Patent Publication Number: US-2010131675-A1

Title: System and method for secured distribution of media assets from a media server to client devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND 
     1. Field of Invention 
     This invention relates to a media delivery system, specifically to system and method for secured distributions of media assets from a media server to client devices. 
     2. Description of Prior Art 
     Due to the increasing capacity and capability of personal computers, it has become popular to use a personal computer connected to the Internet as a repository for media assets such as for example, songs and multi-media clips. The media assets are typically compressed to a desired format such as MP3 (Motion Picture Expert&#39;s Group Layer 3) for songs for digital distribution through the Internet. Handheld media players are used to download media assets from the personal computer. Examples of handheld media players are the iPod from Apple, Inc. of Cupertino, Calif., Zen from Creative Technology Ltd, Singapore and the Zune from Microsoft Inc of Redmond, Wash. The media assets are typically acquired with media management applications, such as iTunes software, which is a product from Apple Inc. The handheld media players have gained popularity due to its capability to store large number of media assets in a device, which can be put into a user&#39;s pocket when he or she is moving around. 
     Downloading compressed media assets from the personal computer to a handheld media player may be carried out via a FIREWIRE (IEEE 1394 type of connection). US patent publications 2004/0224638 and 2008/0125031 by Fadell et al. disclose a media player system with wireless communication capabilities to other media devices. US patent application publication 2008/0031210 by Abhishek et al. discloses a portable media player device capable of operating in a wireless network. Neighbor portable media player devices in an ad hoc network can be discovered by the wireless portable media player device. 
     There are numerous other existing electronic devices that have been used to deliver media assets to users directly. Examples are high fidelity (HiFi) audio system for music, digital television system with a set top box for video and car media system for radio and music. Although a significant number of media assets are delivered to users via these devices, the opportunities have not been explored for distributing media assets to other media devices. A user, enjoying a song played by a HiFi system, may be motivated to purchase and store the song in his or her handheld media player. 
     Therefore, what is desired is a media delivery system that leveraging existing media asset delivery devices, such as for example, a HiFi audio system, a digital TV and a car media system to distribute a media asset being broadcasted or being played to other media devices controlled by a user. 
     SUMMARY OF THE INVENTION 
     A media delivery system includes a media server and at least one media client device. The media server may be a conventional media delivery apparatus with an added data compression unit and a wireless communication unit. When a media asset with a data format is being played, the same asset is compressed and is transmitted wirelessly to the client devices. The client device may be a media player with an additional wireless communication capability. A client device or multiple client devices and the server may form a wireless network. The client devices are connected to the server when the devices are in the proximity. The wireless communication network is an ad hoc network. 
     The client device receives the compressed media asset. According to one implementation of the present invention, the metadata of the asset such as the title and artists of the asset are displayed on a display screen of the client device with an option for the user to purchase the asset. The compressed asset may be encrypted before it is transmitted from the server. The encryption may be based on a public/private key system. A public key is distributed to the server. The asset can be decrypted after the purchasing process is completed and a private key is received. When the client device is connected to the Internet, the purchasing can be conducted through an on-line payment facility. 
     The invention relates, in one embodiment, to a HiFi audio system with an added data compression unit and a wireless communication unit. According to one implementation, the wireless communication is conforming to the Bluetooth type of standard (IEEE 802.11). When a song is being played in an uncompressed format by the HiFi system, the asset is being compressed to MP3 format and is encrypted and is transmitted wirelessly to client devices. When a user with a handheld media player as the client device approaches the HiFi system as the server, a wireless communication link is established. The handheld media player receives the MP3 formatted song and stores the data in its file storage system. The user will notify that the metadata of the song is displayed on its display screen. A purchase option may be displayed. The option may be with a “yes” or “no” type. The user&#39;s selection of “yes” will lead to an on-line payment process if the client device is connected to the Internet. The asset can be decrypted after receiving a private key. The decrypted asset may be stored in the file storage system of the handheld media player. 
