Re: [gentoo-user] Oss/Alsa/Pulseaudio: never-ending wars (VBox)

[n952162]

On 2020-02-19 19:49, Mick wrote:
> On Wednesday, 19 February 2020 17:32:46 GMT n952162 wrote:
>> On 2020-02-19 15:37, n952162 wrote:
>>> On 2020-02-19 10:48, Adam Carter wrote:
>>>> On Wed, Feb 19, 2020 at 8:06 PM <n952162@×××.de
>>>>
>>>> <mailto:n952162@×××.de>> wrote:
>>>>      I can't play audio from my VBox.  The host system only plays
>>>>      audio through the second sound card (1).  The VBox offers me OSS
>>>>      or the null driver.  The Alsa and pulseaudio pages  say OSS is
>>>>      "deprecated".   Is Oracle out of the picture?  I can't find the
>>>>      straight dope.
>>>>
>>>>      Do I have to convince VBox to talk to a different sound card?
>>>>
>>>> Which vbox version and what are your use flags?
>>>>
>>>> FWIW, for me;
>>>> app-emulation/virtualbox-6.1.2::gentoo was built with the following:
>>>> USE="alsa opengl opus pam pulseaudio qt5 sdk udev -debug -doc -dtrace
>>>> -headless -java -libressl -lvm -pax_kernel -python -vboxwebsrv -vnc"
>>>> ABI_X86="(64)" PYTHON_SINGLE_TARGET="python3_6 -python2_7 -python3_7
>>>> -python3_8" PYTHON_TARGETS="python2_7 python3_6 -python3_7 -python3_8"
>>>>
>>>> So i can use ALSA or pulse.
>>> Okay, that's a good tip.  I'll try those use flags - I have none set.
>>>
>>> I'm at virtualbox-5.2.32, which I just emerged in the last couple of
>>> days, using this profile:
>>>
>>>      [16]  default/linux/amd64/17.1 (stable) *
>> I added alsa and pulseaudio and it didn't help.  Then I noticed that
>> opus has something to do with the soundcard so I emerged that with -vU
>> but nothing needed to be done.
>>
>> It seems like VBox is interfacing directly with "the" sound card and
>> even working correctly (e.g. aplay some-file takes about the right
>> amount of time until it ends error-free), but unfortunately, I have 2
>> sound cards and the first doesn't work.
>>
>> Perhaps I could map the one to the other soundcard using .asoundrc?
>> Unfortunately, I can find no grammar for that file.
> Two outputs, one HDMI, the other analogue on this laptop:
>
> $ aplay -l
> **** List of PLAYBACK Hardware Devices ****
> card 0: HDMI [HDA ATI HDMI], device 3: Generic Digital [Generic Digital]
>    Subdevices: 1/1
>    Subdevice #0: subdevice #0
> card 1: Generic [HD-Audio Generic], device 0: CX20757 Analog [CX20757 Analog]
>    Subdevices: 1/1
>    Subdevice #0: subdevice #0
>
> This syntax swaps them over, so I can get sound out of the speakers:
>
> $ cat /etc/asound.conf
> #pcm_slave.slave_rate48000Hz {
> #        pcm "hw:1,0"
> ##	This is the rate the sound card does.
> ##	Any random input rates are resampled to this.
> #        rate 48000
> #}
> #pcm.rate44100Hz {
> #        type plug
> #        slave slave_rate48000Hz
> #}
>
> defaults.pcm.card 1
> defaults.pcm.device 0
> defaults.ctl.card 1
>
Perhaps coincidentally, that's almost identical to what I have on the host:

    01~>cat .asoundrc
    defaults.pcm.!card 1
    defaults.pcm.!device 0
    defaults.pcm.!ctl 1
    #pcm.!default {
    #    type hw
    #    card 1
    #}
    #ctl.!default {
    #    type hw
    #    card 1
    #}

That works fine there, but aplay in the guest vbox is silent.

But that gave me an idea - I tried deleting the host .asoundrc - but it
didn't help

Putting that .asoundrc in the guest won't work, because vbox only
reports seeing one sound card - there is no card 1 (i.e. second card).

The documentation that I could find about .asoundrc implies that you can
do things like mapping channels but I'm not succeeding with that.