MP4: Synchronization and GUI

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MP4 Synchronization and GUI

• Short Tutorial
• 4/14/2008

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Outline

• Scenarios
• Media synchronization
• Graphical user interface

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Scenario A
audio1 file video1 file
Server 1
Proxy
Client 1
Server 2
PLAY audio1/video1 or PLAY audio2/video2
audio2 file video2 file
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Scenario B
PLAY audio1/video1 or PLAY audio2/video2
audio1 file video1 file
Server 1
Client 1
Proxy
Server 2
Client 2
PLAY audio1/video1 or PLAY audio2/video2
audio2 file video2 file
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Media Synchronization

• Audio and video files must be able to clearly
  demonstrate synchronization
• Speeches and singing are good examples requiring
  lip synchronization
• Each audio sample or video frame should have a
  timestamp
• Audio is leading time synchronization stream
• Video (and any other stream) should be
  synchronized with respect to audio
• Recommend synchronization point each second
• Might need to speed up or slow down video
  relative to the audio

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Media Synchronization
Synchronization Points
audio stream 3 samples/sec
0
1
2
3
4
5
6
7
8
9
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12
13
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15
16
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video stream 2 frames/sec
0
1
2
3
4
5
6
7
8
9
10
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audio 3 video 2
audio 6 video 4
audio 9 video 6
audio 12 video 8
audio 15 video 10
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Media Synchronization
Synchronization Points
audio stream 3 samples/sec
0
1
2
3
4
5
6
7
8
9
10
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12
13
14
15
16
17
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video stream 2 frames/sec
0
1
2
3
4
5
7
8
9
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audio 3 video 2
audio 6 video 4
audio 9 video 5
audio 12 video 8
audio 15 video 10
DROPPED VIDEO FRAME 6 TO CATCH UP
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Graphical User Interface

• Requires creativity
• Groups are free to use their own original design
• Should support many operations common to
  video-on-demand services
• Should display meta-data
• Proxy address and port
• Audio/video characteristics
• Sample rate
• Frame rate

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GUI Operations

• MENU
• List all of the available A/V streams
• Might use to implement channel switching
• PLAY
• Play the selected A/V stream
• STOP
• Stop the selected A/V stream
• PAUSE
• Pause the selected A/V stream
• Option buttons displaying channel number
• Two movie channels with buttons 1 and 2
• Better choice for easy channel switching

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Example GUI
Proxy address csil-core25 port 9090
Audio rate 24 Kbps Video rate 1 Mbps
PLAY
STOP
PAUSE
ChannelButtons
MENU
1
2
Note this is just an example, not a requirement
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Channel Switching

• Drop-down menu could display the following
  channels for selection
• Buttons could offer users shortcut

Channel 1 audio1.wav / video1.mjpg
Channel 2 audio2.wav / video2.mjpg