[mythtv] [Experimental PATCH] BIG DVB PATCH V3.2 Released
James Armstrong
james at thearmstrongs.org
Mon Dec 20 15:07:52 UTC 2004
> For my case its not. Something is still wrong somewhere, I don't know
> what yet. The patch I did to mpeg.c allows me to use the software ac3
> decoder. This patch may very well be an introduced bug to cancel out a
> bug which I can't find yet.
>
> I am in Australia, where broadcasts are transmitted in the DVB format.
> For my case ip->cid is already 0xbd for AC3, 0xc0 for MPEG2 audio,
> and 0xe0 for video when CorrectStreamNumber is called (I only run it
> for a short while so I may very well be wrong here)..
>
> The original function replaces all audio with 0xc0 (hence everything
> calls the software mpeg decoder), but the patch in DVB v3.2 just sets
> ip->cid to the same original value (which is better as even if/when
> the original value is wrong, the new CorrectStreamNumber will
> hopefully set it correctly).
>
> AC3 passthru to an external AV receiver may work just by fixing up
> CorrectStreamNumber (I don't know as I don't have a AV receiver), but
> software decoding doesn't work, mythfrontend crashes on my machine at
> ScanStreams.
>
> Just found out that in ScanStreams, the line:
>
> AVCodec *codec = avcodec_find_decoder(enc->codec_id);
>
> evals to nothing as enc->codec_id = 86021 which is 0x15005 which is
> CODEC_ID_DTS. (incidently I couldn't register the DTS codec). I am
> tempted to just swap the order of CODEC_ID_DTS and CODEC_ID_AC3 in
> avcodec.h and see if it works. At the moment trying to find out where
> 0x15005 comes from.
>
> My apologies for the misconceptions in the A52/AC3 specs... :(
>
Does anyone know if this will fix the problem I have with playing back
HD recordings from ABC here? I only get audio out the front right
speaker using OSS Emu and with ALSA I get choppy/broken audio out the
same speaker. With mplayer I get good audio out all speakers. In mplayer
with debug is says it is using a codec (liba52 or something like that)
to decode the ac3 audio.
- James
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