[IDEA] Add option to select SBC XQ/XQ+ encoding quality for bluetooth transmission

[jenzd]

The bluez-alsa package which is supplied with Moode already contains support for bluetooth transmission with the enhanced SBC quality modes XQ and XQ+ described in http://soundexpert.org/articles/-/blogs/...udio-codec. These are, however, not used by default. The standard SBC encoding quality is "high".

To activate one of the enhanced encoder modes, SBC quality needs to be explicitly selected by adding the switch "--sbc-quality=<mode>" when the bluealsa service is started. This can be done in the file /etc/systemd/system/bluealsa.service. Available options for <mode> are (see https://github.com/arkq/bluez-alsa/blob/...alsa.8.rst):

• low - low audio quality (mono: 114 kbps, stereo: 213 kbps)
  
• medium - medium audio quality (mono: 132 kbps, stereo: 237 kbps)
  
• high - high audio quality (mono: 198 kbps, stereo: 345 kbps)
  
• xq - SBC Dual Channel HD (SBC XQ) (452 kbps)
  
• xq+ - SBC Dual Channel HD (SBC XQ+) (551 kbps)
  

Side note: In the current version 4.1.0 of bluez-alsa the SBC XQ and XQ+ modes force the bluetooth connection to a sample rate of 44.1 kHz. Otherwise either 44.1 kHz or 48 kHz are negotiated at connection time. To force 44.1 kHz for other codecs/quality modes as well, the additional switch "--a2dp-force-audio-cd" can be used.

Idea: Would it be possible to add an option to Moode's bluetooth configuration page to select the SBC encoding quality (high/XQ /XQ+)?

Thanks & best regards
Jens