[linux-dvb] Re: AW: Re: VDR and DVD with pause -> noise corrupt

[Andreas Schultz <aschultz@warp10.net>]

Klaus Schmidinger wrote:
> Ralph Metzler wrote:
> 
>>Klaus Schmidinger writes:
>> > Ralph Metzler wrote:
>> > >
>> > > Klaus Schmidinger writes:
>> > >  > If the audio frames don't contain a PTS, it's no wonder they get out of sync
>> > >  > (even in normal replay video and audio gets out of sync after some time).
>> > >
>> > > They should not any longer after my last firmware syncing patch
>> > > about 10 days ago. This patch no longer was a workaround for the
>> > > "jerking picture bug", which would just sync audio/video at the start
>> > > of playback, but a complete fix. Syncing is always on now.
>> >
>> > I just replayed a DVD with the latest versions of both driver and VDR,
>> > but after a while video and audio ran out of sync (audio was about half
>> > a second early). I'm not talking about external AC3 replay, but "internal"
>> > replay of both audio and video via the DVB card (converted by the 'ac3dec'
>> > that comes with VDR).
>> >
>> > Do others also experience this, or is it just me?
>> >
>> > >  > Is there a way to have ac3dec generate the necessary PTS for the audio frames?
>> > >  > The original Dolby Digital frames that ac3dec uses to generate the "normal"
>> > >  > audio frames must, I believe, contain a PTS, don't they?
>> > >
>> > > Of course they contain the correct PTS but reinserting it would not
>> > > help because the decoder hardware does not support syncing for PCM sound.
>>
>>But you were talking about "normal replay" which I understood to mean
>>normal MPEG2 video and MPEG audio.
>>As I already wrote above, there is no syncing if using PCM. So, I am not
>>surprised that sync is lost.
>>Or does your ac3dec convert to MPEG audio? If it does, does it insert
>>the proper PTSs?
>>
>>Ralph
>>
> 
> Maybe Andreas (Schultz) or Matjaz (Thaler) can comment on this.
> I haven't looked into the ac3dec version that was provided by
> Andreas and Matjaz yet.

Klaus, could you try to increase the frame buffer size in ac3dec? It's 
in ac3.h:
#define AC3_BUFFER_SIZE (6*1024*16)

I have been using (16*1024*16) for some experiments and this solved the 
audio jitter during fast moving scences problem. Maybe, audio starts 
lagging due to lost AC3 frames, or is it to early???

Andreas





-- 
Info:
To unsubscribe send a mail to listar@linuxtv.org with "unsubscribe linux-dvb" as subject.