[Live-devel] Absolute seekStream - problem with timestamps

[Francisco Feijoo]

Hello Ross,

I have subclassed OnDemandServerMediaSubsession and added support for
'trick play' using absolute times. All is working fine but the client
(which is also using Live555) is receiving wrong timestamps from the server
after pause/play is triggered. Basically I follow these steps:

1 - Client connects to the server for live video - OK
2 - Pause the client (sendPauseCommand) - OK
3 - Wait for some seconds and play the client again
(sendPlayCommand("YYYYMM....")) - The frames are correct but the client
reports wrong timestamps for 1 or 2 seconds, and then shows the correct
timestamps.


Looking at the implementation of OnDemandServerMediaSubsession I see that
the other seekStream (with NPT) is changing the rtpSink presentation times
with rtpSink->resetPresentationTimes(), while the other is not. Could this
be the problem?


Here is a sample of the received frames (in the client) after the play
command (step 3). All the frames before 1378839810.868667 are correct but
the timestamps are wrong:

Received 205 new bytes of response data.
> Received a complete PLAY response:
> RTSP/1.0 200 OK
> CSeq: 7
> Date: Tue, Sep 10 2013 19:03:37 GMT
> Range: clock=20130910T210329.68Z-
> Session: 6B73948F
> RTP-Info: url=rtsp://
> 192.168.1.6:9000/2/playback/track1;seq=42948;rtptime=1877910131
>
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122886
> bytes. Presentation time: 1378839817.440850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122886
> bytes. Presentation time: 1378839817.506850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123596
> bytes. Presentation time: 1378839817.572850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123451
> bytes. Presentation time: 1378839817.638850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122796
> bytes. Presentation time: 1378839817.704850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123719
> bytes. Presentation time: 1378839817.770850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122876
> bytes. Presentation time: 1378839817.836850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122963
> bytes. Presentation time: 1378839817.902850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123406
> bytes. Presentation time: 1378839817.968850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123183
> bytes. Presentation time: 1378839818.034850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123008
> bytes. Presentation time: 1378839818.100850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123460
> bytes. Presentation time: 1378839818.166850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123108
> bytes. Presentation time: 1378839818.232850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123045
> bytes. Presentation time: 1378839818.298850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123708
> bytes. Presentation time: 1378839818.364850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123219
> bytes. Presentation time: 1378839818.430850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123228
> bytes. Presentation time: 1378839818.496850
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123398
> bytes. Presentation time: 1378839810.868667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122975
> bytes. Presentation time: 1378839810.934667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123151
> bytes. Presentation time: 1378839811.000667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123915
> bytes. Presentation time: 1378839811.066667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122808
> bytes. Presentation time: 1378839811.132667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123383
> bytes. Presentation time: 1378839811.198667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123518
> bytes. Presentation time: 1378839811.264667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 122613
> bytes. Presentation time: 1378839811.330667
> Stream "rtsp://192.168.1.6:9000/2/playback/"; video/JPEG: Received 123482
> bytes. Presentation time: 1378839811.396667



Thanks in advance.
-- 
Francisco Feijoo
Software Engineer
EyeLynx Limited

T: +44 020 8133 9388
E: francisco at eyelynx.com
W: www.eyelynx.com
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