HDMI with more than 2ch ?

HDMI with more than 2ch ?

[Xavier Bestel]

Hi,

I'm using HDMI output on an HD 2600, using KMS from kernel 2.6.37:
http://www.alsa-project.org/db/?f=b3f67a0890f9878b7b3f345578e24eda0aaa59ac
The problem is that only 2ch are supported (not 1, not 3 or more). I
tested with speaker-test, it only works with -c 2.

So how can I access the other PCM channels ? There are 8 of them
available in the HDMI standard, I thought the card should be able to
drive all of them.

Thanks,
	Xav

Re: HDMI with more than 2ch ?

[Xavier Bestel]

On Mon, 2011-01-24 at 10:16 +0100, Xavier Bestel wrote:
> Hi,
> 
> I'm using HDMI output on an HD 2600, using KMS from kernel 2.6.37:
> http://www.alsa-project.org/db/?f=b3f67a0890f9878b7b3f345578e24eda0aaa59ac
> The problem is that only 2ch are supported (not 1, not 3 or more). I
> tested with speaker-test, it only works with -c 2.

Just in case:
[root@awak:~]$ speaker-test -Dhw:1,3 -c6 -twav

speaker-test 1.0.23

Playback device is hw:1,3
Stream parameters are 48000Hz, S16_LE, 6 channels
WAV file(s)
Channels count (6) not available for playbacks: Argument invalide
Setting of hwparams failed: Argument invalide

Re: HDMI with more than 2ch ?

[David Henningsson]

On 2011-01-24 10:16, Xavier Bestel wrote:
> Hi,
>
> I'm using HDMI output on an HD 2600, using KMS from kernel 2.6.37:
> http://www.alsa-project.org/db/?f=b3f67a0890f9878b7b3f345578e24eda0aaa59ac
> The problem is that only 2ch are supported (not 1, not 3 or more). I
> tested with speaker-test, it only works with -c 2.
>
> So how can I access the other PCM channels ? There are 8 of them
> available in the HDMI standard, I thought the card should be able to
> drive all of them.

According to your HDMI codec it only supports stereo output, not 
8-channel PCM. This is a limitation in your hardware, not in the HDMI 
standard.

That is, if you want more channels, you probably want to ac3-encode the 
audio data.

-- 
David Henningsson, Canonical Ltd.
http://launchpad.net/~diwic

Re: HDMI with more than 2ch ?

[Xavier Bestel]

Le mardi 25 janvier 2011 à 02:17 +0100, David Henningsson a écrit :
> According to your HDMI codec it only supports stereo output, not 
> 8-channel PCM. This is a limitation in your hardware, not in the HDMI 
> standard.
> 
> That is, if you want more channels, you probably want to ac3-encode the 
> audio data. 

I've found it's a driver problem. Please read the thread titled "ALSA
multichannel through HDMI" for the gory details.

	Xav

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