M4ACommonDemuxer::SampleExtractor Class Reference

Extracts audio data based on the sample sizes defined in the stsz box. It collects the data from the mdat box and calls the callback with the extracted frames. More...

#include <M4ACommonDemuxer.h>

Public Types
using	Codec = M4ACommonDemuxer::Codec
using	Frame = M4ACommonDemuxer::Frame
using	FrameCallback = std::function< void(const Frame &, void *)>
using	M4AAudioConfig = M4ACommonDemuxer::M4AAudioConfig

Public Member Functions
	SampleExtractor (M4AAudioConfig &cfg)
	Constructor. Initializes the extractor.
void	begin ()
	Resets the extractor state.
BaseBuffer< uint32_t > &	getChunkOffsetsBuffer ()
	Returns the buffer of chunk offsets.
Frame	getFrame (size_t size, SingleBuffer< uint8_t > &buffer)
	Constructs a Frame object for the current codec.
BaseBuffer< stsz_sample_size_t > &	getSampleSizesBuffer ()
	Returns the buffer of sample sizes.
void	setCallback (FrameCallback cb)
	Sets the callback to be called for each extracted frame.
void	setChunkOffsetsBuffer (BaseBuffer< uint32_t > &buffer)
	Sets the buffer to use for chunk offsets.
void	setFixedSampleCount (uint32_t sampleSize, uint32_t sampleCount)
	Sets a fixed sample size/count instead of using the sampleSizes table.
void	setMaxSize (size_t size)
	Sets the maximum box size (e.g., for mdat). This is called before the mdat data is posted. In order to be able to play a file multiple times we just reset the sampleIndex!
void	setReference (void *r)
	Sets a reference pointer passed to the callback.
void	setSampleSizesBuffer (BaseBuffer< stsz_sample_size_t > &buffer)
	Sets the buffer to use for sample sizes.
size_t	write (const uint8_t *data, size_t len, bool is_final)
	Writes data to the extractor, extracting frames as sample sizes are met. Provides the data via the callback.

Protected Member Functions
size_t	currentSampleSize ()
	Returns the current sample size.
void	executeCallback (size_t size)
	Executes the callback for a completed frame.
void	resize (size_t newSize)
	Resizes the internal buffer if needed.

Static Protected Member Functions
static void	writeAdtsHeader (uint8_t *adts, int aacProfile, int sampleRateIdx, int channelCfg, int frameLen)
	Writes an ADTS header for an AAC frame.

Protected Attributes
M4AAudioConfig &	audio_config
size_t	box_pos = 0
	Current position in the box.
size_t	box_size = 0
	Maximum size of the current sample.
SingleBuffer< uint8_t >	buffer
	Buffer for accumulating sample data.
FrameCallback	callback = nullptr
	Frame callback.
size_t	current_size = 0
	Current sample size.
SingleBuffer< uint32_t >	defaultChunkOffsets
	Table of chunk offsets.
SingleBuffer< stsz_sample_size_t >	defaultSampleSizes
	Table of sample sizes.
uint32_t	fixed_sample_count = 0
	Fixed sample count (if used).
uint32_t	fixed_sample_size = 0
	Fixed sample size (if used).
BaseBuffer< uint32_t > *	p_chunk_offsets = &defaultChunkOffsets
BaseBuffer< stsz_sample_size_t > *	p_sample_sizes = &defaultSampleSizes
void *	ref = nullptr
	Reference pointer for callback.
size_t	sampleIndex = 0
	Current sample index.
Vector< uint8_t >	tmp

Detailed Description

Extracts audio data based on the sample sizes defined in the stsz box. It collects the data from the mdat box and calls the callback with the extracted frames.

Member Typedef Documentation

Codec

using Codec = M4ACommonDemuxer::Codec

Frame

using Frame = M4ACommonDemuxer::Frame

FrameCallback

using FrameCallback = std::function<void(const Frame&, void*)>

M4AAudioConfig

using M4AAudioConfig = M4ACommonDemuxer::M4AAudioConfig

Constructor & Destructor Documentation

SampleExtractor()

SampleExtractor ( M4AAudioConfig &  cfg )

inline

Constructor. Initializes the extractor.

Member Function Documentation

begin()

void begin ( )

inline

Resets the extractor state.

currentSampleSize()

size_t currentSampleSize ( )

inlineprotected

Returns the current sample size.

Returns

Size of the current sample.

executeCallback()

void executeCallback ( size_t  size )

inlineprotected

Executes the callback for a completed frame.

