DemuxerMPG Class Reference

MPEG-1 System (Program) Stream Demuxer, as defined by ISO/IEC 11172-1: splits the pack_header/system_header/PES_packet framing apart and forwards the raw MPEG-1 video (ISO/IEC 11172-2) and MPEG-1 audio (ISO/IEC 11172-3, Layer I/II/III) elementary streams to setOutputVideo()/ setOutputAudio(). Both elementary streams are self-delimiting (the video ES has its own picture_start_code sequence, the audio ES its own frame sync word) so, like DemuxerAVI/DemuxerMP4, no separate decoding is done here - point the outputs at whatever decoder understands the codec (e.g. an MPEG1 video decoder, or an EncodedAudioStream wrapping an MP3/MP2 AudioDecoder). More...

#include <ContainerMPG.h>

Inheritance diagram for DemuxerMPG:

Public Member Functions
	DemuxerMPG (int bufferSize=1024)
virtual void	addNotifyAudioChange (AudioInfoSupport &bi)
	Adds target to be notified about audio changes.
AudioInfo	audioInfo () override
	provides the actual input AudioInfo
virtual AudioInfo	audioInfoOut ()
bool	begin () override
virtual bool	begin (AudioInfo info) override
virtual void	clearNotifyAudioChange ()
	Deletes all change notify subscriptions.
void	end () override
AudioInfoFormat	getAudioInfo () override
Print *	getOutput ()
VideoInfo	getVideoInfo () override
bool	isNotifyActive ()
	Checks if the automatic AudioInfo update is active.
const char *	mime () override
	The container's MIME type (e.g. "video/avi", "video/mp4").
	operator bool () override
virtual bool	removeNotifyAudioChange (AudioInfoSupport &bi)
	Removes a target in order not to be notified about audio changes.
void	setAudioInfo (AudioInfo from) override
	for most decoders this is not needed
virtual bool	setCodecConfig (const uint8_t *data, size_t len)
	Some decoders need e.g. a magic cookie to provide the relevant info for decoding.
void	setNotifyActive (bool flag)
	Deactivate/Reactivate automatic AudioInfo updates: (default is active)
virtual void	setOutput (AudioOutput &out_stream)
	Defines where the decoded result is written to.
virtual void	setOutput (AudioStream &out_stream)
	Defines where the decoded result is written to.
void	setOutput (Print &out) override
void	setOutputAudio (Print &out) override
void	setOutputVideo (Print &out) override
void	setOutputVideo (VideoOutput &out)
void	setSendWavHeader (bool flag) override
size_t	write (const uint8_t *data, size_t len) override

Public Attributes
int	id
	custom id to be used by application

Protected Member Functions
bool	continuePayload ()
void	deliver (size_t len)
void	notifyAudioChange (AudioInfo info)
bool	parse ()
bool	parsePack ()
bool	parsePes (uint8_t id, bool isVideo)
bool	parseSkip ()
bool	parseSystemHeader ()
void	probeAudioHeader (const uint8_t *data, size_t len)
void	probeVideoHeader (const uint8_t *data, size_t len)
void	writeBlocking (Print *out, uint8_t *data, size_t len)

Static Protected Member Functions
static uint64_t	readTimestamp (const uint8_t *p)

Protected Attributes
uint8_t	audio_channels = 0
bool	audio_header_parsed = false
Vector< uint8_t >	audio_probe
uint32_t	audio_sample_rate = 0
AudioInfo	info
bool	is_notify_active = true
bool	is_parsing_active = true
bool	is_skip_unit = false
bool	is_video_unit = false
Vector< AudioInfoSupport * >	notify_vector
Print *	p_output_audio = nullptr
Print *	p_output_video = nullptr
VideoOutput *	p_output_video_video = nullptr
Print *	p_print = nullptr
MPGParseBuffer	parse_buffer
size_t	remaining = 0
uint32_t	total_bytes = 0
bool	unbounded = false
bool	unit_open = false
float	video_fps = 0
bool	video_frame_open = false
bool	video_header_parsed = false
uint16_t	video_height = 0
Vector< uint8_t >	video_probe
uint16_t	video_width = 0

