[PROBLEM] Bluetooth Audio output (Transmitter)

[ppianigiani]

Hello all,
I'm an Xbian newbie (as you might understand from the rest of my post... ) and I'm trying to use BT headphones connected to my RPi3B+ onboard BT module, running the latest version of Xbian and it seems I'm hitting permissions issues.

So far I was able to:

• connect my BT headphones to the RPi BT onboard module (using pulseaudio/bluetoothctl)
• select "ALSA: Playback/recording through the PulseAudio sound server" on Kodi's System > Audio > Audio output device config
  

When I boot up my RPi, the BT HPs always get connected and once Kodi has automatically started, I can hear beeps&ticks when moving through Kodi's menus, so everything seems to work fine, but when I try to play a video from Kodi or from an addon (i.e. Amazon VOD or YouTube), the audio stops on my BT HPs and after that, no way to get it working again (no more beeps&ticks when moving through Kodi menus).

Then, if I close Kodi and from a ssh console (logged in as xbian user) I kill the "pulseaudio" process, restart it, re-connect my BT HPs using "bluetoothctl" commands and restart kodi (using "kodi start" command), then everything works fine, I can hear perfect audio on my BT HPs when playing a video both through Kodi or through an addon.
This second scenario makes me think I'm hitting some permissions issues on the first scenario, but I was not able to find the cause: I tried to follow all the instructions in this thread, but I found no solution yet.

Here's my system config:

Software
XBian version: Xbian 1.0 (knockout) (kernel: Linux 5.4.114+)
XBMC/Kodi version: 19.1 Matrix
Overclock settings: None

Hardware
Device type and model: Raspberry Pi 3 Model B+
Power supply rating: Output 5V/2.0A
SD card size and make/type: MicroSD HC 32GB - A1
Network: Ethernet eth0 (static setting)
Connected devices (TV, USB, network storage, ...): HMDI monitor

Here's a log file when I can't hear any audio from my BT headphones when playing a video:
kodi.log from NON-working scenario

And here's a log file from the second scenario, when everything works fine, as expected:
kodi.log from working scenario

From what I've seen on the log files, in the first scenario I can see the following log entries:

Code:

2021-05-28 10:38:16.274 T:3137     INFO <general>: CActiveAESink::OpenSink - initialize sink
2021-05-28 10:38:16.274 T:3137    DEBUG <general>: CActiveAESink::OpenSink - trying to open device ALSA:default
2021-05-28 10:38:16.274 T:3137     INFO <general>: CAESinkALSA::Initialize - Attempting to open device "default"
2021-05-28 10:38:16.284 T:3137     INFO <general>: CAESinkALSA::Initialize - Opened device "default"

This seems to be when I can hear sounds from my BT headphones moving thorugh Kodi menus, but when I start playing a video, these are the entries on the log file:

Code:

2021-05-28 10:40:17.329 T:3137     INFO <general>: CActiveAESink::OpenSink - initialize sink
(...)
2021-05-28 10:40:17.536 T:3137     INFO <general>: CAESinkALSA::Initialize - Attempting to open device "default"
2021-05-28 10:40:17.547 T:3137     INFO <general>: CAESinkALSA - Unable to open device "default" for playback
2021-05-28 10:40:17.547 T:3137    ERROR <general>: CAESinkALSA::Initialize - failed to initialize device "default"

On the other hand, in the working scenario I can see these entries when I start playing a movie:

Code:

2021-05-28 10:46:41.127 T:5482     INFO <general>: CActiveAESink::OpenSink - initialize sink
2021-05-28 10:46:41.327 T:5478    DEBUG <general>: Sink changed
2021-05-28 10:46:41.330 T:5482    DEBUG <general>: Skipped 2 duplicate messages..
2021-05-28 10:46:41.330 T:5482    DEBUG <general>: CActiveAESink::OpenSink - trying to open device ALSA:default
2021-05-28 10:46:41.331 T:5482     INFO <general>: CAESinkALSA::Initialize - Attempting to open device "default"
2021-05-28 10:46:41.344 T:5482     INFO <general>: CAESinkALSA::Initialize - Opened device "default"

Does anyone have any idea why this is happening?

Many thanks!