[mythtv] Internal DVD Player multichannel support

Mark Spieth mark at dclabs.com.au
Sun Apr 30 20:26:00 UTC 2006


> I'm working up to some changes on the audio code to neaten up a few
> things which have been bothering me for a while
>
> - What do we need to do to get multichannel audio working with the
> internal DVD player?  Presumably some way to set the number of speakers
> the user has is a pre-req?  I guess that libavcodec can do the
> downmixing for us though?  I'm interested to do some work on this

I assume you are talking about my patch #1104.
AC3 and DTS both have downmixing support built in. just need to specify the 
number of channels when decoding. also supports upmixing for 2 -> 6 channel 
synthesised but not sure on this. still dont have a 6 channel system to 
listen/test with. there is no generic downmixing component in libavcodec 
though you could use liba52 or dts directly but the format is not 
interleaved. not sure why you would want to do this outside of the decode 
operation anyway.
general setup part of the patch has the number of channels the user has.
still havent found the time yet to clean up the audio bit and the 
interaction with avformatdecoder. sorry about this.
what I wanted to do was incorporate some way of the audio layer handling any 
number of source channels without being explicitly configured for them. 
output channels (analog) I thought just limit to 2 and 6 which alsa can 
handle.

cheers
mark 



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