This is a audio_hal component for AI-Thinker's ESP32-A1S  module respectively ESP32 Audio Kit . The audio_hal component shipped with the esp-adf  unfortunately doesn't provide any interface to add third-party codec. This is based on AI-Thinker's code , which is an esp-adf fork with modifications for this codec (AC101).
How to use:
Clone this repository into components/audio_hal of your esp-adf project:
cd /path/to/your/project git clone https://github.com/phkehl/esp32-a1s-audio_hal.git components/audio_hal
Or add it as a git submodule:
cd /path/to/your/project git submodule add -b master https://github.com/phkehl/esp32-a1s-audio_hal.git components/audio_hal
This will then take precedence over the one in $ADF_PATH/components/audio_hal.
The modifications to audio_hal.h and audio_hal.h are very minimal and upgrading this with later versions of the esp-adf should be easy. There is one additional function esp_err_t audio_hal_pa_power(bool enable) not present in the original code. Use this to controls the power of the power amplifier on AI's ESP32 Audio Kit board.
There is an example in the example subdirectory. Note the symlink example/components/audio_hal.