(restored CC) Kirjoitit tiistai, 3. elokuuta 2010 23:40:13: > On Tue, Aug 3, 2010 at 1:32 PM, Anssi Hannula <anssi.hannula@xxxxxx> wrote: > > pl bossart kirjoitti tiistai, 3. elokuuta 2010 23:15:28: > >> > Well, this is one of my looong-standing TODOs. > >> > Originally I wanted to implement a new API to get/set the > >> > channel-mapping, mainly for HDMI. > >> > But, I've been recently too busy for other tasks (I can spend little > >> > time for ALSA), thus it's pending forever. > >> > >> You would only need an API to get the channel mapping. The HDMI sink > >> will report its speaker configuration through a CEA code (section 7.4 > >> of the spec), and if we parsed the EDID info we could present the > >> relevant channel order to user-space apps. > > > > I'm not sure I see how that will help with the problem of this thread, > > though, i.e. NVIDIA MCP7A hdmi codec apparently assuming audio being fed > > in windows channel order instead of alsa channel order. > > You can in theory specify the channel order in the InfoFrame (CA > field). If you had access to a register to program this, you would no > longer be tied to alsa or windows or whatever order. You would just > provide ALSA with the channels in the order you configured with the CA > code. The CA field is programmable, but the channel orders are predefined and no arbitrary channel formats are possible (see patch_hdmi.c or the related CEA spec). The nvhdmi MCP7x codec driver tries to specify a channel order by using the channel_id field in AC_VERB_SET_CHANNEL_STREAMID for the 4 slave digital converters, but it doesn't seem to have any effect (at least on hardware I have; confirmed by swapping the channel_ids around with no effect). -- Anssi Hannula _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
