At Fri, 13 Feb 2009 09:28:22 -0800,
Shane W wrote:
>
> On Thu, Feb 12, 2009 at 12:41:11PM +0800, Wu Fengguang wrote:
> > static const char *channel_name[MAX_CHANNELS] = {
> > /* 0 */ N_("Front Left"),
> > /* 1 */ N_("Front Right"),
> > /* 2 */ N_("Rear Left"),
> > /* 3 */ N_("Rear Right"),
> > /* 4 */ N_("Center"), /* wav file is "Front Center.wav" */
> > /* 5 */ N_("LFE"), /* wav file is "Rear Center.wav" */
> > /* 6 */ N_("Side Left"),
> > /* 7 */ N_("Side Right"),
> >
> > Whereas the HDMI channel mapping selected for 6-channel playback is
> >
> > { .ca_index = 0x0b, .speakers = { 0, 0, RR, RL, FC, LFE, FR, FL } },
> >
> > Here the two mappings disagree on channels other than Front Left/Right.
> >
> > In theory the channel mapping should be adjusted via AC_VERB_SET_HDMI_CHAN_SLOT.
> > However I found that verb takes no effect for G35/G45. So I'm afraid
> > there's no trivial ways we can adjust the channel mapping.
>
> If the driver can't reorder the channels to what ALSA
> needs, is it possible to do it somewhere else like
> HDA-Intel.conf and use the routing plugin somehow to
> reorder things. Say for plughw:0,3 or modify the
> surround51 device?
>
> I don't know much about this interface but it looks like
> channel routing is possible here.
Well, it's a good question. Right now, surround51 is used for the
analog output which usually has the "right" ALSA channel mapping. So,
we need to detect and switch the mapping using a plugin on the fly,
and that's not so trivial.
Besides, the problem arises when both analog 5.1 and HDMI 5.1 are
implemented in the same "card". Since a "card" is defined by a
controller, not by a codec as now, one card may have both 5.1
outputs.
We might need to switch to a codec-based card approach sometime later,
but I've postponed it simply because it can break so easily the
compatibility with older versions...
Anyway, the channel mapping issue is a missing piece. There are a few
more issues, some to be implemented and some to be improved and fixed.
Takashi
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