[FFmpeg-devel] Multichannel Vorbis encode

Justin Ruggles justin.ruggles
Tue Jan 26 23:40:41 CET 2010

Lucas Clemente Vella wrote:

> There is some time now that I reported this issue on the bugtracker:
> https://roundup.ffmpeg.org/roundup/ffmpeg/issue1325
> And this guy, jbr, kindly created a patch that solved the problem. What
> is needed now for the patch to be included in the SVN?

If you want to work on it, just update it to the latest Vorbis spec and
send it here.

> About his patch, there is a remap table that maps the channel order from
> SMPTE order to Vorbis order. What is this SMPTE order? Vorbis
> specification was updated to include channel order for 6.1 and 7.1
> audio, but I can't update the patch to include them because I don't know
> what is this SMPTE order.

I guess I just call it that because I don't like to say "Microsoft WAVE"
channel order.  I'm referring to SMPTE 428M, which is a standard for
digital cinema channel mapping.  They're essentially the same thing.
This is the channel order used internally by FFmpeg.  So decoder output
should have the channels in this order, and encoders should expect input
with channels in this order.

You can refer to the channel definitions in avcodec.h to know what the
order of channels will be in the input to the encoder.


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