     The invention relates to, in another embodiment, a digital TV with a set top box. When a video programming in an uncompressed format is delivered to the TV terminal for displaying, the file is compressed to MP4 (Moving Picture Experts Group under the formal standard ISO/IEC 14496) and is transmitted wirelessly to MP4 players. The video file in MP4 form may be encrypted before the transmission. The MP4 player receives the video file. A user may decide to purchase the asset. The video file is stored in the file storage system of the MP4 player after the decryption. Some assets may be acquired freely. In such a case, encryption/decryption may not be needed. 
     Various other embodiments based upon similar inventive concept by using such as a vehicle media system, an advertisement display panel, a theater media system and a concert media recording and processing system as the media server and by using a HiFi audio system and a personal computing device as the client device will be discussed in details in the following sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention and its various embodiments, and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1   a  is a schematic diagram of a media delivery system including a media server and a media client device. They are connected wirelessly to form an ad hoc network. 
         FIG. 1   b  is a schematic diagram of an embodiment of the media delivery system, wherein the media server is based upon a HiFi audio system and the media client device upon a handheld media player. 
         FIG. 1   c  is a schematic diagram of an embodiment of the media delivery system, wherein the media server is based upon a digital TV system with a set top box and the media client device upon a handheld media player or a personal computer or a HiFi audio system. 
         FIG. 1   d  is a schematic diagram of an embodiment of the media delivery system, wherein the media server is based upon a vehicle media system and the media client device upon a handheld media player. 
         FIG. 1   e  is a schematic diagram of an embodiment of the media delivery system, wherein the media server is based upon a handheld media player and the media client device upon another handheld media player. 
         FIG. 1   f  is a schematic diagram of an embodiment of the media delivery system, wherein the media server is based upon an electronic advertising display panel and the media client device upon a handheld media player. 
         FIG. 1   g  is a schematic diagram of an embodiment of the media delivery system, wherein the media server is based upon a theater audio/video system and the media client device upon a handheld media player. 
         FIG. 1   h  is a schematic diagram of an embodiment of the media delivery system, wherein the media server is based upon a concert media recording and processing system and the media client device upon a handheld media player. 
         FIG. 2  is a schematic functional block of a HiFi audio system as the media server according to one embodiment of the present invention. 
         FIG. 3  is a schematic functional block of a handheld media player as the media client device according to one embodiment of the present invention. 
         FIG. 4  shows a representative handheld media player as a media client device. The display screen of the device illustrates that the metadata of the compressed media asset is displayed and an option of purchase is offered to the user by selecting a “yes” or “no” according to one implementation of the present invention. 
         FIG. 5  shows a flow diagram of the operation that an uncompressed media asset is being played by the media server while the asset is compressed, encrypted and transmitted wirelessly to the media client device. 
         FIG. 6  shows a flow diagram of the operation that an uncompressed media asset is being played by the media server while the asset is compressed, encrypted and transmitted wirelessly in a repeatedly manner to the media client device. 
         FIG. 7   a  shows a schematic diagram of uncompressed and compressed media data is divided into multiple data packets. 
         FIG. 7   b  shows a flow diagram of the operation that an uncompressed media asset is being played by the media server while the asset is compressed, encrypted and transmitted wirelessly to the media client device. The compressed asset is divided into multiple data packets which are transmitted sequentially in a synchronized manner as the uncompressed asset is being played. 
         FIG. 8  shows a flow diagram of the operation that a compressed and encrypted media asset is received by a media client device and is purchased by the user of the client device. 
         FIG. 9  shows a flow diagram of the payment process of a client device when a media asset is received from the media server. 
         FIG. 10  shows a flow diagram of the operation of an embodiment of the present invention, wherein the media server is a recording and data processing system for a concert and the media client devices are many handheld media players. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described in detail with references to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present invention. 
