Friday, October 17, 2008

RTSP Audio video Sync


Problem :
------------

 Issues in RTSP/LiveStream Audio and video sync

 RTSP video on Demand videos are playing fine. But Only Livestream audio and video

sync is not happening  Streaming server is sending RTSP as meta data channel( just for DESCRIBE,

PLAY,PAUSE and TEARDOWN commands);Streaming server will send video and audio data over the

RTP.

Analysis:
----------

 if there is any issue in audio and video sync issues in RTSP/Livestream RTSP,
it is because of the Streaming Server.

 

 rtsp streaming servers are specialized servers;They have to do audio and video

sync; In case of rtsp streaming, it is enough to render the audio and video data using the

RTP timestamp. there is no need to do audio video sync with RTCP.if we are doing RTCP

sync, that will be better;
 But For RTCP sync timestamp calculation it will takes much time because of

floating operations involved in it. So In case of low end devices such as mobile they will

not use the RTCP for sync; it is enough to do render the video and audio with RTP

timestamp;


 
Solution:
----------
 Make the Streaming server to give output as video and audio synchronized;
 
  


 

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