[opus] Meaning of mapping[]

Brendan Bolles brendan at fnordware.com
Mon Jan 6 10:24:46 PST 2014

Hey everyone, I've added Ogg Opus support to my Adobe Premiere plug-in here:


Now I'll add Opus support to me WebM plug-in too.  I've got this Opus stuff mostly figured out, but I have a few questions.  Here's one:

What do the numbers in mapping mean?  I see that opus.h refers to the Vorbis channel mapping order, so does mapping in Opus take that order and re-arrange it?

For example, opus_multistream_surround_encoder_create() sends out mapping[] = {0, 4, 1, 2, 3, 5}.  For 6 channels the Vorbis order is front left, center, front right, rear left, rear right, LFE.  So does this mean that Opus is asking for front left, rear right, center, front right, real left, LFE?  Seems a little odd.


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