     The term “media player” generally refers to computing devices that are dedicated to processing media such as audio, video or other images, as for example, music players, game players, video players, video recorders, digital cameras, and the like. In some cases, the media players contain single functionality (e.g., a media player dedicated to playing music) and in other cases the media players contain multiple functionality (e.g., a media player that plays music, displays video, stores pictures and the like). In either case, these devices are generally portable so as to allow a user to listen to music, play games or video or take pictures wherever the user travels. 
     The term “media server” generally refers to computing devices that are used to processing media. It may be a general purpose computer and it may also be a dedicated media player such as a HiFi audio system or a digital television system with a set top box. A media server has a functionality to transmit a media asset to other media devices. 
     The term “media client device” generally refers to computing devices that receive media assets from media servers. The media client devices are in general media players with the capability to communicate or at least the capability to receive information from the media servers. The media client devices may be portable in some cases. The media client devices may not be portable in other cases. 
     The term “media asset” generally refers to media files such as text, audio, video, TV programs, images, photos, web pages, multi-media files and the likes. Some media assets may be protected by the copy right. For digital right management purposes, it may be desirable to encrypt the media assets during transmission over a wireless link or a wireless network. A public/private key system as well known in the art may be used. 
     The term “wireless network” generally refers to computer network that is wireless and is commonly associated with a telecommunication network whose interconnections between nodes is implemented without use of wires. In some implementations, Wireless Personal Area Network (WPAN) is used to connect media servers and media client devices within a relatively small area, generally within reach of a person. For example, the wireless communication network may conform to the Bluetooth type of standard (IEEE 802.11) or to the Zigbee type of standard (IEEE 802.15.4). In other implementations, the wireless network can also take form of a WiFi (IEEE 802.11b or 802.11g) network. Yet in some other implementations, FM, RF, IR (infrared), UWB (ultra wide band, IEEE 802.15.4a) and visible light links may be used to connect the media servers and the media client devices. 
     As shown in  FIG. 1   a , a media delivery system  100  comprises a media server  102  and a media client device  104 . The server  102  and the client device  104  are connectable by a wireless communication network interface  106 . According to a preferred embodiment, the wireless communication interface conforms to the Bluetooth type of standard (IEEE 802.11). Both the server and the client device may include a transceiver (for two way communications). Alternatively, the server may include a transmitter and the client device may include a receiver (for one way communication). An antenna is required and may be fully contained within the server and the client device. 
     Although only one server and one client device is shown in the figure, the inventive concept can be extended to multiple servers and multiple client devices. The servers and client devices may form an ad hoc wireless network. The network is the WPAN in a preferred implementation. Both server and client device may also be connected to other communication network such as the Internet. The media server  102  may be used to deliver a media asset to a user directly. The media asset may be in an uncompressed format. The media asset may also be in a compressed format such as MP3 for a song. The present invention is characterized by that the media asset being played by the server and the one being transmitted over the wireless link or network may be in different formats. For example, a media asset in uncompressed format may be played by the server  102  while the asset in the compressed form is being transmitted by the server  102  and being received by the client device  104 . 
       FIG. 1   b  shows a schematic diagram of one embodiment of the present invention. The media server is based upon a HiFi audio system  108 . The system has a data compression and encryption unit  109 . The client device  110  is based upon a handheld media player. The HiFi audio system  108  and the handheld media player  110  are connectable via a wireless communication interface  112 . The Bluetooth type of communication (IEEE 802.11) a preferred embodiment although other communication links are possible as described previously. Songs are now used as exemplary media assets in the description without limiting the scope of the present invention. The audio data for the song is compressed by a processor in the HiFi audio system before it is encrypted for the transmission. The compressed audio data may take a format of MP3 or other formats as well known in the art. The digital right may be managed by encrypting the compressed audio data. Typically, this requires some forms of authentication, and is preferably based on a public key/private key system. In one embodiment, the audio data is encrypted by a public key before the transmission. The handheld media player  110  (client device) with the Bluetooth communication interface receives the encrypted audio data. The audio data is stored in a file storage system of the handheld media player  110 . The metadata is then displayed on a display screen of the player. The user may decide to purchase the asset if it is encrypted or the user may decide to abandon the asset after viewing the metadata. After the user purchases the song, the audio data is decrypted based on a received private key from the on-line merchandiser and is stored in the file storage system for the future usages. 
