> I think the problem with recording AC3 is that in
> CorrectStreamNumber() we mandle stream_id's of all audio pids to 0xC0.
> This is wrong for AC3 audio and propably breaks it.
Ah, there's the code I was looking for.... I remember seeing something like that when I searhed for AC3 in gasommer..
>> have a MUCH easier time doing subtitles as well so I am completely sold.. Sorry
>Well yes, we could save on the trickery. :)
More trickery... From the posts I realised that 0xbd is a private stream (and not AC3 as I previously thought). But If I modified transform.c and treat 0xbd as an audio stream, the function find_next_start_code will return that. Myth then detects this AC3 audio stream correctly and loads the A52 decoder. I can even change to a channel using MPEG2 stream and Myth will automatically use the MPEG2 decoder. All provided that bit_rates, frequencies, etc computes to some non zero values in get_ainfo or get_vinfo. Otherwise, backend will crash in the function ps_pes() somewhere at line 1981 (all in transform.c):
if (pv->has_vi && pv->vi.bit_rate && !pv->muxr ) (something similar to that)
pv isn't null when it crashed, memory corruption perhaps (don't think get_ainfo is meant to read 0xbd packets)? Will find out more tonight, think I must have missed something when I forced 0xbd to an audio stream.
>> if I shot from the hip earlier.. Do you have a quick patch that I could make to
>> transform.c (since its your code) to make it dump an ATSC AC3 stream? None of
>> ATSC channels ive watched have sound and I am pretty sure tranform just isn't
>> putting them in the ringbuffer since its looking for a differnet header than
>> PrivateStream..
> Please see above. I think that's the problem.
When tuning to MPEG (0xc0) audio, I find that there are some ipackets(? or something) with a code of 0xbd as well.. Although there's no apparant breakage in sound, will this be a problem?
>> The biggest issue right now is really time.. I want to get this code into
>> myth-cvs as soon as I can and doing TS recording may not fit at first.. I have
>> more than enough on my plate.. Its possible Jesper could do this, but I do not
>> set his schedule.. I know both John and I have tons of work to do before this
>> whole thing is ready..
>I can help.
So can I. Though I think I am restricted to a tester role for now as I still have no idea yet how Myth works or details about the DVB format.
OT: Turns out I am duped by the marketing hype as most programs in Australia Perth broadcasts their programs in AC3 stereo, not AC3 surround sound..
Regards.
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