OpenShot Audio Library | OpenShotAudio 0.3.2
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juce::MemoryMappedAudioFormatReader Class Referenceabstract

#include <juce_MemoryMappedAudioFormatReader.h>

Inheritance diagram for juce::MemoryMappedAudioFormatReader:
juce::AudioFormatReader

Public Member Functions

const FilegetFile () const noexcept
 
bool mapEntireFile ()
 
virtual bool mapSectionOfFile (Range< int64 > samplesToMap)
 
Range< int64 > getMappedSection () const noexcept
 
void touchSample (int64 sample) const noexcept
 
virtual void getSample (int64 sampleIndex, float *result) const noexcept=0
 
size_t getNumBytesUsed () const
 
- Public Member Functions inherited from juce::AudioFormatReader
virtual ~AudioFormatReader ()
 
const StringgetFormatName () const noexcept
 
bool read (float *const *destChannels, int numDestChannels, int64 startSampleInSource, int numSamplesToRead)
 
bool read (int *const *destChannels, int numDestChannels, int64 startSampleInSource, int numSamplesToRead, bool fillLeftoverChannelsWithCopies)
 
void read (AudioBuffer< float > *buffer, int startSampleInDestBuffer, int numSamples, int64 readerStartSample, bool useReaderLeftChan, bool useReaderRightChan)
 
virtual void readMaxLevels (int64 startSample, int64 numSamples, Range< float > *results, int numChannelsToRead)
 
virtual void readMaxLevels (int64 startSample, int64 numSamples, float &lowestLeft, float &highestLeft, float &lowestRight, float &highestRight)
 
int64 searchForLevel (int64 startSample, int64 numSamplesToSearch, double magnitudeRangeMinimum, double magnitudeRangeMaximum, int minimumConsecutiveSamples)
 
virtual AudioChannelSet getChannelLayout ()
 
virtual bool readSamples (int **destChannels, int numDestChannels, int startOffsetInDestBuffer, int64 startSampleInFile, int numSamples)=0
 

Protected Member Functions

 MemoryMappedAudioFormatReader (const File &file, const AudioFormatReader &details, int64 dataChunkStart, int64 dataChunkLength, int bytesPerFrame)
 
int64 sampleToFilePos (int64 sample) const noexcept
 
int64 filePosToSample (int64 filePos) const noexcept
 
const voidsampleToPointer (int64 sample) const noexcept
 
template<typename SampleType , typename Endianness >
Range< floatscanMinAndMaxInterleaved (int channel, int64 startSampleInFile, int64 numSamples) const noexcept
 
- Protected Member Functions inherited from juce::AudioFormatReader
 AudioFormatReader (InputStream *sourceStream, const String &formatName)
 

Protected Attributes

File file
 
Range< int64 > mappedSection
 
std::unique_ptr< MemoryMappedFilemap
 
int64 dataChunkStart
 
int64 dataLength
 
int bytesPerFrame
 

Additional Inherited Members

- Public Attributes inherited from juce::AudioFormatReader
double sampleRate = 0
 
unsigned int bitsPerSample = 0
 
int64 lengthInSamples = 0
 
unsigned int numChannels = 0
 
bool usesFloatingPointData = false
 
StringPairArray metadataValues
 
InputStreaminput
 
- Static Protected Member Functions inherited from juce::AudioFormatReader
static void clearSamplesBeyondAvailableLength (int **destChannels, int numDestChannels, int startOffsetInDestBuffer, int64 startSampleInFile, int &numSamples, int64 fileLengthInSamples)
 

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

Definition at line 47 of file juce_MemoryMappedAudioFormatReader.h.

Constructor & Destructor Documentation

◆ MemoryMappedAudioFormatReader()

juce::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.

Definition at line 393 of file juce_AudioFormatReader.cpp.

Member Function Documentation

◆ filePosToSample()

int64 juce::MemoryMappedAudioFormatReader::filePosToSample ( int64  filePos) const
inlineprotectednoexcept

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

Definition at line 96 of file juce_MemoryMappedAudioFormatReader.h.

Referenced by mapSectionOfFile().

◆ getFile()

const File & juce::MemoryMappedAudioFormatReader::getFile ( ) const
inlinenoexcept

Returns the file that is being mapped

Definition at line 62 of file juce_MemoryMappedAudioFormatReader.h.

◆ getMappedSection()

Range< int64 > juce::MemoryMappedAudioFormatReader::getMappedSection ( ) const
inlinenoexcept

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

Definition at line 71 of file juce_MemoryMappedAudioFormatReader.h.

◆ getNumBytesUsed()

size_t juce::MemoryMappedAudioFormatReader::getNumBytesUsed ( ) const
inline

Returns the number of bytes currently being mapped

Definition at line 83 of file juce_MemoryMappedAudioFormatReader.h.

◆ getSample()

virtual void juce::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.

◆ mapEntireFile()

bool juce::MemoryMappedAudioFormatReader::mapEntireFile ( )

Attempts to map the entire file into memory.

Definition at line 406 of file juce_AudioFormatReader.cpp.

◆ mapSectionOfFile()

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

Attempts to map a section of the file into memory.

Definition at line 411 of file juce_AudioFormatReader.cpp.

Referenced by mapEntireFile().

◆ sampleToFilePos()

int64 juce::MemoryMappedAudioFormatReader::sampleToFilePos ( int64  sample) const
inlineprotectednoexcept

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

Definition at line 93 of file juce_MemoryMappedAudioFormatReader.h.

Referenced by mapSectionOfFile().

◆ sampleToPointer()

const void * juce::MemoryMappedAudioFormatReader::sampleToPointer ( int64  sample) const
inlineprotectednoexcept

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

Definition at line 99 of file juce_MemoryMappedAudioFormatReader.h.

◆ scanMinAndMaxInterleaved()

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

Used by AudioFormatReader subclasses to scan for min/max ranges in interleaved data.

Definition at line 103 of file juce_MemoryMappedAudioFormatReader.h.

◆ touchSample()

void juce::MemoryMappedAudioFormatReader::touchSample ( int64  sample) const
noexcept

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

Definition at line 434 of file juce_AudioFormatReader.cpp.

Member Data Documentation

◆ bytesPerFrame

int juce::MemoryMappedAudioFormatReader::bytesPerFrame
protected

Definition at line 90 of file juce_MemoryMappedAudioFormatReader.h.

◆ dataChunkStart

int64 juce::MemoryMappedAudioFormatReader::dataChunkStart
protected

Definition at line 89 of file juce_MemoryMappedAudioFormatReader.h.

◆ dataLength

int64 juce::MemoryMappedAudioFormatReader::dataLength
protected

Definition at line 89 of file juce_MemoryMappedAudioFormatReader.h.

◆ file

File juce::MemoryMappedAudioFormatReader::file
protected

Definition at line 86 of file juce_MemoryMappedAudioFormatReader.h.

◆ map

std::unique_ptr<MemoryMappedFile> juce::MemoryMappedAudioFormatReader::map
protected

Definition at line 88 of file juce_MemoryMappedAudioFormatReader.h.

◆ mappedSection

Range<int64> juce::MemoryMappedAudioFormatReader::mappedSection
protected

Definition at line 87 of file juce_MemoryMappedAudioFormatReader.h.


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