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

[Jason Tackaberry]

On Tue, 2009-11-10 at 13:27 +0100, Michael Niedermayer wrote:
> On Mon, Nov 09, 2009 at 07:40:59PM -0500, Jason Tackaberry wrote:
> > Can a patch that implements the request_channel_layout functionality you
> > describe be submitted later, and if so, is the patch I previously
> > submitted, which changes the default 7/8 channel layout, suitable for
> > committing now?
> 
> Personally i dont mind, but maybe others have objections ...

One objection raised was that Vorbis should have the same layout as AAC,
i.e. CH_LAYOUT_7POINT1_WIDE instead of CH_LAYOUT_7POINT1.

In practice I don't think it matters, because in either case (assuming I
understand correctly) the first 6 channels are equivalent to 6 channel
content, and the new channels are the last 2 channels, so whether we
call it CH_LAYOUT_7POINT1_WIDE or CH_LAYOUT_7POINT1 it will behave the
same to the application.

But in principle, I'm having a hard time understanding the definition of
CH_LAYOUT_7POINT1_WIDE.  It defines back left/right, and front
left/right of center, as opposed to side left/right and back left/right
as in CH_LAYOUT_7POINT1.  However, at least any 8 channel content I've
worked with (from Blurays) is CH_LAYOUT_7POINT1 and not
CH_LAYOUT_7POINT1_WIDE.

It seems to me that CH_LAYOUT_7POINT1_WIDE is unique to the AAC
specification and doesn't reflect real world content so much, which is
why I picked CH_LAYOUT_7POINT1.

Jason.