[FFmpeg-devel] [PATCH] 8 channel layout fix for Vorbis decoder

[Michael Niedermayer]

On Sat, Nov 07, 2009 at 11:08:26AM -0500, Justin Ruggles wrote:
> Michael Niedermayer wrote:
> 
> > On Tue, Nov 03, 2009 at 07:39:51PM -0500, Jason Tackaberry wrote:
> >> Hi,
> >>
> >> The attached patch implements sane channel layout behaviour for 7 and 8
> >> channel Vorbis files.
> >>
> >> The Vorbis specification [1] says that the layout for greater than six
> >> channels is left up to the application.  I think the most sensible and
> >> consistent layout for 7 and 8 channels is their 5 and 6 channel
> >> counterparts with back left/right channels appended.
> > 
> > ahh, xiph-alzheimer design again
> > from all options they succeed in selecting the one that is most different
> > from everyone else no matter how broken the option is even on its own
> > 
> > 
> > so what are our options
> > 1. leave channels as they are ordered
> >    -> requires each application to have a special case for vorbis because
> >       this order is never what one expects
> > 2. do a best effort reordering 
> >    -> someone will complain that its not correct for his file (that he just
> >       created)
> >       and his application could magically do better if only the evil
> >       ffmpeg didnt reorder channels
> > 
> > solution:
> > add a value to request_channel_layout that specifies raw channel order and
> > layout without any changes and then do the reorder as you do in your patch
> > if this is not requested.
> > comments? suggestions? flames?
> 
> I like it.  So value to use?
> 
> 0x80000000 already means "all layouts supported" since we're using

is that documented in the appropriate header?
btw, what does "all layouts supported" mean for request_channel_layout ?


> Microsoft's dwChannelMask values (for the low 32 bits at least).  So
> maybe 0x100000000LL or 0x8000000000000000LL?


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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