[vdr] softdevice audio problem. audio repacker issue?

Stefan Lucke stefan at lucke.in-berlin.de
Sun Mar 18 00:36:40 CET 2007


On Saturday 17 March 2007 20:57, Reinhard Nissl wrote:
> Hi,
> 
> Stefan Lucke wrote:
> 
> > Dumping the first 16 bytes of audio packets we get, shows the following:
> > ff fc a4 0d b6 64 88 55 33 65 56 54 44 21 33 33
> > ff fc a4 0d 54 6a 88 65 33 44 56 54 33 33 33 33
> > ff fc a4 0d 02 a4 88 55 33 54 66 44 43 33 33 33
> > 99 77 1b e6 34 b2 5f 41 e8 5b 90 a9 d2 04 24 5e
> > ff fc c4 04 7c c4 dd 44 44 66 57 55 55 55 33 33
> > ff fc c4 04 1d 61 dd 46 44 66 55 55 55 55 33 33
> > 68 6a 60 18 d8 52 92 4f 54 98 0b 93 27 22 4e 74
> > ff fc c4 04 94 01 dd 44 56 66 55 55 55 55 33 33
> > 
> > Is audio repacker active even for old recording ?
> > When I deactivate audio repacker, sound is garbled allways.
> 
> cAudioRepacker was introduced after VDR-1.3.26 and it is only active in
> transfer mode or while recording. It is not active while replaying a
> recording, so it has no influence on recordings taken with VDR-1.2.1.

Thanks for pointing that out.

So we should look for solving that issue in softdevice. Hopefully 
FF-cards are not involved in such an issue (sound, sync issues).

> 
> But when cAudioRepacker was not active, an audio PES packet may contain,
>  multiple audio frames and/or just a fragment of an audio frame at the
> beginning or at the end of the PES packet.
> 
> So if ffmpeg can only work on single and/or complete audio frames,
> you'll have to break the PES packet apart and assemble the fragments at
> the end and the beginning of the next PES packet. cAudioRepacker can do
> this for you. Just feed it PES packets via it's Repack() method and the
> given ResultBuffer will contain a PES packet per audio frame.

Some time ago I've been told from ffmpeg people, that we sould read
packets from AVParser. I guess that's the point which kicks us now.

-- 
Stefan Lucke



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