[Live-devel] RTSP Seek problems

[Philippe Bridant]

>
>
>> > [...]
>
>
> No.  Once again: The "RTP timestamp" and the "presentation time" are
> (effectively) the same thing - they tell the receiver when to *render*
> the audio or video frame.  They are not supposed to have anything to do
> with any 'seeking' that may (or may not) have occurred - at the server 
> end.
>
> However, from your graphs, it seems that you are apparently using a RTSP
> server that changes the "RTP timestamp" (and thus "presentation time")
> to match the seek operations.  THIS IS WRONG!  RFC 3550, section 5.1
> specifically says that the RTP timestamp "MUST be derived from a clock
> that increased monotonically and linearly in time".
>
> It turns out, therefore that the RTSP server (the "QuickTime Streaming
> Server", aka. "Darwin Streaming Server") that you are using for your
> testing is broken.  (My copy of the "Darwin Streaming Server" also has
> the same bug.  I'm going to report this bug to Apple.)


Ok. So DSS does modify the RTP Timestamp.

I my previous mails, I told you about the timestamps which was erroneous
during only 4 seconds and then came back to normal values. It seems that
it is thanks to the RTCP synchronisation.

What would be the better thing to do ?

1) Modify DSS to have a continuous RTP Timestamp.
It'sure that DSS *MUST* provide a solution for this problem.
Will they correct it ?  Will we have to correct it our selves ?

2) Resync the PTS by having an RTCP synchro after each PLAY command.
This could be, in my opinion, a great solution to be *SURE* that
the PTS is *always* correct...


========================================================================

I have tested a playback with VLC VOD module (using LIVE.COM streaming
capabilities) to look is the RTP Timestamps did changed like DSS.

But it seems that the LIVE.COM *doest not use* the hinting track(s).

[00000235] mp4 demuxer debug: find 6 tracks
[00000235] mp4 demuxer debug: track[Id 0xc9] read 64 chunk
[00000235] mp4 demuxer debug: track[Id 0xc9] read 636 samples length:25s
[00000235] mp4 demuxer debug: adding track[Id 0xc9] video (enable)
[00000235] mp4 demuxer debug: track[Id 0x65] read 118 chunk
[00000235] mp4 demuxer debug: track[Id 0x65] read 1179 samples
[00000235] mp4 demuxer debug: adding track[Id 0x65] audio (enable)

[00000235] mp4 demuxer debug: ignoring track[Id 0x2]
[00000235] mp4 demuxer debug: ignoring track[Id 0x1]
[00000235] mp4 demuxer debug: ignoring track[Id 0x100c8]
[00000235] mp4 demuxer debug: ignoring track[Id 0x10064]


This results an impossibility to seek... Am I wrong ?

Is it possible to ask LIVE.COM to use the hinting track ? If not is it 
scheduled ?


Thanks again

-- 
Philippe BRIDANT
IT Engineer

SmartJog S.A
Phone:  +33 (0)1 4996 6319
Fax:    +33 (0)1 4996 6405
Mobile: +33 (0)6 7277 7577
philippe.bridant at smartjog.com