[vlc-devel] RTP jitter buffer does not work

Marian Ďurkovič md at bts.sk
Mon Sep 7 21:53:06 CEST 2009

On Mon, 7 Sep 2009 22:37:40 +0300, Rémi Denis-Courmont wrote
> Le lundi 7 septembre 2009 22:09:49 Marian Ďurkovič, vous avez écrit :
> > Well, after the above change, we now only have 3*jitter left, i.e. 3*0.2
> > msec. Reordering happens due to variable buffering delay in multiple paths
> > (either in the network or inside the hardware), so we need much more here.
> We still wait for an extra:
>  3 * delay_variance + |delta_seq| * packetization_time.
> over the expected receival time. The packetization time factor is 
> implicit from the fact that we are waiting from the time when a LATER 
> packet was received.

Well, yes, |delta_seq| * packetization_time has already passed, but we compute
deadline from the last dequeued packet. If jitter is small, it might well happen
that the computed deadline is in the past, so we're not waiting at all:

[0x8d70560] rtp demux error: now:       4100489301007
[0x8d70560] rtp demux error: last_dq:   4100489299241
[0x8d70560] rtp demux error: deadline:  4100489300941

So we definitely need some minimal value.

    With kind regards,


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