     It should be emphasized that when a song is being played by the HiFi audio system  108  in the uncompressed format, the audio data is being compressed to the MP3 format in the same time. The compressed data is encrypted and is transmitted over the wireless link or network. The present invention is characterized by that the audio data being played and the audio data being transmitted may take different formats although they represent the same media asset. The present invention allows that a user favored song is purchased and is stored in the handheld media player conveniently when the user is enjoying a high quality song via the HiFi system. 
       FIG. 1   c  shows a schematic diagram of another embodiment of the present invention. The media server is based upon a digital television (TV) system  113  comprising a TV terminal  114  and a set top box  116 . The set top box  116  includes a data compression and encryption unit  117 . The client device is based upon a handheld media player  118 . The digital TV system  113  and the handheld player  118  are connectable through the wireless communication interface  121  as shown in the figure. The communication interface may be a wireless broadband communication protocol such as WiFi (IEEE 802.11b or 802.11g) or UWB (IEEE 802.15.4a) enabling transmitting video data in a reasonable time. The set top box  116  is with a wireless transmitter or a transceiver. The handheld media player  118  is with a wireless receiver or a transceiver. The set top box  116  may also be connected to other communication networks such as the Internet. The handheld media player  118  may also be connected to the Internet directly or through another server such as a general purpose computing device. A video programming transmitted from the set top box  116  is broadcasted in the TV terminal  114 . The video file may be compressed by the set top box to a desired format such as MP4. The compressed video programming may be encrypted based on a public/private key system as described previously and be transmitted to the handheld media player  118  wirelessly. The handheld media player  118  receives the video programming in MP4 format and may display its metadata on a display screen of the player. The user may decide to purchase the program and to decrypt the asset based on received private key and store it in the file storage system of the handheld player  118 . Some video programs may not be copy right protected. In such a case, the encryption/decryption steps may not be required and the video programming is received and stored in the media client device. 
     In another implementation of the current embodiment, the client device may be based upon a personal computer  119  as shown in the figure. The compressed video programming may be received by the personal computer  119  and be stored in its memory system. The user may purchase the asset on-line when the personal computer is connected to the Internet. After the purchasing, the programming is decrypted based on the received private key and the user can use it accordingly with a standard MP4 player in the computer. 
     In yet another implementation of the current embodiment, the client device may be a HiFi audio system  121 . The audio portion of a multi-media programming may be compressed and encrypted by the set top box  116  and be received by the HiFi audio system  120  and be stored in its memory system. The user may purchase the asset and decrypt and store it for future usage through using an input device such as a remote control of the HiFi audio system  120 . 
       FIG. 1   d  is a schematic diagram of another embodiment of the present invention. The media server is a vehicle media system  122 . The vehicle media system  122  comprises typically a radio and a music player including a compact disk driver. Some car media systems have been integrated with a plug-in handheld media player such as an iPod from Apple. According to one implementation of the present invention, a data compression and encryption unit  123  is included in the system. The client device is a handheld media player  124 . The vehicle media system  122  and the player  124  are connectable through a wireless communication interface  126 , which may be conformed to the Bluetooth type of standard (IEEE 802.11) in a preferred embodiment of the present invention. When connected, the vehicle media system  122  and the handheld media players may form a wireless network. Similarly, other wireless communication links or networks as described previously are also possible. When a driver or a passenger carrying a handheld media player  124  in a vehicle, a wireless communication link is established between the vehicle media system  122  and the player  124 . When a song as an exemplary case for a media asset is played via the compact disk driver or broadcasted by employing digital broadcast system, the audio data is compressed to MP3 format in a preferred implementation and be encrypted before it is transmitted to the handheld media player  124  through the Bluetooth communication interface  126 . The handheld media player  124  receives the song in MP3 format and stores the asset in its file storage system. The user may decide to purchase the asset. The data will be decrypted if the purchasing operation is completed and a private key for decryption has been received. 
