[pulseaudio-discuss] [PATCH] alsa-mixer: sb-omni-surround-5.1.conf: remove analog-surround-21, add Linux 4.3+ support

[Tom Yan]

What do you mean by "noise in nth output starting from 1 instead,
relatively hight frequency light clicking"? How were you testing
exactly? speaker-test? if so what're the "-D"s you used? Can you paste
full commands (and maybe even the text output).

What you said doesn't seem to make sense. If surround51 works, then
surround41 and surround20 should at most cause a signal/speaker
mismatch. I don't see how it can produce some weird noise/click.

On 16 January 2016 at 16:26, Nazar Mokrynskyi <nazar at mokrynskyi.com> wrote:
> OK, I've spent another hour or so trying different combinations and it seems
> to be a bug inside either ALSA or PulseAudio.
> SB Omni Surround 5.1, as you can see from name, has 6 outputs:
> front-left,front-right,rear-left,rear-right,front-center,lfe (lets ignore
> other non-related inputs/outputs here)
> I've done many experiments and defined which modes are working and which
> doesn't.
>
> Modes that work fine:
> - 5.1
> - 5.0
> - 4.0
> - 2.0
>
> Modes that doesn't work fine:
> - 2.1 (stereo only, noise in 3rd output starting from 1 instead, relatively
> hight frequency light clicking)
> - 4.1 (quadro only, noise in 5th output starting from 1 instead, relatively
> hight frequency light clicking)
>
> It is clearly visible that any time I want to skip some output, for
> instance:
>     ttable.0.FL 1
>     ttable.1.FR 1
>     ttable.5.LFE 1
> instead of
>     ttable.0.FL 1
>     ttable.1.FR 1
>     ttable.2.LFE 1
>
> To direct LFE to proper output it doesn't work. This is the same reason why
> 5.0 is working fine (no skipped outputs, all consequent) and 4.1 doesn't (we
> need to skip 5th output starting from 1 and use 6th instead).
>
> When I try this:
>     ttable.0.FL 1
>     ttable.2.FR 1
>     ttable.1.LFE 1
> then as expected I can hear LFE in right front output.
>
> Any hints from anyone what is wrong here? There are literally NO DOCS about
> how it works internally, so these experiments all I can provide at the
> moment.
> There were pulseaudio logs in this thread if anyone needs details.
>
> ALSA 1.1.0, PulseAudio 7.1, Ubuntu 16.04 x64
>
> Sincerely, Nazar Mokrynskyi
> github.com/nazar-pc
> Skype: nazar-pc
> Diaspora: nazarpc at diaspora.mokrynskyi.com
> Tox:
> A9D95C9AA5F7A3ED75D83D0292E22ACE84BA40E912185939414475AF28FD2B2A5C8EF5261249
>
> On 28.11.15 09:56, Raymond Yau wrote:
>
>
>>
>> I've been looking at those lines. Do you think it should be done in
>> USB-Audio, or should it be added into separate config file specific for this
>> sound card?
>
> http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=src/conf/pcm/surround21.conf;hb=HEAD
>
> The route of surround21 is hardcoded to use surround51 , this mean your
> ttable are used by those usb audio support 6 channels, those usb audio which
> only support 8 channels need to define their own 21 route as both surround51
> and surround71 of usb audio use route plugin
>
>
>
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