Here are the classes, structs, unions and interfaces with brief descriptions:

CA2DPDefaultVolumeControl	Default implementation for handling of the volume of the audio data
CA2DPLinearVolumeControl	The simplest possible implementation of a VolumeControl
CA2DPNoVolumeControl	Keeps the audio data as is -> no volume control!
CA2DPSimpleExponentialVolumeControl	Exponentional volume control
CA2DPVolumeControl	Abstract class for handling of the volume of the audio data
CBluetoothA2DPCommon	Common Bluetooth A2DP functions
CBluetoothA2DPOutput	Abstract Output Class
CBluetoothA2DPOutputAudioTools	Output Class using AudioTools library: https://github.com/pschatzmann/arduino-audio-tools
CBluetoothA2DPOutputDefault	Default Output Class providing both the Legacy I2S and the AudioTools I2S functionality
CBluetoothA2DPOutputLegacy	Legacy I2S Output Class
CBluetoothA2DPOutputPrint	Output Class using Print API:
CBluetoothA2DPSink	A2DP Bluethooth Sink - We initialize and start the Bluetooth A2DP Sink. The example https://github.com/espressif/esp-idf/tree/master/examples/bluetooth/bluedroid/classic_bt/a2dp_sink was refactered into a C++ class
CBluetoothA2DPSinkQueued	The BluetoothA2DPSinkQueued is using a separate Task with an additinal Queue to write the I2S data. application
CBluetoothA2DPSource	A2DP Bluetooth Source
Cbt_app_msg_t	Internal message to be sent for BluetoothA2DPSink and BluetoothA2DPSource