Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a wireless video playback system, and more particularly to a video playback system for using a source device to control playback of a video file on a wireless display. 
         [0003]    2. Description of the Prior Art 
         [0004]    Wi-Fi Displays are wireless displays that allow users to transmit video content from a source device to the Wi-Fi Display for playback. In this way a user can watch the video content on a Wi-Fi Display that is more suitable for the user&#39;s purpose than a display of the source device. For instance, suppose the user wishes to share a video from a notebook computer to a large screen television so that multiple people can comfortably watch the video on the television together. In this example, the notebook computer is the source device and the television is the Wi-Fi Display (assuming the television supports Wi-Fi Display specifications), and the source device transmits video content to the Wi-Fi Display for playback on the Wi-Fi Display. 
         [0005]    Please refer to  FIG. 1 .  FIG. 1  is a block diagram of a video playback system  10  according to the prior art. The video playback system  10  contains a source device  12  and a Wi-Fi Display  14 . Video content is transmitted from the source device  12  to the Wi-Fi Display  14  using Real-time Transport Protocol (RTP) streaming. 
         [0006]    Unfortunately, prior art methods of sharing video content from the source device  12  to the Wi-Fi Display  14  require the Wi-Fi Display  14  to act as a mirror of what is shown on a screen of the source device  12 . Because of this, numerous steps must be performed for mirroring the video content shown on the screen of the source device  12  on the Wi-Fi Display  14 . 
         [0007]    Please refer to  FIG. 2 .  FIG. 2  is a flowchart describing the prior art method of mirroring the screen of the source device  12  on the Wi-Fi Display  14 . Steps in the flowchart will be explained as follows. 
         [0008]    Step  20 : Video content to be shown on the source device  12  must first be decoded. 
         [0009]    Step  22 : The decoded data is rendered to produce the video data shown on the screen of the source device  12 . 
         [0010]    Step  24 : A screen capture process is performed for capturing the video data stored on the screen of the source device  12 . 
         [0011]    Step  26 : The captured video data is then encoded into the H.264 video format, which is necessary for compatibility with the Wi-Fi Display  14 . 
         [0012]    Step  28 : The encoded video data is multiplexed into a Moving Picture Experts Group (MPEG) transport stream format, which is also necessary for compatibility with the Wi-Fi Display  14 . 
         [0013]    Step  30 : The multiplexed video data is wirelessly transmitted to the Wi-Fi Display  14  using RTP streaming, and the video data shown on the screen of the source device  12  is mirrored on the Wi-Fi Display  14 . 
         [0014]    Unfortunately, as seen in the flowchart of  FIG. 2 , there are numerous steps that must be performed before the video content shown on the screen of the source device  12  can be mirrored on the Wi-Fi Display  14 . The video content must first be decoded and rendered for showing on the screen. Then the video content shown on the screen must be captured, encoded, and multiplexed before it is transmitted to the Wi-Fi Display  14 . In addition, users are limited to using the Wi-Fi Display  14  as a mirror of the screen of the source device  12 , and cannot show different data on the Wi-Fi Display  14  than what is being shown on the screen of the source device  12 . Moreover, the numerous steps involved for outputting video content from the source device  12  to the Wi-Fi Display  14  may lead to quality loss and degradation in video signals. Consequently, there exists a need for an improved method of outputting video content to a Wi-Fi Display. 
       SUMMARY OF THE INVENTION 
       [0015]    It is therefore one of the primary objectives of the claimed invention to provide an improved method and video system for outputting video content from a source device to a wireless display such as a Wi-Fi Display. 
         [0016]    According to an exemplary embodiment of the claimed invention, a method of using a source device to control playback of a video file on a wireless display is disclosed. The method includes determining, with the source device, that the video file conforms to Moving Picture Experts Group (MPEG) transport stream and H.264 video format standards, wherein the video file is created without capturing contents of a screen of the source device, wirelessly transmitting the video file from the source device to the wireless display, and playing the video file on the wireless display while controlling playback using the source device. 
         [0017]    According to another exemplary embodiment of the claimed invention, a video playback system includes a source device analyzing a video file and determining that the video file conforms to Moving Picture Experts Group (MPEG) transport stream and H.264 video format standards, wherein the video file is created without capturing contents of a screen of the source device, a wireless display wirelessly receiving the video file from the source device and playing the video file on the wireless display, wherein the source device controls playback of the video file on the wireless display. 
