, or eye tracking), measure biosignals (e.g., blood pressure, heart rate, body temperature, perspiration, or brain waves), identify a person (e.g., voice identification, retinal identification, facial identification, fingerprint identification, or electroencephalogram-based identification), and the like. The motion components  1436  include acceleration sensor components (e.g., accelerometer), gravitation sensor components, rotation sensor components (e.g., gyroscope), and so forth. The environmental components  1438  include, for example, illumination sensor components (e.g., photometer), temperature sensor components (e.g., one or more thermometers that detect ambient temperature), humidity sensor components, pressure sensor components (e.g., barometer), acoustic sensor components (e.g., one or more microphones that detect background noise), proximity sensor components (e.g., infrared sensors that detect nearby objects), gas sensors (e.g., gas detection sensors to detection concentrations of hazardous gases for safety or to measure pollutants in the atmosphere), or other components that may provide indications, measurements, or signals corresponding to a surrounding physical environment. The position components  1440  include location sensor components (e.g., a GPS receiver component), altitude sensor components (e.g., altimeters or barometers that detect air pressure from which altitude may be derived), orientation sensor components (e.g., magnetometers), and the like. 
     Communication may be implemented using a wide variety of technologies. The I/O components  1406  further include communication components  1442  operable to couple the networked system  300  to a network  1422  or devices  1424  via a coupling  1430  and a coupling  1426 , respectively. For example, the communication components  1442  may include a network interface component or another suitable device to interface with the network  1422 . In further examples, the communication components  1442  may include wired communication components, wireless communication components, cellular communication components, Near Field Communication (NFC) components, Bluetooth ®  components (e.g., Bluetooth ®  Low Energy), Wi-Fi ®  components, and other communication components to provide communication via other modalities. The devices  1424  may be another machine or any of a wide variety of peripheral devices (e.g., a peripheral device coupled via a USB). 
     Moreover, the communication components  1442  may detect identifiers or include components operable to detect identifiers. For example, the communication components  1442  may include Radio Frequency Identification (RFID) tag reader components, NFC smart tag detection components, optical reader components (e.g., an optical sensor to detect one-dimensional bar codes such as Universal Product Code (UPC) bar code, multi-dimensional bar codes such as Quick Response (QR) code, Aztec code, Data Matrix, Dataglyph, MaxiCode, PDF417, Ultra Code, UCC RSS-2D bar code, and other optical codes), or acoustic detection components (e.g., microphones to identify tagged audio signals). In addition, a variety of information may be derived via the communication components  1442 , such as location via Internet Protocol (IP) geolocation, location via Wi-Fi® signal triangulation, location via detecting an NFC beacon signal that may indicate a particular location, and so forth. 
     The various memories (e.g., memory  1404 , main memory  1414 , static memory  1416 , and/or memory of the processors  1402 ) and/or storage unit  1418  may store one or more sets of instructions and data structures (e.g., software) embodying or used by any one or more of the methodologies or functions described herein. These instructions (e.g., the instructions  1410 ), when executed by processors  1402 , cause various operations to implement the disclosed examples. 
     The instructions  1410  may be transmitted or received over the network  1422 , using a transmission medium, via a network interface device (e.g., a network interface component included in the communication components  1442 ) and using any one of a number of well-known transfer protocols (e.g., hypertext transfer protocol (HTTP)). Similarly, the instructions  1410  may be transmitted or received using a transmission medium via the coupling  1426  (e.g., a peer-to-peer coupling) to the devices  1424 . 
     A “carrier signal” refers to any intangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine, and includes digital or analog communications signals or other intangible media to facilitate communication of such instructions. Instructions may be transmitted or received over a network using a transmission medium via a network interface device. 
     A “client device” refers to any machine that interfaces to a communications network to obtain resources from one or more server systems or other client devices. A client device may be, but is not limited to, a mobile phone, desktop computer, laptop, portable digital assistants (PDAs), smartphones, tablets, ultrabooks, netbooks, laptops, multi-processor systems, microprocessor-based or programmable consumer electronics, game consoles, set-top boxes, or any other communication device that a user may use to access a network. 
