A specialised type of AudioFormatReader that uses a MemoryMappedFile to read directly from an audio file. More...

Inheritance diagram for MemoryMappedAudioFormatReader:

Public Member Functions

const FilegetFile () const noexcept
 Returns the file that is being mapped. More...
 
bool mapEntireFile ()
 Attempts to map the entire file into memory. More...
 
virtual bool mapSectionOfFile (Range< int64 > samplesToMap)
 Attempts to map a section of the file into memory. More...
 
Range< int64getMappedSection () const noexcept
 Returns the sample range that's currently memory-mapped and available for reading. More...
 
void touchSample (int64 sample) const noexcept
 Touches the memory for the given sample, to force it to be loaded into active memory. More...
 
virtual void getSample (int64 sampleIndex, float *result) const noexcept=0
 Returns the samples for all channels at a given sample position. More...
 
size_t getNumBytesUsed () const
 Returns the number of bytes currently being mapped. More...
 
- Public Member Functions inherited from AudioFormatReader
virtual ~AudioFormatReader ()
 Destructor. More...
 
const StringgetFormatName () const noexcept
 Returns a description of what type of format this is. More...
 
bool read (int *const *destSamples, int numDestChannels, int64 startSampleInSource, int numSamplesToRead, bool fillLeftoverChannelsWithCopies)
 Reads samples from the stream. More...
 
void read (AudioSampleBuffer *buffer, int startSampleInDestBuffer, int numSamples, int64 readerStartSample, bool useReaderLeftChan, bool useReaderRightChan)
 Fills a section of an AudioSampleBuffer from this reader. More...
 
virtual void readMaxLevels (int64 startSample, int64 numSamples, Range< float > *results, int numChannelsToRead)
 Finds the highest and lowest sample levels from a section of the audio stream. More...
 
virtual void readMaxLevels (int64 startSample, int64 numSamples, float &lowestLeft, float &highestLeft, float &lowestRight, float &highestRight)
 Finds the highest and lowest sample levels from a section of the audio stream. More...
 
int64 searchForLevel (int64 startSample, int64 numSamplesToSearch, double magnitudeRangeMinimum, double magnitudeRangeMaximum, int minimumConsecutiveSamples)
 Scans the source looking for a sample whose magnitude is in a specified range. More...
 
virtual AudioChannelSet getChannelLayout ()
 Get the channel layout of the audio stream. More...
 
virtual bool readSamples (int **destSamples, int numDestChannels, int startOffsetInDestBuffer, int64 startSampleInFile, int numSamples)=0
 Subclasses must implement this method to perform the low-level read operation. More...
 

Protected Member Functions

 MemoryMappedAudioFormatReader (const File &file, const AudioFormatReader &details, int64 dataChunkStart, int64 dataChunkLength, int bytesPerFrame)
 Creates an MemoryMappedAudioFormatReader object. More...
 
int64 sampleToFilePos (int64 sample) const noexcept
 Converts a sample index to a byte position in the file. More...
 
int64 filePosToSample (int64 filePos) const noexcept
 Converts a byte position in the file to a sample index. More...
 
const void * sampleToPointer (int64 sample) const noexcept
 Converts a sample index to a pointer to the mapped file memory. More...
 
template<typename SampleType , typename Endianness >
Range< float > scanMinAndMaxInterleaved (int channel, int64 startSampleInFile, int64 numSamples) const noexcept
 Used by AudioFormatReader subclasses to scan for min/max ranges in interleaved data. More...
 
- Protected Member Functions inherited from AudioFormatReader
 AudioFormatReader (InputStream *sourceStream, const String &formatName)
 Creates an AudioFormatReader object. More...
 

Protected Attributes

File file
 
Range< int64mappedSection
 
ScopedPointer< MemoryMappedFilemap
 
int64 dataChunkStart
 
int64 dataLength
 
int bytesPerFrame
 

Additional Inherited Members

- Public Attributes inherited from AudioFormatReader
double sampleRate = 0
 The sample-rate of the stream. More...
 
unsigned int bitsPerSample = 0
 The number of bits per sample, e.g. More...
 
int64 lengthInSamples = 0
 The total number of samples in the audio stream. More...
 
unsigned int numChannels = 0
 The total number of channels in the audio stream. More...
 
bool usesFloatingPointData = false
 Indicates whether the data is floating-point or fixed. More...
 
