A2DPDecoder Class Reference

Base class for a single A2DP codec's decode support: pairs an A2DP codec type and its SEP capability advertisement with an audio_tools::AudioDecoder that performs the actual decoding. Provide one concrete subclass per codec (see A2DPDecoderSBC, A2DPDecoderAAC) and register instances via BluetoothA2DPSink::add_decoder() - stream endpoint registration is driven entirely by what gets registered here. More...

#include <A2DPDecoder.h>

Inheritance diagram for A2DPDecoder:

Public Member Functions
	A2DPDecoder (audio_tools::AudioDecoder &decoder)
virtual bool	begin (const esp_a2d_mcc_t &mcc)
virtual void	build_capability (esp_a2d_mcc_t &mcc)=0
	Fills in the SEP capability advertised for this codec at registration.
virtual esp_a2d_mct_t	codec_type ()=0
	A2DP codec type this decoder handles (e.g. ESP_A2D_MCT_SBC)
virtual void	end ()
	Closes the wrapped audio_tools decoder.
audio_tools::AudioInfo	get_audio_info ()
virtual const char *	mime ()=0
	MIME type of the codec this decoder handles (e.g. "audio/sbc")
virtual size_t	write (const uint8_t *data, size_t len)

Protected Member Functions
virtual void	parse_audio_info (const esp_a2d_mcc_t &mcc)=0

Protected Attributes
int	bits_per_sample = 16
int	channels = 2
audio_tools::AudioDecoder *	p_decoder
audio_tools::CallbackStream	pcm_stream
int	sample_rate = 44100

Detailed Description

Base class for a single A2DP codec's decode support: pairs an A2DP codec type and its SEP capability advertisement with an audio_tools::AudioDecoder that performs the actual decoding. Provide one concrete subclass per codec (see A2DPDecoderSBC, A2DPDecoderAAC) and register instances via BluetoothA2DPSink::add_decoder() - stream endpoint registration is driven entirely by what gets registered here.

Author

Phil Schatzmann

Copyright

Apache License Version 2

Member Function Documentation

begin()

virtual bool A2DPDecoder::begin ( const esp_a2d_mcc_t &  mcc )

inlinevirtual

Opens the wrapped audio_tools decoder for the negotiated SEP capability: calls parse_audio_info(mcc) (implemented per codec - most decoders self-detect sample rate/channels from the encoded stream and can leave sample_rate/channels at their defaults, but codecs whose wire format doesn't carry that info per-frame, e.g. AAC, need it to synthesize the framing their decoder expects - see A2DPDecoderAAC), then wires up the PCM output and audio-info-change notification and starts the decoder.

build_capability()

virtual void A2DPDecoder::build_capability ( esp_a2d_mcc_t &  mcc )

pure virtual

Fills in the SEP capability advertised for this codec at registration.

Implemented in A2DPDecoderAAC, and A2DPDecoderSBC.

codec_type()

virtual esp_a2d_mct_t A2DPDecoder::codec_type ( )

pure virtual

A2DP codec type this decoder handles (e.g. ESP_A2D_MCT_SBC)

Implemented in A2DPDecoderAAC, and A2DPDecoderSBC.

get_audio_info()

audio_tools::AudioInfo A2DPDecoder::get_audio_info ( )

inline

Returns the most recently detected sample rate/channels (default AudioInfo values until the wrapped decoder has actually parsed them from the encoded stream)

mime()

virtual const char * A2DPDecoder::mime ( )

pure virtual

MIME type of the codec this decoder handles (e.g. "audio/sbc")

Implemented in A2DPDecoderAAC, and A2DPDecoderSBC.

parse_audio_info()

virtual void A2DPDecoder::parse_audio_info ( const esp_a2d_mcc_t &  mcc )

protectedpure virtual

Implemented in A2DPDecoderAAC, and A2DPDecoderSBC.

write()

virtual size_t A2DPDecoder::write ( const uint8_t *  data, size_t  len  )

inlinevirtual

Feeds raw encoded bytes to the wrapped decoder; decoded PCM is forwarded automatically via pcm_stream

Reimplemented in A2DPDecoderAAC.

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The documentation for this class was generated from the following files:

• src/A2DPDecoder.h
• src/A2DPDecoder.cpp