[mythtv-users] Strange experience setting up surround sound on 0.26-fixes

[Jean-Yves Avenard]

On Tuesday, 17 September 2013, Martin Bene wrote:

>  Hi,****
>
> ** **
>
> I’m trying to get surround sound working with myth 0.26 fixes using a
> pioneer VX 1122k sound receiver; connection myth è receiver is via HDMI
> (myth graphics is NVidia ion on an Acer Aspire Revo 3610).****
>
> ** **
>
> Speakers connected to the receiver are a basic 5.1 configuration. ****
>
> ** **
>
> Checking the speaker configuration in the receiver setup/diagnostics works
> OK, i.e. the sound comes from the correct speaker when playing test sounds.
> ****
>
> ** **
>
> Now I’ve tried two configurations in myth:****
>
> ** **
>
> **a)      **Digital pass-through: works as expected, sound comes from the
> correct speakers****
>
> **b)      **Activate software mixer and 5.1 speaker configuration in
> myth: if I go into the audio test screen, I get mixed up channels:****
>
> Front Left: OK****
>
> Front Right: OK****
>
> Center: Not OK, plays on surround left****
>
> Surround Left: Not OK, plays on center****
>
> Surround Right: OK****
>
> LFE: Not OK, also plays on Surround Right****
>
> ** **
>
> Any idea how this can happen? Or even better: is there a way to configure
> channel mapping in myth so I end up with a working software mixer for 5.1?
> from a quality POV using pass-through is probably better, but the
> convenience of being able to control basic volume using the myth remote
> isn’t to be sneered at either.****
>
>
> **
>

There's a hardware bug on ion1/9400 video adapter, the mapping of channels
is incorrect. The easiest way to get around it is to force AC3 output
(setup -> audio -> advanced -> check stereo PCM). This comes with a slight
audio quality loss.
Or you'll have to adjust alsa config and remap channels there, there are
examples on how to do so on the alsa web site.
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