       FIG. 1   e  is a schematic diagram of another embodiment of the present invention. The media server is based upon a handheld media player  128  and the client device is based upon another handheld media player  130 . The media players  128  and  130  are connectable by a wireless communication interface  132 , which may conform to the Bluetooth type of standard (IEEE 802.11) in a preferred embodiment. A media asset such as a song being played by the player  128  may be encrypted and be transmitted to the media player  130 . After receiving the song in the compressed format such as the MP3, the metadata of the song is displayed on a display screen of the media player  130 . The user of  130  may decide to purchase the asset or to abandon the asset. The completion of the purchasing process may lead to the decryption and storage of the asset for further usage. The inventive concept can readily be extended to multiple handheld media players forming an ad hoc wireless network. 
       FIG. 1   f  is a schematic diagram of another embodiment of the present invention. The media server is based upon an advertisement panel  134 . An advertisement panel may be a computing and communication device which displays advertisement contents. A data compression and encryption unit  135  may be integrated with the panel  134 . The client device is based upon a handheld media player  136 . When a user carrying the media player (i.e. a MP4 player)  136  is approaching the panel  134 , a wireless communication link is established between the panel  134  and the player  136 . The wireless communication interface  138  may conform to the Bluetooth type of standard (IEEE 802.11) in a preferred embodiment. A programming being played by the panel may be compressed and transmitted over the link or a network. A user carrying the player  136  may decide to receive the video file for the programming and to store the file in its file storage system of the player  136 . 
       FIG. 1   g  is a schematic diagram of yet another embodiment of the present invention. The media server is a theater audio/video system  140 . The system  140  includes a data storage system  142  for storing movie contents, a data processing unit  144  and an image projection unit  146 . It further includes a data compression and encryption unit  148 . The client device is a handheld media player  150  carried by an audience. The system  140  and the media player  150  are connectable by a broadband wireless communication interface such as a WiFi (IEEE 802.11b or 802.11g) network  152 . When the audience is watching a movie, the video/audio data is compressed to MP4 in a preferred embodiment and the data packets in an encrypted format based on the public/private key system are transmitted over the wireless network and are received by the media players of the audiences. The audiences have a compressed movie in its media player after watching the movie. The data, however, is encrypted. If the user decides to purchase the asset, the asset is decrypted after receiving the private key and is stored in the media player for further usage. The movie content may be divided into multiple sections and an audience may select one or many sections to purchase. 
       FIG. 1   h  is a schematic diagram of yet another embodiment of the present invention. The media server is a concert media system  153 , which comprises an audio/video recording unit  154 , an A/D converter  156 , a data compression unit  158  and a data encryption unit  160 . The compressed and encrypted media data file representing a live performance is transmitted to handheld media players  164  carried by audiences via the wireless communication device  162 . The wireless communication interface  166  between the concert media system  153  and the handheld media player  164  may be a wireless broadband communication network such as a WiFi (IEEE 802.11b or IEEE 802.11g) wireless network. The network is an ad hoc network. The media assets in a desired compressed format such as MP4 produced during the concert are transmitted to the handheld media players  164  in a real time base. The asset is encrypted based on a public/private key system. The audiences may purchase the asset through an on-line facility. Alternatively, the assets may be paid via the entry tickets and the data transmitted is not encrypted and the users may enjoy the compressed assets stored in his or her handheld media player after the concert. 
