WIP: add A2DP support, to use boombeastic as a bluetooth speaker

[afitzek]

This is still WIP, but it should already work.

[curcuz]

@afitzek nice! shall we also switch Mopidy and Shairport to pulse so that we don't have it colliding with Alsa (I can take care of that) ?

[afitzek]

Not sure if these would collide. It is working fine. Just one problem I came across is that with the builtin Bluetooth of the RPI3. If the WiFi connection is up, the Bluetooth stream becomes too slow. There are some reports on the internet, that this is a known issue with RPI3 and Zero. There seems to be some interference between these two. I will try to fix this by using an USB WiFi stick or a Bluetooth USB stick, will see what I find first.

[afitzek]

@curcuz I added a TP link wifi usb adapter to it, and now it also works with WiFi connection, but the internal wifi interface has to be disabled for bluetooth to work well.

[pardegerman]

This issue seems to be handled according to here: https://github.com/raspberrypi/linux/issues/1402

Fix is to add to the NVRAM text file located here /lib/firmware/brcm/brcmfmac<dev>-sdio.txt, where <dev> is 43430 or 43455 depending on the version of the pi used;

# Experimental Bluetooth coexistence parameters from Cypress
btc_mode=1
btc_params8=0x4e20
btc_params1=0x7530