     A “communication network” refers to one or more portions of a network that may be an ad hoc network, an intranet, an extranet, a virtual private network (VPN), a local area network (LAN), a wireless LAN (WLAN), a wide area network (WAN), a wireless WAN (WWAN), a metropolitan area network (MAN), the Internet, a portion of the Internet, a portion of the Public Switched Telephone Network (PSTN), a plain old telephone service (POTS) network, a cellular telephone network, a wireless network, a Wi-Fi® network, another type of network, or a combination of two or more such networks. For example, a network or a portion of a network may include a wireless or cellular network and the coupling may be a Code Division Multiple Access (CDMA) connection, a Global System for Mobile communications (GSM) connection, or other types of cellular or wireless coupling. In this example, the coupling may implement any of a variety of types of data transfer technology, such as Single Carrier Radio Transmission Technology (1xRTT), Evolution-Data Optimized (EVDO) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for GSM Evolution (EDGE) technology, third Generation Partnership Project (3GPP) including 3G, fourth generation wireless (4G) networks, Universal Mobile Telecommunications System (UMTS), High Speed Packet Access (HSPA), Worldwide Interoperability for Microwave Access (WiMAX), Long Term Evolution (LTE) standard, others defined by various standard-setting organizations, other long-range protocols, or other data transfer technology. 
     A “component” refers to a device, physical entity, or logic having boundaries defined by function or subroutine calls, branch points, APIs, or other technologies that provide for the partitioning or modularization of particular processing or control functions. Components may be combined via their interfaces with other components to carry out a machine process. A component may be a packaged functional hardware unit designed for use with other components and a part of a program that usually performs a particular function of related functions. Components may constitute either software components (e.g., code embodied on a machine-readable medium) or hardware components. A “hardware component” is a tangible unit capable of performing certain operations and may be configured or arranged in a certain physical manner. In various examples, one or more computer systems (e.g., a standalone computer system, a client computer system, or a server computer system) or one or more hardware components of a computer system (e.g., a processor or a group of processors) may be configured by software (e.g., an application or application portion) as a hardware component that operates to perform certain operations as described herein. A hardware component may also be implemented mechanically, electronically, or any suitable combination thereof. For example, a hardware component may include dedicated circuitry or logic that is permanently configured to perform certain operations. A hardware component may be a special-purpose processor, such as a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC). A hardware component may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations. For example, a hardware component may include software executed by a general-purpose processor or other programmable processor. Once configured by such software, hardware components become specific machines (or specific components of a machine) uniquely tailored to perform the configured functions and are no longer general-purpose processors. It will be appreciated that the decision to implement a hardware component mechanically, in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software), may be driven by cost and time considerations. Accordingly, the phrase ″hardware component″(or “hardware-implemented component”) should be understood to encompass a tangible entity, be that an entity that is physically constructed, permanently configured (e.g., hardwired), or temporarily configured (e.g., programmed) to operate in a certain manner or to perform certain operations described herein. Considering examples in which hardware components are temporarily configured (e.g., programmed), each of the hardware components need not be configured or instantiated at any one instance in time. For example, where a hardware component comprises a general-purpose processor configured by software to become a special-purpose processor, the general-purpose processor may be configured as respectively different special-purpose processors (e.g., comprising different hardware components) at different times. Software accordingly configures a particular processor or processors, for example, to constitute a particular hardware component at one instance of time and to constitute a different hardware component at a different instance of time. Hardware components can provide information to, and receive information from, other hardware components. Accordingly, the described hardware components may be regarded as being communicatively coupled. Where multiple hardware components exist contemporaneously, communications may be achieved through signal transmission (e.g., over appropriate circuits and buses) between or among two or more of the hardware components. In examples in which multiple hardware components are configured or instantiated at different times, communications between such hardware components may be achieved, for example, through the storage and retrieval of information in memory structures to which the multiple hardware components have access. For example, one hardware component may