[FFmpeg-user] A/V sync problems with h264/aac video fragment

Konrad Karl kk_konrad at gmx.at
Mon Apr 16 16:32:26 CEST 2012

On Mon, Apr 16, 2012 at 02:52:04PM +0100, Tom Evans wrote:
> On Mon, Apr 16, 2012 at 1:03 PM, Konrad Karl <kk_konrad at gmx.at> wrote:
>> ...
> > In case your card is able to keep up you might try -speed 1.2 or
> > similar to get a feeling about the remaining margin.
> >
> I'm not at home, in front of the screen, but it seems to play fine
> with speed 1. The maximum A-V in this case is a little high, at most
> 0.148.
> If I lower the speed to 0.8, the max A-V is much more acceptable, 0.078.

Interesting. Tried also a GeForce 550 and it was  about same speed as
the 450. After a short initial A/V desync of 10..100 ms the A/V offset
stays very close to 0 but during the elephant scene it goes up to ~1.4 sec.

(very close meaning that almost only the millisecond digit changes)

If you read this thread from the beginning I also mentioned that
the WD TV Live with its Sigma SMP8655 SoC (according to Wikipedia) is 
also not able to catch up at this scene.

In the meantime I have re-rendered this part of the movie using two pass
option in kdenlive (all other settings are same) and now the WD TV Live
is able to play w/o problems but mplayer + GeForce 450 is still to slow
but not at the elphant scene but about one minute later (not included in
the sample file).... grrr.. I yet have to learn and try to understand the
x264 options and how they affect the amount of work for the decoder.

Is there someting like a H264 disassembler available?

The elephant scene has not that much movement detail and I really 
want to know what exactly is generating so much work at the decoder.


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