[mythtv] [mythtv-commits] Ticket #1104: multi channel audiosupport

Janne Grunau janne-mythtv at grunau.be
Tue Nov 6 00:11:10 UTC 2007

On Tuesday 06 November 2007 00:37:01 Mark Spieth wrote:
> >
> > I had quick look at mythtv_ac3.29.patch and noticed a few things:
> >
> > -the #if MAXCHANNELSELECT in avformatdecoder is ugly and seems to
> > be unneeded
> I think it is needed. what it does is allow maxchannels generated by
> the audio decoder to be tested and used further downstream where the
> number of channels available configures the output device.
> It lets the codec do max channels that the play can cope with. this
> can be different in mythcommflag vs alsa.

Maybe I haven't looked good enough but I've seen it only once defined in 
avformatdecoder. Just for debugging the code it imho too intrusive.
> > -are the changes to libavcodec/ac3dec really necessary? if yes, can
> > you try to get them upstream?
> only change to ac3 is now in ac3_parser.c to make ac3_sync globally
> exported (remove static).

that change in the parser is ok.

> a52dec.c had extensive changes and has been removed so it doesnt
> matter anymore.

oh, I mixed it up.
a52dec.c was just renamed to liba52.c but it will probably go away 
sooner than later.
> this was mainly for channel ordering to make it the 
> same as ac3dec and dtsdec. not sure about the channel ordering in the
> new dtsdec replacement (dca?).

libdts or libdca support was removed. libavcodec has a native dca 
decoder. I have just looked briefly at it. see below

> > -you're duplicating the DTS parsing functions in libmyth
> this is true. it needs to be defined in libmyth so perhaps avf can
> use it from there.

yes, even if it feels strange to have those codec/parser related 
functions in libmyth. but the same goes for the avcodec dependency.

> there may even be code to do the same thing in 
> lavc now but after a quick look dca doesnt seem to have a sync.

yeah, I look at it too during the merge to get rid of the dts parsing in 

> funnily enough I was doing some tests on the latest patch only a
> couple of hours before you committed :-)
> also I noticed that with libfaad and libfaac enabled, things dont
> link properly for me.

I found that too and I'm fixing it now.

> also LIBA52 in this seems superfluous since a52dec is gone.

see above

> an OT question about how mpeg timestamp wrap is now handled.

I'll need sleep to answer this


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