[FFmpeg-devel] [PATCH] New vorbis channel layouts

Robert Swain robert.swain
Fri Jan 29 14:55:31 CET 2010


On 27/01/10 14:41, Michael Niedermayer wrote:
> On Thu, Jan 14, 2010 at 05:17:42PM +0100, Robert Swain wrote:
>> Hello,
>>
>> New channel layouts have been added to the Vorbis spec [1] for 6.1 and 7.1
>> channels. Attached is a patch for adding such support to the FFmpeg
>> decoder.
>>
>> If you look at the spec, you should note that surround rear left/right are
>> dropped in 6.1 and surround left/right (or side left/right in FFmpeg) take
>> their place, plus surround rear centre (back centre in FFmpeg). And 7.1 is
>> just the 5.1 configuration with side left/right which appears to be the
>> standard 7.1 setup according to our definitions.
>>
>> Best regards,
>> Rob
>>
>>
>> [1] http://www.xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-800004.3.9
>
>>   vorbis.h      |    4 ++--
>>   vorbis_data.c |   10 +++++++---
>>   2 files changed, 9 insertions(+), 5 deletions(-)
>> f2b305165413310ea122f7c4fd650f903c219c5c  20100114-1713-new_vorbis_channel_configs.diff
>
> if tested&works and matches spec then ok

I had to change a couple of bits in vorbis_dec.c that I'd missed where 
there were two checks against vc->audio_channels > 6 to > 8 but other 
than that it was fine.

I tested with http://web.mit.edu/xiphmont/Public/8.ogg which is a 
semi-official (xiphmont pointed me to it) 7.1 test sample created from 
the MS ChannelID wav that we have on samples.mphq. I checked that the 
order of that matched the vorbis spec when not reordering and it does so 
all is fine.

'Applied'.

Regards,
Rob



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