Static Protected Attributes
static const size_t	VIDEO_PROBE_MAX = 64

Detailed Description

MPEG-1 System (Program) Stream Demuxer, as defined by ISO/IEC 11172-1: splits the pack_header/system_header/PES_packet framing apart and forwards the raw MPEG-1 video (ISO/IEC 11172-2) and MPEG-1 audio (ISO/IEC 11172-3, Layer I/II/III) elementary streams to setOutputVideo()/ setOutputAudio(). Both elementary streams are self-delimiting (the video ES has its own picture_start_code sequence, the audio ES its own frame sync word) so, like DemuxerAVI/DemuxerMP4, no separate decoding is done here - point the outputs at whatever decoder understands the codec (e.g. an MPEG1 video decoder, or an EncodedAudioStream wrapping an MP3/MP2 AudioDecoder).

Scope (v1): a single MPEG-1 video track (stream_id 0xE0) and a single MPEG-1 audio track (stream_id 0xC0) - the common case for files produced by encoders targeting this container (see MuxerMPG). Only the plain ISO/IEC 11172-1 pack_header (fixed 12 bytes, no stuffing) and PES header (PTS/DTS-or-none, no stuffing bytes, no STD_buffer field) are recognized; MPEG-2-style Program Streams (marker pattern '01' at the start of the pack header) are not supported.

The audio track is forwarded as a plain, continuous elementary-stream byte stream (PES packet boundaries are not required to line up with MP3/ MP2 frame boundaries - the decoder resyncs on its own frame sync word), so setOutputAudio() can point straight at an EncodedAudioStream wrapping any MPEG audio AudioDecoder (e.g. MP3DecoderHelix):

DemuxerMPG demuxer;
MP3DecoderHelix mp3;
EncodedAudioStream audioOut(&i2s, &mp3);  // MP3 -> PCM -> i2s
demuxer.setOutputAudio(audioOut);
demuxer.setOutputVideo(videoSink);
demuxer.begin();
// feed raw .mpg bytes:
demuxer.write(mpgData, len);

Author

Phil Schatzmann

Copyright

GPLv3

Constructor & Destructor Documentation

DemuxerMPG()

DemuxerMPG ( int  bufferSize = 1024 )

inline

Parameters

bufferSize

internal parse buffer size - must be able to hold at least one full pack_header/system_header/PES header (a few dozen bytes)

Member Function Documentation

addNotifyAudioChange()

virtual void addNotifyAudioChange ( AudioInfoSupport &  bi )

inlinevirtualinherited

Adds target to be notified about audio changes.

Reimplemented in CodecNOP, EncodedAudioOutput, EncodedAudioStream, AACDecoderFDK, DecoderBasic, CodecChain, MP3DecoderHelix, MP3DecoderMAD, OggContainerDecoder, RTSPClient< TcpClient, UdpSocket >, Pipeline, and Pipeline::ModifyingStreamAdapter.

audioInfo()

AudioInfo audioInfo ( )

inlineoverridevirtualinherited

provides the actual input AudioInfo

Implements AudioInfoSupport.

Reimplemented in CodecNOP, DecoderBasic, DSFDecoder, MP3DecoderHelix, MP3DecoderMAD, OpusAudioDecoder, OpusMultiStreamAudioDecoder, VorbisDecoder, WAVDecoder, WavIMADecoder, OggContainerDecoder, and VorbisDecoder.

audioInfoOut()

virtual AudioInfo audioInfoOut ( )

inlinevirtualinherited

provides the actual output AudioInfo: this is usually the same as audioInfo() unless we use a transforming stream

Reimplemented in MP3EncoderShine, PureDataStream, PWMAudioOutput< PWMDriverT >, ChannelFormatConverterStreamT< T >, ChannelFormatConverterStream, NumberFormatConverterStreamT< TFrom, TTo >, NumberFormatConverterStream, FormatConverterStream, Pipeline, ResampleStream, and ResampleStreamT< TInterpolator >.

begin() [1/2]

bool begin ( )

inlineoverridevirtual

Reimplemented from AudioDecoder.

begin() [2/2]

virtual bool begin ( AudioInfo  info )

inlineoverridevirtualinherited

Reimplemented from AudioWriter.