Parameters

size	Size of the frame.

getChunkOffsetsBuffer()

BaseBuffer< uint32_t > & getChunkOffsetsBuffer ( )

inline

Returns the buffer of chunk offsets.

Returns

Reference to the buffer of chunk offsets.

getFrame()

Frame getFrame ( size_t  size, SingleBuffer< uint8_t > &  buffer  )

inline

Constructs a Frame object for the current codec.

Parameters

size	Size of the frame.
buffer	SingleBuffer with data.

Returns

Frame object.

getSampleSizesBuffer()

BaseBuffer< stsz_sample_size_t > & getSampleSizesBuffer ( )

inline

Returns the buffer of sample sizes.

Returns

Reference to the buffer of sample sizes.

resize()

void resize ( size_t  newSize )

inlineprotected

Resizes the internal buffer if needed.

Parameters

newSize

New buffer size.

setCallback()

void setCallback ( FrameCallback  cb )

inline

Sets the callback to be called for each extracted frame.

Parameters

cb	Callback function.

setChunkOffsetsBuffer()

void setChunkOffsetsBuffer ( BaseBuffer< uint32_t > &  buffer )

inline

Sets the buffer to use for chunk offsets.

Parameters

buffer

Reference to the buffer to use.

setFixedSampleCount()

void setFixedSampleCount ( uint32_t  sampleSize, uint32_t  sampleCount  )

inline

Sets a fixed sample size/count instead of using the sampleSizes table.

Parameters

sampleSize	Size of each sample.
sampleCount	Number of samples.

setMaxSize()

void setMaxSize ( size_t  size )

inline

Sets the maximum box size (e.g., for mdat). This is called before the mdat data is posted. In order to be able to play a file multiple times we just reset the sampleIndex!

Parameters

size	Maximum size in bytes.

setReference()

void setReference ( void *  r )

inline

Sets a reference pointer passed to the callback.

Parameters

r	Reference pointer.

setSampleSizesBuffer()

void setSampleSizesBuffer ( BaseBuffer< stsz_sample_size_t > &  buffer )

inline

Sets the buffer to use for sample sizes.

Parameters

buffer

Reference to the buffer to use.

write()

size_t write ( const uint8_t *  data, size_t  len, bool  is_final  )

inline

Writes data to the extractor, extracting frames as sample sizes are met. Provides the data via the callback.

Parameters

data	Pointer to input data.
len	Length of input data.
is_final	True if this is the last chunk of the box.

Returns

Number of bytes processed.

fill buffer up to the current sample size

writeAdtsHeader()

static void writeAdtsHeader ( uint8_t *  adts, int  aacProfile, int  sampleRateIdx, int  channelCfg, int  frameLen  )

inlinestaticprotected

Writes an ADTS header for an AAC frame.

Parameters

adts	Output buffer for the header.
aacProfile	AAC profile.
sampleRateIdx	Sample rate index.
channelCfg	Channel configuration.
frameLen	Frame length.

Member Data Documentation

audio_config

M4AAudioConfig& audio_config

protected

box_pos

size_t box_pos = 0

protected

Current position in the box.

box_size

size_t box_size = 0

protected

Maximum size of the current sample.

buffer

SingleBuffer<uint8_t> buffer

protected

Buffer for accumulating sample data.

callback

FrameCallback callback = nullptr

protected

Frame callback.

current_size

size_t current_size = 0

protected

Current sample size.

defaultChunkOffsets

SingleBuffer<uint32_t> defaultChunkOffsets

protected

Table of chunk offsets.

defaultSampleSizes

SingleBuffer<stsz_sample_size_t> defaultSampleSizes

protected

Table of sample sizes.

fixed_sample_count

uint32_t fixed_sample_count = 0

protected

Fixed sample count (if used).

fixed_sample_size

uint32_t fixed_sample_size = 0

protected

Fixed sample size (if used).

p_chunk_offsets

BaseBuffer<uint32_t>* p_chunk_offsets = &defaultChunkOffsets

protected

p_sample_sizes

BaseBuffer<stsz_sample_size_t>* p_sample_sizes = &defaultSampleSizes

protected

ref

void* ref = nullptr

protected

Reference pointer for callback.

sampleIndex

size_t sampleIndex = 0

protected

Current sample index.

tmp

Vector<uint8_t> tmp

protected

---

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

• src/AudioTools/AudioCodecs/M4ACommonDemuxer.h