         [0018]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a block diagram of a video playback system  10  according to the prior art. 
           [0020]      FIG. 2  is a flowchart describing the prior art method of mirroring a screen of a source device on a Wi-Fi Display. 
           [0021]      FIG. 3  is a block diagram of a video playback system according to the present invention. 
           [0022]      FIG. 4  is a flowchart describing the process of first analyzing the format of the video file to be transmitted from the source device to the Wi-Fi Display. 
           [0023]      FIG. 5  is a continuation of the flowchart of  FIG. 4  showing the steps involved with transmitting the video file from the source device to the Wi-Fi Display when the format of the video file meets a first condition. 
           [0024]      FIG. 6  is a continuation of the flowchart of  FIG. 4  showing the steps involved with transmitting the video file from the source device to the Wi-Fi Display when the format of the video file meets a second condition. 
           [0025]      FIG. 7  is a continuation of the flowchart of  FIG. 4  showing the steps involved with transmitting the video file from the source device to the Wi-Fi Display when the format of the video file meets a third condition. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Please refer to  FIG. 3 .  FIG. 3  is a block diagram of a video playback system  50  according to the present invention. The video playback system  50  contains a media server  52 , a source device  54 , and a Wi-Fi Display  56 . In the present invention, the source device  54  uses the Wi-Fi Display  56  as a virtual display of the source device  54 . That is, what is shown on the Wi-Fi Display  56  does not need to mirror what is shown on the screen of the source device  54 . Instead, the source device  54  can use the Wi-Fi Display  56  as a second screen. The first screen, which is the actual screen of the source device  54 , can serve as a control interface for controlling playback of a video file on the Wi-Fi Display  56  and can also be used for other normal computing functions performed by the user of the source device  54 . The second screen, which is the Wi-Fi Display  56 , is used for playing the video file that is sent from the source device  54  to the Wi-Fi Display  56 . By eliminating the need for the Wi-Fi Display  56  to mirror what is shown on the screen of the source device  54 , the present invention provides a simpler and more flexible way to share videos on the Wi-Fi Display  56  using the source device  54 . The Wi-Fi Display  56  may be a television, a set top box, or any other device that supports the Wi-Fi Display specifications. 
         [0027]    A video file is optionally wirelessly transmitted from the media server  52  to the source device  54  using Hypertext Transfer Protocol (HTTP) streaming. Variants of HTTP streaming, such as sending the network file using DLNA (Digital Living Network Alliance) protocol standards, can also be used for sending the video file from the media server  52  to the source device  54 . Alternatively, the video file may be provided by the source device  54  itself, thereby eliminating the need for the source device  54  to receive the video file from the media server  52 . 
         [0028]    In the present invention, the source device  54  determines if the video file to be played on the Wi-Fi Display  56  is already in the proper format for the Wi-Fi Display  56 , and converts the video file if it needs converting. The Wi-Fi Display  56  can play video files that are in the H.264 video format and which have been encapsulated into the MPEG transport stream format. Video files that are not already in this format will need to be converted by the source device  54  before the video files are wirelessly transmitted from the source device  54  to the Wi-Fi Display  56  using RTP streaming. The audio format of audio contained in the video file may be an audio format standard such as AC-3, Advanced Audio Coding (AAC), or Linear pulse-code modulation (LPCM). 
         [0029]    Please refer to  FIGS. 4-7 .  FIG. 4  is a flowchart describing the process of first analyzing the format of the video file to be transmitted from the source device  54  to the Wi-Fi Display  56 .  FIG. 5  is a continuation of the flowchart of  FIG. 4  showing the steps involved with transmitting the video file from the source device  54  to the Wi-Fi Display  56  when the format of the video file meets a first condition.  FIG. 6  is a continuation of the flowchart of  FIG. 4  showing the steps involved with transmitting the video file from the source device  54  to the Wi-Fi Display  56  when the format of the video file meets a second condition.  FIG. 7  is a continuation of the flowchart of  FIG. 4  showing the steps involved with transmitting the video file from the source device  54  to the Wi-Fi Display  56  when the format of the video file meets a third condition. Steps in the flowcharts of  FIGS. 4-7  will be explained as follows. 
         [0030]    Step  100 : Start. 
