[mythtv] [PATCH] AvFmtDec scanAudioStreams

[Daniel Thor Kristjansson]

On Thu, 28 Oct 2004, J. Donavan Stanley wrote:
]By the way, can anyone point me to some specs for MPEG2 formats.  The selection
]of the audio track to use was based on a sampling of some DVD rips I had,
]however it's not right for ALL DVD rips.  I assume theres a rule to follow for
]always getting the main audio track for a given stream, I just don't know what
]it is.

I don't know about MPEG2 in general, but with ATSC there is an 
AudioStreamDescriptor either in the PMT or the TVCT that tells you if 
the service is a major or minor service. Then to select between major 
services you can look at the language code.

Unfortunately, this may not be a "full service" which means you may need 
to mix a major service with some minor services to get both the dialog 
and background sounds. (If it is a full service the descriptor tells you 
this too.)

For details look at a_52a.pdf from atsc.com, at about page 120.

DVB has a similar descriptor called an "AC-3 Descriptor" which is 
lightly described in a_52a.pdf at about page 125.

-- Daniel