shaka::media::mp2t::Mpeg1Header Class Reference

#include <mpeg1_header.h>

Inheritance diagram for shaka::media::mp2t::Mpeg1Header:

Public Member Functions
AudioHeader implementation overrides.
bool	IsSyncWord (const uint8_t *buf) const override
size_t	GetMinFrameSize () const override
size_t	GetSamplesPerFrame () const override
bool	Parse (const uint8_t *mpeg1_frame, size_t mpeg1_frame_size) override
size_t	GetHeaderSize () const override
size_t	GetFrameSize () const override
size_t	GetFrameSizeWithoutParsing (const uint8_t *data, size_t num_bytes) const override
void	GetAudioSpecificConfig (std::vector< uint8_t > *buffer) const override
uint8_t	GetObjectType () const override
uint32_t	GetSamplingFrequency () const override
uint8_t	GetNumChannels () const override

Detailed Description

Class which parses Mpeg1 audio frame (header / metadata) and synthesizes AudioSpecificConfig from audio frame content.

See https://www.datavoyage.com/mpgscript/mpeghdr.htm

Definition at line 16 of file mpeg1_header.h.

Member Function Documentation

GetAudioSpecificConfig()

void shaka::media::mp2t::Mpeg1Header::GetAudioSpecificConfig ( std::vector< uint8_t > *  buffer ) const

overridevirtual

Synthesize an AudioSpecificConfig record from the fields within the audio header. Should only be called after a successful Parse.

Parameters

[out]

buffer

is a pointer to a vector to contain the AudioSpecificConfig.

Returns

true if successful, false otherwise.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 190 of file mpeg1_header.cc.

GetFrameSize()

size_t shaka::media::mp2t::Mpeg1Header::GetFrameSize ( ) const

overridevirtual

Should only be called after a successful Parse.

Returns

the size of frame (header + payload).

Implements shaka::media::mp2t::AudioHeader.

Definition at line 168 of file mpeg1_header.cc.

GetFrameSizeWithoutParsing()

size_t shaka::media::mp2t::Mpeg1Header::GetFrameSizeWithoutParsing ( const uint8_t *  data, size_t  num_bytes  ) const

overridevirtual

Obtain the size of the frame from the header data without doing a full Parse.

Returns

the size of the frame (header + payload).

Implements shaka::media::mp2t::AudioHeader.

Definition at line 172 of file mpeg1_header.cc.

GetHeaderSize()

size_t shaka::media::mp2t::Mpeg1Header::GetHeaderSize ( ) const

overridevirtual

Should only be called after a successful Parse.

Returns

The size of audio header.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 162 of file mpeg1_header.cc.

GetMinFrameSize()

size_t shaka::media::mp2t::Mpeg1Header::GetMinFrameSize ( ) const

overridevirtual

Returns

The minium frame size.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 111 of file mpeg1_header.cc.

GetNumChannels()

uint8_t shaka::media::mp2t::Mpeg1Header::GetNumChannels ( ) const

overridevirtual

Should only be called after a successful Parse.

Returns

Number of channels for this frame.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 243 of file mpeg1_header.cc.

GetObjectType()

uint8_t shaka::media::mp2t::Mpeg1Header::GetObjectType ( ) const

overridevirtual

Should only be called after a successful Parse.

Returns

The audio profile for this frame. Only meaningful for AAC.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 226 of file mpeg1_header.cc.

GetSamplesPerFrame()

size_t shaka::media::mp2t::Mpeg1Header::GetSamplesPerFrame ( ) const

overridevirtual

Returns

Number of audio samples per frame.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 115 of file mpeg1_header.cc.

GetSamplingFrequency()

uint32_t shaka::media::mp2t::Mpeg1Header::GetSamplingFrequency ( ) const

overridevirtual

Should only be called after a successful Parse.

Returns

The sampling frequency for this frame.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 239 of file mpeg1_header.cc.

IsSyncWord()

bool shaka::media::mp2t::Mpeg1Header::IsSyncWord ( const uint8_t *  buf ) const

overridevirtual

Check if the leading word (2 bytes) is sync signal.

Parameters

buf	points to the buffer to be checked. Must be at least 2 bytes.

Returns

true if corresponds to a syncword.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 102 of file mpeg1_header.cc.

Parse()

bool shaka::media::mp2t::Mpeg1Header::Parse ( const uint8_t *  audio_frame, size_t  audio_frame_size  )

overridevirtual

Parse a partial audio frame, extracting the fields within. Only audio frame header / metadata is parsed. The audio_frame_size must contain the full header / metadata.

Parameters

audio_frame	is an input parameter pointing to an audio frame.
audio_frame_size	is the size, in bytes of the input data. It can be smaller than the actual frame size, but it should not be smaller than the header size.

Returns

true if successful, false otherwise.

Implements shaka::media::mp2t::AudioHeader.

Definition at line 121 of file mpeg1_header.cc.

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

• packager/media/formats/mp2t/mpeg1_header.h
• packager/media/formats/mp2t/mpeg1_header.cc