[FFmpeg-cvslog] r15762 - in trunk/libavcodec: audioconvert.c audioconvert.h avcodec.h utils.c

[Måns Rullgård]

Dominik 'Rathann' Mierzejewski <dominik at rangers.eu.org> writes:

> On Saturday, 01 November 2008 at 11:53, Andreas ?man wrote:
>> pross wrote:
>> > Author: pross
>> > Date: Sat Nov  1 06:03:42 2008
>> > New Revision: 15762
>> > 
>> > Log:
>> > Add audio channel layout API to libavcodec.
>> > 
>> > Modified: trunk/libavcodec/avcodec.h
>> > ==============================================================================
>> > --- trunk/libavcodec/avcodec.h	(original)
>> > +++ trunk/libavcodec/avcodec.h	Sat Nov  1 06:03:42 2008
>> > @@ -30,7 +30,7 @@
>> >  
>> > [...]
>> >  
>> > +/* Audio channel convenience macros */
>> > +#define CHANNEL_LAYOUT_MONO              (CHANNEL_FRONT_CENTER)
>> > +#define CHANNEL_LAYOUT_STEREO            (CHANNEL_FRONT_LEFT|CHANNEL_FRONT_RIGHT)
>> > +#define CHANNEL_LAYOUT_SURROUND          (CHANNEL_LAYOUT_STEREO|CHANNEL_FRONT_CENTER)
>> 
>> Shouldn't surround include some kind of rear channel(s) too?
>
> There's two-channel Dolby Surround.

You're probably thinking of Dolby Pro-Logic (what a silly name), which
is four channels down-mixed to two in a way that allows the original
four to be partially recovered.  It involves some trick using phase
differences.

I would expect anything called surround to have at least one rear
channel.  The term surround implies that there is something in
(almost) all directions, and three front channels doesn't even get
close.

-- 
M?ns Rullg?rd
mans at mansr.com