[mythtv] Re: Software AC3 decoding when watching TV

[Juha Kuikka]

On Wed, 15 Dec 2004 17:54:24 +0800, Tj <htpc at treblid.dyndns.org> wrote:
> Following up my mails about software AC3 decoding. Found some things so far:
> 
> (1) It appears that AC3 of DVB and A52 of ASTC are one and the same
> (ac3dec.c doesn't work as there is no directory called libac3, even in
> the latest ffmpeg sources).

I think this http://liba52.sourceforge.net/ should be installed so
ffmpeg can decode ac3.

> (3) Tuned to HDTV channel. No go. AC3 has the same startcode as MPEG2,
> thus myth(or ffmpeg?) gives it the codec_id = CODEC_ID_MPEG2. Hence all
> along Myth is trying to use the MPEG2 decoder to decode AC3 streams
> (that's why I am hearing rubbish when I use a AC3 APID).

Depends. AC3 should be in privete_stream_1 PES packets in TS stream. 
At least in DVB and American ATSC.  This is where ffmpeg searches for
it, see mpegps_read_packet and mpegps_read_pes_header. What do you
mean with "startcode"?

> sound? If yes, then australia's HDTV broadcast is really messed up.

Do you have a bit of stream somewhere? I could take a look.

  - Juha
-- 
Madness takes it's toll. Please have exact change.