Re: [alsa-devel] Channel map API patches: to be 3.7 or not to be?

Takashi Iwai wrote:

BTW, this reminds me of an open question: is it useful to add SND_CHMAP_MONO, or is it just redundant?

It's nothing but indicating a mono channel without any channel position, so I supposed SND_CHMAP_UNKNOWN being sufficient. OTOH, SND_CHMAP_MONO would give a clear sign of mono streams while SND_CHMAP_UNKNOWN could be used for any other exceptional purposes.

What would it be used for?

Labeling surround channels is necessary for reordering them or for doing up/downmixing. A "mono" channel, however, does not appear to have any semantic difference from a single "unknown" channel.

Regards, Clemens