perform an operation and store the output of that operation in a memory device to which it is communicatively coupled. A further hardware component may then, at a later time, access the memory device to retrieve and process the stored output. Hardware components may also initiate communications with input or output devices, and can operate on a resource (e.g., a collection of information). The various operations of example methods described herein may be performed, at least partially, by one or more processors that are temporarily configured (e.g., by software) or permanently configured to perform the relevant operations. Whether temporarily or permanently configured, such processors may constitute processor-implemented components that operate to perform one or more operations or functions described herein. As used herein, “processor-implemented component” refers to a hardware component implemented using one or more processors. Similarly, the methods described herein may be at least partially processor-implemented, with a particular processor or processors being an example of hardware. For example, at least some of the operations of a method may be performed by one or more processors or processor-implemented components. Moreover, the one or more processors may also operate to support performance of the relevant operations in a “cloud computing” environment or as a “software as a service” (SaaS). For example, at least some of the operations may be performed by a group of computers (as examples of machines including processors), with these operations being accessible via a network (e.g., the Internet) and via one or more appropriate interfaces (e.g., an API). The performance of certain of the operations may be distributed among the processors, not only residing within a single machine, but deployed across a number of machines. In some examples, the processors or processor-implemented components may be located in a single geographic location (e.g., within a home environment, an office environment, or a server farm). In other examples, the processors or processor-implemented components may be distributed across a number of geographic locations. 
     A “computer-readable medium” refers to both machine-storage media and transmission media. Thus, the terms include both storage devices/media and carrier waves/modulated data signals. The terms “machine-readable medium,” “computer-readable medium” and “device-readable medium” mean the same thing and may be used interchangeably in this disclosure. 
     An “ephemeral message” refers to a message that is accessible for a time-limited duration. An ephemeral message may be a text, an image, a video and the like. The access time for the ephemeral message may be set by the message sender. Alternatively, the access time may be a default setting or a setting specified by the recipient. Regardless of the setting technique, the message is transitory. 
     A “machine-storage medium” refers to a single or multiple storage devices and/or media (e.g., a centralized or distributed database, and/or associated caches and servers) that store executable instructions, routines and/or data. The term shall accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media, including memory internal or external to processors. Specific examples of machine-storage media, computer-storage media and/or device-storage media include non-volatile memory, including by way of example semiconductor memory devices, e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), FPGA, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks The terms “machine-storage medium,” “device-storage medium,” “computer-storage medium” mean the same thing and may be used interchangeably in this disclosure. The terms “machine-storage media,” “computer-storage media,” and “device-storage media” specifically exclude carrier waves, modulated data signals, and other such media, at least some of which are covered under the term “signal medium.” 
     A “processor” refers to any circuit or virtual circuit (a physical circuit emulated by logic executing on an actual processor) that manipulates data values according to control signals (e.g., “commands”, “op codes”, “machine code”, and so forth) and which produces corresponding output signals that are applied to operate a machine. A processor may, for example, be a Central Processing Unit (CPU), a Reduced Instruction Set Computing (RISC) processor, a Complex Instruction Set Computing (CISC) processor, a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Radio-Frequency Integrated Circuit (RFIC) or any combination thereof. A processor may further be a multi-core processor having two or more independent processors (sometimes referred to as “cores”) that may execute instructions contemporaneously. 
     A “signal medium” refers to any intangible medium that is capable of storing, encoding, or carrying the instructions for execution by a machine and includes digital or analog communications signals or other intangible media to facilitate communication of software or data. The term “signal medium” shall be taken to include any form of a modulated data signal, carrier wave, and so forth. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a matter as to encode information in the signal. The terms “transmission medium” and “signal medium” mean the same thing and may be used interchangeably in this disclosure. 
     Changes and modifications may be made to the disclosed examples without departing from the scope of the present disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure, as expressed in the following claims.