Add basic sample rate conversion to the CXD56 Spresense audio
driver using libsamplerate. Currently conversion is only done
during playback and all output is fixed at 48 kHz.
Issues:
- 16 kHz SRC has glitches (unless data dump is enabled)
- 44.1 kHz SRC gets stuck
Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
Add recording support to the Nuttx audio driver for Spresense.
- Supports 16 bit data with 48 kHz sample rate only for now.
- Supports 1 (dual mono) 2 or 4 channels.
- Only analog mics have been tested so digital is considered
unsupported.
Adds an initial Nuttx audio driver supporting the Spresense CXD56.
Being a work in progress the driver has a number of limitations:
- Audio playback only, no recording yet.
- Only 16 bit stereo playback is supported.
- In practice only 48kHz playback is supported due to missing SRC.
- Configure driver in "Device Drivers --> Audio Device Support".
