add basic pulseaudio support

[lrusak]

This is a resurrection of some work I did 4 years ago. I always wanted to implement some sort of pavucontrol in Kodi and this is an initial implementation of that.

Features:

• allows changing a card profile
• allows changing the default audio device

Pretty awesome that this can be done with 0 deletions 😮

Some screenshots:

[lrusak]

I've adjusted this a little bit so we now list sinks instead of cards, this will be more useful in the future.

I've also changed the layout a little bit which looks nicer (IMO)

[flubshi]

Works on pi 4 with BT headphones :)

But sound is delayed and has dropouts. Maybe this is addressed in your realtime PR for LE?

[lrusak]

Works on pi 4 with BT headphones :)

But sound is delayed and has dropouts. Maybe this is addressed in your realtime PR for LE?

pulseaudio may have to resample depending on the content and the default resample method may be too heavy. It might be worth testing different resample methods.

EDIT:
you can check by running pulseaudio with -vvv (use systemctl edit --full pulseaudio to adjust)

Mar 13 12:21:52 LibreELEC pulseaudio[904]: D: [pulseaudio] resampler.c: Resampler:
Mar 13 12:21:52 LibreELEC pulseaudio[904]: D: [pulseaudio] resampler.c:   rate 48000 -> 44100 (method speex-float-1)
Mar 13 12:21:52 LibreELEC pulseaudio[904]: D: [pulseaudio] resampler.c:   format float32le -> s16le (intermediate float32le)
Mar 13 12:21:52 LibreELEC pulseaudio[904]: D: [pulseaudio] resampler.c:   channels 2 -> 2 (resampling 2)
Mar 13 12:21:52 LibreELEC pulseaudio[904]: I: [pulseaudio] speex.c: Choosing speex quality setting 1.

You can choose different resample methods with the following:

# pulseaudio --dump-resample-methods
trivial
speex-float-0
speex-float-1
speex-float-2
speex-float-3
speex-float-4
speex-float-5
speex-float-6
speex-float-7
speex-float-8
speex-float-9
speex-float-10
speex-fixed-0
speex-fixed-1
speex-fixed-2
speex-fixed-3
speex-fixed-4
speex-fixed-5
speex-fixed-6
speex-fixed-7
speex-fixed-8
speex-fixed-9
speex-fixed-10
ffmpeg
auto
copy
peaks
soxr-mq
soxr-hq
soxr-vhq

and

echo "resample-method = soxr-vhq" > /storage/.config/pulse-daemon.conf.d/custom.conf

Then restart pulseaudio and restart kodi (kodi doesn't like when pulse is pulled out from under). Or just reboot.

Mar 13 12:27:24 LibreELEC pulseaudio[1017]: D: [pulseaudio] resampler.c: Resampler:
Mar 13 12:27:24 LibreELEC pulseaudio[1017]: D: [pulseaudio] resampler.c:   rate 48000 -> 44100 (method soxr-vhq)
Mar 13 12:27:24 LibreELEC pulseaudio[1017]: D: [pulseaudio] resampler.c:   format float32le -> s16le (intermediate float32le)
Mar 13 12:27:24 LibreELEC pulseaudio[1017]: D: [pulseaudio] resampler.c:   channels 2 -> 2 (resampling 2)

It looks like the default is speex-float-1 which shouldn't be very heavy so you can also try using the option avoid-resampling = true instead but it's likely resampling will be needed.

You should also check in kodi the option for settings -> system -> audio -> output configuration, it should be set to best match or optimized and kodi will check the format of the sink.

Mar 13 12:36:19 LibreELEC pulseaudio[1106]: I: [pulseaudio] resampler.c: Forcing resampler 'copy', because of fixed, identical sample rates.
Mar 13 12:36:19 LibreELEC pulseaudio[1106]: D: [pulseaudio] resampler.c: Resampler:
Mar 13 12:36:19 LibreELEC pulseaudio[1106]: D: [pulseaudio] resampler.c:   rate 44100 -> 44100 (method copy)
Mar 13 12:36:19 LibreELEC pulseaudio[1106]: D: [pulseaudio] resampler.c:   format float32le -> s16le (intermediate s16le)
Mar 13 12:36:19 LibreELEC pulseaudio[1106]: D: [pulseaudio] resampler.c:   channels 2 -> 2 (resampling 2)

and lastly you can also try setting the following options

default-sample-format = float32le

but it's likely you may be limited by what your bluetooth device is able to use

Sink #1
        State: RUNNING
        Name: bluez_sink.A8_BE_27_19_C3_F5.a2dp_sink
        Description: Lukas's BeatsX
        Driver: module-bluez5-device.c
        Sample Specification: s16le 2ch 44100Hz

[flubshi]

Sorry for the late reply. Works pretty good now!

Thanks a lot for your awesome explanation for my slightly off-topic problem! The following did solve my dropout issue:

You should also check in kodi the option for settings -> system -> audio -> output configuration, it should be set to best match or optimized and kodi will check the format of the sink.

[romanvm]

What is the purpose if this loop? From the looks of it this block is executed once if self.dbusDevices is not empty so it can be replaced with if self.dbusDevices: condition. Or there is something I'm missing? I saw the same code in bluetooth module and wonder why it's implemented this way.

[lrusak]

I'm not really sure what the question is. The loop iterates over a list of items returned from get_sinks. Then each item can be processed and added to the gui.

Is there a better way?

[romanvm]

The thing is that this specific loop does not iterate as such. It breaks unconditionally after the first iteration. So I'm just curious if this has any specific meaning.

[lrusak]

Ah, I didn't look at the rest of the code, yes an if is probably fine here.