[dvblast-devel] PATCH: Avoid jitter in RTP timestamps

[Marian Ďurkovič]

Hi Zoilo,

On Tue, 22 Sep 2009 00:37:55 +0200, Zoilo Gomez wrote
> If I stream the TV program over the network using dvblast (or vlc) , 
> then the ticker tape does not scroll smoothly anymore; however without 
> streaming it looks perfect. Therefore I assume that the streamer 
> introduces some kind of clock jitter into the ts.
> 
> Found your patch, and noticed that it has not yet been applied to the 
> main svn code, so I applied it, but alas: same result. No noticeable 
> difference; ticker tapes are still jittery.
> 
> Perhaps my problem is different, or do you have some suggestion how to 
> proceed? Do you have a test channel where I can see the difference 
> with/without patch?

  this patch addresses an issue in RTP timestamps, which according to spec
should be only used to compute jitter average. Video decoding should be based on
PCRs and timestamps inside the TS, i.e. my patch does not have any influence on
this.

  BTW, DVBlast and VLC use completely different methods when streaming - DVBlast
copies TS packets and PCRs in them from DVB input without any modifications,
while VLC recreates TS from scratch with completely different PCRs. If you're
seeing the same jittering with both, the problem might be on the client side.

  As for the ticker tapes, it's very hard to get them displayed right on a PC.
Typically, the monitor refresh rate is 60 Hz which doesn't map anyhow into the
50 Hz refresh rate of the TV system.

   With kind regards,

         M.