StringPairArray metadataValues
 A set of metadata values that the reader has pulled out of the stream. More...
 
InputStreaminput
 The input stream, for use by subclasses. More...
 
- Static Protected Member Functions inherited from AudioFormatReader
static void clearSamplesBeyondAvailableLength (int **destSamples, int numDestChannels, int startOffsetInDestBuffer, int64 startSampleInFile, int &numSamples, int64 fileLengthInSamples)
 Used by AudioFormatReader subclasses to clear any parts of the data blocks that lie beyond the end of their available length. More...
 

Detailed Description

A specialised type of AudioFormatReader that uses a MemoryMappedFile to read directly from an audio file.

This allows for incredibly fast random-access to sample data in the mapped region of the file, but not all audio formats support it - see AudioFormat::createMemoryMappedReader().

Note that before reading samples from a MemoryMappedAudioFormatReader, you must first call mapEntireFile() or mapSectionOfFile() to ensure that the region you want to read has been mapped.

See also
AudioFormat::createMemoryMappedReader, AudioFormatReader

Constructor & Destructor Documentation

◆ MemoryMappedAudioFormatReader()

MemoryMappedAudioFormatReader::MemoryMappedAudioFormatReader ( const File file,
const AudioFormatReader details,
int64  dataChunkStart,
int64  dataChunkLength,
int  bytesPerFrame 
)
protected

Creates an MemoryMappedAudioFormatReader object.

Note that before attempting to read any data, you must call mapEntireFile() or mapSectionOfFile() to ensure that the region you want to read has been mapped.

Member Function Documentation

◆ getFile()

const File& MemoryMappedAudioFormatReader::getFile ( ) const
noexcept

Returns the file that is being mapped.

◆ mapEntireFile()

bool MemoryMappedAudioFormatReader::mapEntireFile ( )

Attempts to map the entire file into memory.

◆ mapSectionOfFile()

virtual bool MemoryMappedAudioFormatReader::mapSectionOfFile ( Range< int64 samplesToMap)
virtual

Attempts to map a section of the file into memory.

◆ getMappedSection()

Range<int64> MemoryMappedAudioFormatReader::getMappedSection ( ) const
noexcept

Returns the sample range that's currently memory-mapped and available for reading.

◆ touchSample()

void MemoryMappedAudioFormatReader::touchSample ( int64  sample) const
noexcept

Touches the memory for the given sample, to force it to be loaded into active memory.

◆ getSample()

virtual void MemoryMappedAudioFormatReader::getSample ( int64  sampleIndex,
float *  result 
) const
pure virtualnoexcept

Returns the samples for all channels at a given sample position.

The result array must be large enough to hold a value for each channel that this reader contains.

◆ getNumBytesUsed()

size_t MemoryMappedAudioFormatReader::getNumBytesUsed ( ) const

Returns the number of bytes currently being mapped.

References map().

◆ sampleToFilePos()

int64 MemoryMappedAudioFormatReader::sampleToFilePos ( int64  sample) const
protectednoexcept

Converts a sample index to a byte position in the file.

◆ filePosToSample()

int64 MemoryMappedAudioFormatReader::filePosToSample ( int64  filePos) const
protectednoexcept

Converts a byte position in the file to a sample index.

◆ sampleToPointer()

const void* MemoryMappedAudioFormatReader::sampleToPointer ( int64  sample) const
protectednoexcept

Converts a sample index to a pointer to the mapped file memory.

References addBytesToPointer(), MemoryMappedFile::getData(), MemoryMappedFile::getRange(), and Range< ValueType >::getStart().

◆ scanMinAndMaxInterleaved()

template<typename SampleType , typename Endianness >
Range<float> MemoryMappedAudioFormatReader::scanMinAndMaxInterleaved ( int  channel,
int64  startSampleInFile,
int64  numSamples 
) const
protectednoexcept

Member Data Documentation

◆ file

File MemoryMappedAudioFormatReader::file
protected

◆ mappedSection

Range<int64> MemoryMappedAudioFormatReader::mappedSection
protected

◆ map

ScopedPointer<MemoryMappedFile> MemoryMappedAudioFormatReader::map
protected

◆ dataChunkStart

int64 MemoryMappedAudioFormatReader::dataChunkStart
protected

◆ dataLength

int64 MemoryMappedAudioFormatReader::dataLength
protected

◆ bytesPerFrame

int MemoryMappedAudioFormatReader::bytesPerFrame
protected

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