     The HiFi system and handheld media player based media delivery system is used herein as an exemplary case to illustrate the inventive concept in detail.  FIG. 2  is a schematic functional block of a HiFi audio system  200  used as the media server. The HiFi audio system  200  includes a processor  202  that pertains to a microprocessor or a controller for controlling the overall operation of the system. The audio system  200  includes a compact disk driver  204 , which reads out the media asset such as a song or a music clip from the compact disk and converts the assets into digital signals. The audio system  200  stores the digital signals in a cache  206 . The cache  206  is, for example, Random-Access Memory (RAM) provided by semiconductor memory. 
     The audio system  200  also includes a user input device  208  that allows a user to interact with the system. The user input device  208  may be a remote control, which is connected to the media player via an optical or a wireless link as well known in the art. Still further, the audio system  200  includes a display  210  (screen display) that can be controlled by the processor  202  to display information to the user. 
     When a user desires to have the HiFi system  200  to play a particular media asset such a song from a loaded compact disk, the user can select one of the available media assets by using of the remote control  208 . The processor  202 , upon receiving a selection of a particular media asset, supplies the media data (e.g., audio file) for the particular media item to a coder/decoder (CODEC)  212 . The CODEC  212  then produces analog output signals for a high precision power amplifier  214  and speakers  216 . 
     A data bus  217  can facilitate data transfer between at least the file system  204 , the cache  206 , the processor  202 , and the CODEC  212 . The HiFi system  200  is powered by a power supply  220  through power management circuits  218 . 
     According to one implementation of the present invention, the HiFi system  200  further includes a data compression unit  222  and a data encryption unit  224 . When an uncompressed media asset is being played, the asset is compressed to a desired format such as MP3. The compressed audio data is then encrypted based on the public/private key system if the user does not own the digital right. The encrypted audio asset is transmitted wirelessly via a transceiver  226 . The operation of the transceiver  226  is controlled by the processor  202 . 
       FIG. 3  shows a schematic functional block of a conventional handheld media player  300  as the client device with an integrated wireless communication capability. The media player  300  includes a processor  302  that pertains to a microprocessor or a controller for controlling the overall operation of the media player. The media player  300  stores media data pertaining to media assets in a file system  304  and a cache  306 . The file system  304  is, typically, a flash memory or a plurality of flash memories or a storage disk or a plurality of disks. The file system  304  typically provides high capacity storage capability for the media player  300 . However, since the access speed to the file system  304  is relatively slow, the media player  300  can also include a cache  306 . The cache  306  is, for example, Random-Access Memory (RAM) provided by semiconductor memory. The relative access time to the cache  306  is substantially shorter than for the file system  304 . However, the cache  306  does not have the large storage capacity of the file system  304 . Further, the file system  304 , when active, consumes more power than does the cache  306 . The power consumption is particularly important when the media player  300  is a handheld media player that is powered by a battery  320  through power management circuits  318 . The media player  300  may also include a RAM and a Read-Only Memory (ROM), which is not shown in the diagram. The ROM can store programs, utilities or processes to be executed in a non-volatile manner. The RAM provides volatile data storage, such as for the cache  306 . 
     The media player  300  also includes a user input device  308  that allows a user of the media player  300  to interact with the player. For example, the user input device  308  can take a variety of forms, such as a button, keypad, dial, etc. Still further, the media player  300  includes a display  310  (screen display) that can be controlled by the processor  302  to display information to the user. 
     The media player  300  serves to store many media assets (e.g., songs) in the file system  304 . When a user desires to have the media player play a particular media asset, a list of available media assets is displayed on the display  310 . Then, using the user input device  308 , a user can select one of the available media assets. The processor  302 , upon receiving a selection of a particular media item, supplies the media data (e.g., audio file) for the particular media asset to a coder/decoder (CODEC)  312 . The CODEC  312  then produces analog output signals for speakers  314 . A data bus  315  can facilitate data transfer between at least the file system  304 , the cache  306 , the processor  302 , and the CODEC  312 . The media player  300  also includes a bus interface  316  that couples to a data link (not shown). The data link allows the media player  300  to couple to a host computer. The media player  300  is powered by a power supply  320  through power management circuits  318 . 
