On Fri, 14.08.09 12:36, David Robillard ([email protected]) wrote: > Is there any existing 'standard' for the order of channels for > higher-than-stereo multi-channel streams?
> For example, for discrete non-interleaved 5.1 (using a full channel for > the .1) we have 6 channels: left, center, right, rear left, rear right, > LFE (see http://lv2plug.in/ns/dev/port-groups#FivePointOneGroup) > > What order should these be passed in? Any existing practices? Microsoft WAVEX and Apple CAF encode the channel mappings in a bitmap that doesn't limit you much in which channels you pick, but it does imply a specific order: http://developer.apple.com/documentation/MusicAudio/Reference/CAFSpec/CAF_spec/CAF_spec.html#//apple_ref/doc/uid/TP40001862-CH210-BCGCIJCF http://www.microsoft.com/whdc/device/audio/multichaud.mspx#EKLAC Look for kCAFChannelBit_xxx resp. SPEAKER_xxx. The CAF wand WAVEX channel mask is identical, however they used different names for the same channels. (CAF allows more flexible definitions via a different chunk, too though, which enables ambisonics). Given that both MS and Apple seem to follow this rule it might be a good idea to follow it too. And finally, RFC3551/AIFF-C (see section 4.1 of the RFC) defines an implicit channel mapping based on the number of channels. In some cases it might make sense to follow that rule. Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net http://0pointer.net/lennart/ GnuPG 0x1A015CC4 _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/mailman/listinfo/linux-audio-dev
