[FFmpeg-devel] [PATCH] write AC-3 metadata

Michael Niedermayer michaelni
Sat Jan 1 02:52:51 CET 2011


On Fri, Dec 31, 2010 at 11:53:42AM -0500, Justin Ruggles wrote:
> On 12/31/2010 10:08 AM, Anssi Hannula wrote:
> 
> > On 31.12.2010 15:31, Kieran Kunhya wrote:
> >>> clean effects ? This field indicates that the referenced
> >>> program element has no language.
> >>> hearing impaired ? This field indicates that the
> >>> referenced program element is prepared for the hearing
> >>> impaired.
> >>> visual_impaired_commentary ? This field indicates that the
> >>> referenced program element is prepared for the visually
> >>> impaired viewer.
> >>> [...]
> >>
> >> For what it's worth, I've never seen anyone use anything other
> >> than "undefined" for that field in MPEG-2 systems. Visual Impaired
> >> commentary uses the country code "NAR" over here in the UK.
> > 
> > Here in Finland visual impaired commentary is marked correctly using
> > that field (additionally it has the country code "hun").
> 
> Well, since this is both codec-level and container-level information,
> there are limited options to support it.
> 
> 1) a new field in AVCodecContext called audio_service_type

>     - define FF_AUDIO_SERVICE_TYPE_AC3_COMPLETE_MAIN, etc...
>     - define FF_AUDIO_SERVICE_TYPE_MPEG2LANG_CLEAN_EFFECTS, etc...

values have to bethe same between ac3 and mpeg2 for this to work


>     - set the values in demuxers/decoders/muxers/encoders


>     - I don't know if this would copy over when transcoding though

would require 1 line in ffmpeg.c


> 
> 2) Move the metadata API to libavcodec

that should be done anyway one day ...

[...]
--
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many that live deserve death. And some that die deserve life. Can you give
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even the very wise cannot see all ends. -- Gandalf
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