HeaderParserMP3 Class Reference

MP3 header parser that processes MP3 data incrementally and extracts complete MP3 frames. Can validate MP3 data and extract audio information. When used with a Print output, it splits incoming data into complete MP3 frames and writes them to the output stream. More...

#include <HeaderParserMP3.h>

Public Member Functions
	HeaderParserMP3 ()=default
	Default constructor.
	HeaderParserMP3 (Print &output, int bufferSize=2048)
	Constructor for write support.
int	findSyncWord (const uint8_t *buf, size_t nBytes, uint8_t synch=0xFF, uint8_t syncl=0xF0)
	Finds the mp3/aac sync word.
void	flush ()
int	getBitRate () const
	Bit rate from mp3 header.
int	getChannels () const
	Number of channels from mp3 header.
FrameHeader	getFrameHeader ()
int	getFrameLength ()
	Frame length from mp3 header.
size_t	getFrameRateHz ()
	frame rate in Hz (frames per second)
const char *	getLayerStr () const
	Provides a string representation of the MPEG layer.
size_t	getPlayingTime (size_t fileSizeBytes)
uint16_t	getSampleRate () const
	Sample rate from mp3 header.
int	getSamplesPerFrame ()
	number of samples per mp3 frame
size_t	getTimePerFrameMs ()
	playing time per frame in ms
const char *	getVersionStr () const
	Provides a string representation of the MPEG version.
bool	hasValidFrame () const
	Returns true if we have parsed at least one valid frame.
bool	isValid ()
	Returns true if a valid frame has been detected.
bool	isValid (const uint8_t *data, int len)
	parses the header string and returns true if this is a valid mp3 file
void	reset ()
	Clears internal buffer and resets state.
void	resize (int size)
void	setOutput (Print &output)
size_t	write (const uint8_t *data, size_t len)
	split up the data into mp3 segements and write to output

Protected Types
enum class	FrameReason {   VALID , INVALID_BITRATE_FOR_VERSION , INVALID_SAMPLERATE_FOR_VERSION , INVALID_MPEG_VERSION ,   INVALID_LAYER , INVALID_LAYER_II_BITRATE_AND_MODE , INVALID_EMPHASIS , INVALID_CRC }

Protected Member Functions
bool	contains (const uint8_t *data, const char *toFind, size_t len)
bool	processBuffer ()
	Processes the internal buffer to extract complete mp3 frames.
void	readFrameHeader (const uint8_t *data)
int	seekFrameSync (const uint8_t *str, size_t len)
bool	validate (const uint8_t *data, size_t len)
FrameReason	validateFrameHeader (const FrameHeader &header)

Protected Attributes
SingleBuffer< uint8_t >	buffer {0}
size_t	buffer_size = 0
bool	frame_header_valid = false
FrameHeader	header
size_t	last_frame_size = 0
Print *	p_output = nullptr

Detailed Description

MP3 header parser that processes MP3 data incrementally and extracts complete MP3 frames. Can validate MP3 data and extract audio information. When used with a Print output, it splits incoming data into complete MP3 frames and writes them to the output stream.

Features:

• Incremental processing of MP3 data in small chunks
• Frame synchronization and validation
• Extraction of audio information (sample rate, bit rate, etc.)
• Output of complete MP3 frames only
• Support for all MPEG versions (1, 2, 2.5) and layers

Author

Phil Schatzmann

Copyright

GPLv3

Member Function Documentation

getPlayingTime()

size_t getPlayingTime ( size_t  fileSizeBytes )

inline

Provides the estimated playing time in seconds based on the bitrate of the first segment

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

• src/AudioTools/AudioCodecs/HeaderParserMP3.h