Re: Enable FFmpeg AC3 / DTS decoders

On ma, 2014-06-16 at 05:06 -0400, Brad Smith wrote:
> On 16/06/14 5:02 AM, Petri Hintukainen wrote:
> > Hello,
> >
> > On su, 2014-06-08 at 20:38 -0400, Brad Smith wrote:
> >> Here is a diff to enable the AC3 / DTS decoders via FFmpeg.
> >>
> >>
> >> diff -r a974f181df3f src/combined/ffmpeg/xine_audio.list
> >> --- a/src/combined/ffmpeg/xine_audio.list	Fri Jun 06 21:12:20 2014 +0200
> >> +++ b/src/combined/ffmpeg/xine_audio.list	Sun Jun 08 20:03:38 2014 -0400
> >> @@ -41,15 +41,16 @@
> >>   WAVPACK			WAVPACK			WavPack
> >>   AMR_NB			AMR_NB			AMR narrow band
> >>   AMR_WB			AMR_WB			AMR wide band
> >> +A52			AC3			AC-3
> >>   EAC3			EAC3			E-AC-3
> >>   AAC			AAC			MPEG4
> >>   AAC_LATM		AAC_LATM		AAC LATM
> >>   ADPCM_G726		ADPCM_G726		ADPCM G726
> >>   QCLP			QCELP			QualComm Purevoice
> >>   OPUS			OPUS			Opus Audio
> >> +DTS			DTS			DTS
> >>
> >>   # disabled codecs (ref. configure.ac)
> >> -!			AC3
> >>   !			ADPCM_ADX
> >>   !			ADPCM_G726
> >>   !			DSICINAUDIO
> >
> > This also changes default decoders for AC3/DTS. Priority of ff_audio
> > decoder is higher (7) than current libdts (1) / liba52 (5) decoders.
> > Maybe we should also increase those priorities ?
> >
> > I don't know if AC3/DTS passthru works with ffmpeg decoder.
> >
> > Is there some advantage in preferring ffmpeg instead of liba52/libdts ?
> > Downmixing support ? Maybe that could be moved to audio out so that all
> > decoders could benefit from it :)
> 
> For our (OpenBSD) packages we consider it advantageous to reduce the
> external dependencies.
> 
> IMO the FFmpeg decoders are also advantageous as they support for 
> example the newer DTS formats like DTS-HD HRA / MA and are also
> optimized for certain platforms using SIMD support.

Right.

The problem with xine's ffmpeg audio decoder is missing AC3/DTS passthru
support. I can easily move passthru support from a52/dts plugins to
separate plugin, but I need someone to test it. Until that I've
increased liba52/libdca priority.


- Petri


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