     The media player  300  further includes wireless transceiver  322  for receiving the encrypted and compressed media assets. A decoder  324  is used to decode the received media file. A decryption unit  326  is used to decrypt the decoded data. The decryption unit  326  may not be necessary a piece of hardware and it may be software package controlled by the processor  302  or it may be a combination of the software and hardware implementation. A software module is used to display the metadata of the received asset on the screen of the media player  300 . A purchasing option is further displayed on the display  310  of the media player  300 . The user&#39;s selection of the purchasing of the asset will lead to the media player  300  receiving a decryption key (private key) from an on-line merchandiser to decrypt the data and to store the asset in the file storage system  304  of the media player. 
       FIG. 4  shows a representative handheld media player  400  as a media client device. The display screen  402  of the device illustrates that the metadata  404  of the compressed media asset is displayed and an option of purchase is offered to the user by selecting a “yes” or “no” according to one implementation of the present invention. If the display is a touch-screen type of device, the user may use his or her fingers or a stylus to make the selection. Alternatively, the user may move the cursor to locate the selection and actuate the selection button or pad accordingly. The media player has a user interface  406  which may be a rotational user interface as used in some of iPods from Apple and a wireless communication network interface  408  is also shown in the figure. 
       FIG. 5  shows a flow diagram of a process  500  that a media asset is transmitted from a media server  102  to the media client device  104  as shown in  FIG. 1   a . The process is characterized by that a media asset in an uncompressed format is being played by the media server  102  while the asset is being compressed, encrypted and transmitted wirelessly to the media client device  104 . The process  500  begins with a step  502  that a media asset is selected from a media category for playing in the media server  102 . Step  504  determines if the data for the media asset has been compressed to a desired format. If the step  504  decides that the data has not been compressed, the data for the media asset is compressed in step  506 . The compressed data is encrypted based on the public/private key system in one implementation in step  508 . The media server  102  receives a public key for the encryption. The data is processed and transmit wirelessly through the wireless interface in step  510 . 
     There are different embodiments with regard to the transmitting of compressed asset to the client devices  104  in the present invention. According to one implementation, the compressed asset is transmitted only one time over the wireless link  106  in a playback cycle of the asset. According to another implementation, the compressed asset may be transmitted repeatedly until the playback cycle is completed. The media server  102  may be connected to multiple media client devices  104  via an ad hoc wireless network. A client device joining the network in a later time in comparison to other peer client devices may still receive the compressed media asset as long as the playback cycle is not completed. 
       FIG. 6  shows a flow diagram of a process  600  that a compressed media asset is transmitted repeatedly when the uncompressed asset is being played by the media server  102 . The process  600  begins with a step  602  that a media asset is selected from a media category for playing in the media server  102 . Step  604  checks if the data representing the asset has been compressed to the desired format. If it has not been done, the compression is carried out in step  606 . The compressed asset is encrypted (i.e. with a public key) in step  608 . The encrypted asset is then transmitted via the wireless interface  106  in step  610 . In step  612 , the server  102  checks if the playback operation has been completed. The compressed and encrypted asset will be transmitted repeatedly until the playback operation is completed. 
     In yet another implementation, the media asset in compressed and compressed format may be divided into multiple data packets. As shown in  FIG. 7   a , each packet in compressed format corresponds to a packet in the uncompressed format. The data packets in the compressed format may be transmitted in sequential and in synchronization with the uncompressed data packets being played. The processor from the server monitors the progress of the playback operation. When a new data packet is played, a signal is sent to the processor. The processor initiates the operation of transmitting the corresponded data packet in the compressed form. Such an implementation may be useful for a long media asset such as long video programming. 
