[alsa-devel] Wrong channel order with multichannel HDMI on NVIDIA MCP7A

Takashi Iwai tiwai at suse.de
Tue Aug 3 22:52:21 CEST 2010

At Tue, 3 Aug 2010 13:15:28 -0700,
pl bossart wrote:
> > 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.

But if the hardware is capable of channel-remapping (the intel hdmi
code actually does even now), it's better as it works without any
software-side channel swaps.  Ditto for analog surrounds.

Of course, setting the channel-map is optional.  The first step is
to provide the API to get the map.


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