Reimplemented in DecoderBasic, and OggContainerDecoder.

clearNotifyAudioChange()

virtual void clearNotifyAudioChange ( )

inlinevirtualinherited

Deletes all change notify subscriptions.

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

continuePayload()

bool continuePayload ( )

inlineprotected

deliver()

void deliver ( size_t  len )

inlineprotected

end()

void end ( )

inlineoverridevirtual

Reimplemented from AudioDecoder.

getAudioInfo()

AudioInfoFormat getAudioInfo ( )

inlineoverridevirtual

Common audio info, parsed from the audio ES's own MPEG audio frame header once seen - falls back to 44100/stereo if not yet available.

Implements Demuxer.

getOutput()

Print * getOutput ( )

inlineinherited

getVideoInfo()

VideoInfo getVideoInfo ( )

inlineoverridevirtual

Common video info (width/height/fps/format), parsed from the video ES's own sequence_header (ISO/IEC 11172-2) once seen - all zero/ VideoFormat::MPEG1 until then.

Implements Demuxer.

isNotifyActive()

bool isNotifyActive ( )

inlineinherited

Checks if the automatic AudioInfo update is active.

mime()

const char * mime ( )

inlineoverridevirtual

The container's MIME type (e.g. "video/avi", "video/mp4").

Implements Demuxer.

notifyAudioChange()

void notifyAudioChange ( AudioInfo  info )

inlineprotectedinherited

operator bool()

operator bool ( )

inlineoverridevirtual

Implements AudioWriter.

parse()

bool parse ( )

inlineprotected

Parses/consumes as much as is currently buffered; returns true if progress was made (call again - more units may already be buffered), false if it needs more data (wait for the next write()).

parsePack()

bool parsePack ( )

inlineprotected

parsePes()

bool parsePes ( uint8_t  id, bool  isVideo  )

inlineprotected

parseSkip()

bool parseSkip ( )

inlineprotected

program_stream_map / private_stream_1 / padding_stream / private_stream_2: same PES_packet_length-prefixed framing, payload discarded.

parseSystemHeader()

bool parseSystemHeader ( )

inlineprotected

probeAudioHeader()

void probeAudioHeader ( const uint8_t *  data, size_t  len  )

inlineprotected

Inspects the first 4 bytes of the audio ES for an MPEG audio frame header (ISO/IEC 11172-3) to determine sample_rate/channels.

probeVideoHeader()

void probeVideoHeader ( const uint8_t *  data, size_t  len  )

inlineprotected

Accumulates the first bytes of the video ES looking for its sequence_header (00 00 01 B3) to determine width/height/fps - harmless to keep calling once found, since video_header_parsed then short-circuits it.

readTimestamp()

static uint64_t readTimestamp ( const uint8_t *  p )

inlinestaticprotected

Reads a single 5-byte MPEG-1 timestamp field (PTS or DTS - both use the same bit layout, only the leading 4-bit id nibble differs, which is not part of this 5-byte window) at 'p'.

removeNotifyAudioChange()

virtual bool removeNotifyAudioChange ( AudioInfoSupport &  bi )

inlinevirtualinherited

Removes a target in order not to be notified about audio changes.

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

setAudioInfo()

void setAudioInfo ( AudioInfo  from )

inlineoverridevirtualinherited

for most decoders this is not needed

Implements AudioWriter.

Reimplemented in DecoderALAC, CodecChain, DSFDecoder, DecoderL8, OpusAudioDecoder, OpusMultiStreamAudioDecoder, CodecNOP, G729Decoder, and G7xxDecoder.

setCodecConfig()

virtual bool setCodecConfig ( const uint8_t *  data, size_t  len  )

inlinevirtualinherited

Some decoders need e.g. a magic cookie to provide the relevant info for decoding.