       FIG. 7   b  shows a flow diagram of a process  700  that a compressed media asset is transmitted based on data packets in synchronization with the media asset being played by the media server  102 . The process  700  begins with a step  702  that a media asset is selected from a media category for playing in the media server  102 . The format of the asset is checked in step  704 . If it has not been compressed to a desired format, it will be compressed in step  706 . The compressed and uncompressed asset is divided into multiple data packets in step  708 . The compressed data packets are encrypted in step  710 . The compressed packets are transmitted sequentially in step  712 . The transmission of the packets is in synchronization with the asset being played. If for example a song is divided into the multiple packets, a specific packet is transmitted only if a corresponded uncompressed packet is being played by the media server  102 . The compressed media asset may have been encrypted based on the public/private key system. 
       FIG. 8  shows a flow diagram of a process  800  that a compressed and encrypted media asset transmitted from the media server  102  is received by the media client device  104 . The process  800  begins with a step  802  that a broadcasted media asset is received by a user in a conventional sense. For example, a user may hear a song being played by a HiFi audio system or a user may watch a video programming being shown on the TV terminal of a digital TV. The user may be intrigued by the content. The user then switches on a receiving function of the client device  104  in step  804 . The client device is a handheld media player in one embodiment. The handheld media player receives the compressed asset in step  806  and displays the metadata of the asset on the display screen of the player. The metadata may include the author, the artist and the style of the asset. A purchase option with purchasing information may also be displayed on the screen of the player. The specific implementation has been illustrated in  FIG. 4 . If the handheld media player has been connected to the Internet, the user may carry out an on-line purchase immediately after he or she decides to purchase the asset in step  808 . If the user decides not to purchase the asset, the received data is erased in step  810  and the displayed messages are also removed from the screen. If the user selects to purchase the asset, the data is then decrypted and is stored in the file system of the client device  104  for the further usages. If the media player has not been connected to the Internet, the received asset may be stored in the file storage system in the encrypted form. The user may purchase the asset when next time the player is connected to the Internet directly or via a server such as a personal computer. 
       FIG. 9  is a flow diagram of the payment process  900  of a client device  104  after receiving a media asset from a media server  102 . The process  900  begins with a step  902  that the client device  104  receives a media asset in the compressed format. The processor in the client device  104  checks in step  904  if the data is encrypted. If the data is not encrypted, the processor controls an operation to store the received asset into its file storage system in step  906 . Otherwise, the processor checks if an on-line payment facility is available in step  908 . If the on-line payment facility is not available, the processor controls an operation in step  910  that the encrypted asset is stored and the payment is going to be carried out when the client device is connected on-line next time and when the payment facility is available. The client device  104  completes the payment via on-line facility in step  912  if the on-line payment facility is indeed available. A private key is downloaded in step  914  from the on-line merchandiser to decrypt the encrypted data. The decrypted data is then stored in the file storage system under the control of the processor. 
       FIG. 10  shows a flow diagram of the operation of an embodiment of the present invention, wherein the media server is a concert media system  153  and the media client devices are handheld media players  164  as depicted in  FIG. 1   h . The system enables a performance is recorded and broadcasted to audiences of the concert. The audiences carrying handheld media players are able to receive the performance on real time base and store the asset in their handheld media players. The process  1000  begins with a step  1002  that a performance is recorded into a digital media such as a hard disk driver or a semiconductor flash memory. The asset is compressed to a desired format in step  1004 . For example, a multi-media file is compressed to MP4 format. In step  1006 , the compressed asset may be encrypted based on a public/private key system in a preferred embodiment. The step is optional. In step  1008 , the compressed media asset is transmitted via the ad hoc wireless network formed by the concert media system  153  and the handheld media players  164 . In step  1010 , the handheld media players  164  receive the media asset. The asset may be decrypted (optional if it has been encrypted) and be stored in the file storage systems of the media player  164 . The present embodiment allows the audiences of the concert receive a digital form of performance in their handheld media players for future usages. 
     While the invention has been disclosed with respect to a limited number of embodiments, numerous modifications and variations will be appreciated by those skilled in the art. It is intended that all such variations and modifications fall within the scope of the following claims: