At Tue, 11 Sep 2012 10:22:23 +0200, Takashi Iwai wrote: > > At Tue, 11 Sep 2012 16:10:43 +0800, > Raymond Yau wrote: > > > > 2012-9-11 ??1:43 ? "Takashi Iwai" <tiwai at suse.de> ??? > > > > > > Hi, > > > > > > does anyone have concern if I push the current channel map API patches > > > (in sound-unstable git tree topic/tlv-chmap branch) for linux-next, > > > i.e. for inclusion to 3.7 kernel? > > > > > > I don't worry too much about the kernel API. This can be refactored > > > later. But the kernel ABI must retain, so we won't change in an > > > incompatible way any longer once after it's merged to the upstream. > > > > > > So, if anyone sees a flaw in the kernel ABI definition using control > > > elements, let me know. > > > > > > (But note that the API can't be perfect for all generic purposes. > > > It's designed to be "good enough" for a big lack for multi-channel > > > streaming. Of course, this doesn't discourage to use the API for any > > > other purposes.) > > > > > > > How about the channel map of the usb mono playback device and those sound > > card which can pan mono to stereo speakers and headphone? > > If the device specifies which speaker position the mono channel is > for, then you can map it properly. Unless it's really specified by > the device, the mono stream is UNKNOWN position in general. 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. Takashi