Reimplemented in DecoderALAC, and MultiDecoder.

setNotifyActive()

void setNotifyActive ( bool  flag )

inlineinherited

Deactivate/Reactivate automatic AudioInfo updates: (default is active)

setOutput() [1/3]

virtual void setOutput ( AudioOutput &  out_stream )

inlinevirtualinherited

Defines where the decoded result is written to.

Reimplemented in ADTSDecoder, CodecChain, MTSDecoder, MTSDecoderTSDemux, and MetaDataFilterDecoder.

setOutput() [2/3]

virtual void setOutput ( AudioStream &  out_stream )

inlinevirtualinherited

Defines where the decoded result is written to.

Reimplemented in ADTSDecoder, CodecChain, MTSDecoder, MTSDecoderTSDemux, and MetaDataFilterDecoder.

setOutput() [3/3]

void setOutput ( Print &  out )

inlineoverridevirtual

Satisfies the AudioWriter/AudioDecoder interface - needed so EncodedAudioOutput/EncodedAudioStream's polymorphic AudioDecoder* wiring reaches the audio output correctly; delegates to setOutputAudio().

Reimplemented from AudioDecoder.

setOutputAudio()

void setOutputAudio ( Print &  out )

inlineoverridevirtual

Defines the audio output stream - e.g. an EncodedAudioStream wrapping an MP3/MP2 AudioDecoder, or any other Print if you want the raw payload as-is.

Implements Demuxer.

setOutputVideo() [1/2]

void setOutputVideo ( Print &  out )

inlineoverridevirtual

Defines the video output - e.g. a VideoOutput implementation, or any other Print if you want the raw MPEG-1 video ES as-is.

Implements Demuxer.

setOutputVideo() [2/2]

void setOutputVideo ( VideoOutput &  out )

inline

setSendWavHeader()

void setSendWavHeader ( bool  flag )

inlineoverridevirtual

Not applicable: MPEG-1 audio (Layer I/II/III) is compressed and self-framed (its own sync word), unlike PCM - it never needs a synthetic WAV header. Provided only to satisfy the Demuxer interface.

Implements Demuxer.

write()

size_t write ( const uint8_t *  data, size_t  len  )

inlineoverridevirtual

Implements AudioWriter.

writeBlocking()

void writeBlocking ( Print *  out, uint8_t *  data, size_t  len  )

inlineprotectedinherited

Member Data Documentation

audio_channels

uint8_t audio_channels = 0

protected

audio_header_parsed

bool audio_header_parsed = false

protected

audio_probe

Vector<uint8_t> audio_probe

protected

audio_sample_rate

uint32_t audio_sample_rate = 0

protected

id

int id

inherited

custom id to be used by application

info

AudioInfo info

protectedinherited

is_notify_active

bool is_notify_active = true

protectedinherited

is_parsing_active

bool is_parsing_active = true

protected

is_skip_unit

bool is_skip_unit = false

protected

is_video_unit

bool is_video_unit = false

protected

notify_vector

Vector<AudioInfoSupport*> notify_vector

protectedinherited

p_output_audio

Print* p_output_audio = nullptr

protected

p_output_video

Print* p_output_video = nullptr

protected

p_output_video_video

VideoOutput* p_output_video_video = nullptr

protected

p_print

Print* p_print = nullptr

protectedinherited

parse_buffer

MPGParseBuffer parse_buffer

protected

remaining

size_t remaining = 0

protected

total_bytes

uint32_t total_bytes = 0

protected

unbounded

bool unbounded = false

protected

unit_open

bool unit_open = false

protected

video_fps

float video_fps = 0

protected

video_frame_open

bool video_frame_open = false

protected

video_header_parsed

bool video_header_parsed = false

protected

video_height

uint16_t video_height = 0

protected

video_probe

Vector<uint8_t> video_probe

protected

VIDEO_PROBE_MAX

const size_t VIDEO_PROBE_MAX = 64

staticprotected

video_width

uint16_t video_width = 0

protected

---

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

• src/AudioTools/AudioCodecs/ContainerMPG.h