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defaults: ucm2: Rework ALSA UCM profiles

Sebastian Krzyszkowiak requested to merge sebastian.krzyszkowiak/librem5-base:audio-rework into pureos/byzantium

This is a bigger overhaul of the profiles inspired by studying WM8962 datasheet and debugging issues with PulseAudio.

Aside of a general cleanup, it changes several things aimed to improve audio quality on both inputs and outputs.

The new profile:

  • allows PulseAudio to use hardware volume control and makes sure that PGA gains are user-configurable
  • makes sure Zero-Cross feature is enabled for all relevant input and output paths
  • enables High-Pass Filters to protect the speakers from potential damage, get rid of DC offset and to improve input speech legibility
  • minimizes the amount of gains used in various paths
  • makes "Speaker" profile use both speakers, each with the same downmixed mono signal, which improves volume and frequency response
  • uses HD Bass feature for improved lower frequency response of internal speakers
  • uses only the bottom microphone by default and duplicates it into both stereo channels (and creates a new "stereo microphones" device, so users can still access both microphones when desired)
  • duplicates analog microphone signal into both stereo channels
  • enables High Performance modes for better signal to noise ratio
  • uses Dynamic Range Control for input path to control signal level and attenuate background noise
  • switches to wired microphone automatically after plugging in (requires linux!583 (merged))

In addition, this MR also:

  • sets modem's input volume to 50% to avoid modem-side clipping
  • enables voice legibility enhancement and noise suppression in PA's echo-cancel module
Edited by Sebastian Krzyszkowiak

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