         [0031]    Step  102 : Use the source device  54  to analyze the format of the video file to be played on the Wi-Fi Display  56 . The video file may already reside on the source device  54  or may be received from the media server  52  using HTTP streaming. 
         [0032]    Step  104 : Determine if the video file to be played conforms to both the MPEG transport stream video format standard and the H.264 video format standard. If this condition is satisfied, go to step  106 . If not, go to step  110 . 
         [0033]    Step  106 : Since the video file is already in the proper format for being played on the Wi-Fi Display  56 , the source device  54  can immediately start to wirelessly transmit the video file to the Wi-Fi Display  56  using RTP streaming. 
         [0034]    Step  108 : The source device  54  uses the Wi-Fi Display  56  as a virtual display for playing the video file, and the screen of the source device  54  is used to control playback of the video file as well as to perform other computing functions. After the video file is played, go to step  132 . 
         [0035]    Step  110 : Determine if the video file to be played does not conform the MPEG transport stream video format standard but does conform to the H.264 video format standard. If this condition is satisfied, go to step  112 . If not, go to step  120 . 
         [0036]    Step  112 : Demultiplex the video file into separate audio and video components. 
         [0037]    Step  114 : The demultiplexed audio and video components are multiplexed into the Moving Picture Experts Group (MPEG) transport stream format. Since the video component is already in the H.264 video format, the video component does not need to be re-encoded into the H.264 video format. The only action that is necessary is to encapsulate the audio component and the video component into the MPEG transport stream format through a simple multiplexing step to produce a multiplexed video file. 
         [0038]    Step  116 : Since the multiplexed video file is now in the proper format for being played on the Wi-Fi Display  56 , the source device  54  can immediately start to wirelessly transmit the multiplexed video file to the Wi-Fi Display  56  using RTP streaming. 
         [0039]    Step  118 : The source device  54  uses the Wi-Fi Display  56  as a virtual display for playing the multiplexed video file, and the screen of the source device  54  is used to control playback of the multiplexed video file as well as to perform other computing functions. After the multiplexed video file is played, go to step  132 . 
         [0040]    Step  120 : Determine if the video file to be played does not conform the MPEG transport stream video format standard and also does not conform to the H.264 video format standard. If this condition is satisfied, go to step  122 . If not, go to step  132 . 
         [0041]    Step  122 : Decode the video file to separate the video file into separate audio and video components and to decode the video component into video data. 
         [0042]    Step  124 : Encode the video data to encode the decoded video data into the H.264 video format. 
         [0043]    Step  126 : Multiplex the audio component and the encoded video component into the Moving Picture Experts Group (MPEG) transport stream format. The encoded video component is now in the H.264 video format, so the audio component and the encoded video component are encapsulated into the MPEG transport stream format through a multiplexing step to produce a multiplexed video file. 
         [0044]    Step  128 : Since the multiplexed video file is now in the proper format for being played on the Wi-Fi Display  56 , the source device  54  can immediately start to wirelessly transmit the multiplexed video file to the Wi-Fi Display  56  using RTP streaming. 
         [0045]    Step  130 : The source device  54  uses the Wi-Fi Display  56  as a virtual display for playing the multiplexed video file, and the screen of the source device  54  is used to control playback of the multiplexed video file as well as to perform other computing functions. 
         [0046]    Step  132 : End. 
         [0047]    As can be seen, the source device  54  needs to determine if the video file to be played on the Wi-Fi Display  56  conforms to both the MPEG transport stream video format standard and the H.264 video format standard. If the video file is not in the correct format, the source device  54  converts the video file to the correct format. Once the video file is in the correct format, the video file can be wirelessly transmitted to the Wi-Fi Display  56  using RTP streaming for video playback. 
         [0048]    Differing from the prior art method of playing video files from a source device on a Wi-Fi Display, the present invention avoids the need for the Wi-Fi Display  56  to mirror the screen of the source device  54 . Consequently, it is not necessary to execute the computationally intensive steps shown in the flowchart of  FIG. 2  in order to perform the screen capture process for sending a copy of what is shown on the screen of the source device  54  to the Wi-Fi Display  56 . Thus, there is less burden placed on the source device  54  when outputting video to the Wi-Fi Display  56  using the present invention method than there is in the prior art method. 
         [0049]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Technology Category: 5