Public Member Functions | List of all members
AudioSubsectionReader Class Reference

This class is used to wrap an AudioFormatReader and only read from a subsection of the file. More...

Inheritance diagram for AudioSubsectionReader:

Public Member Functions

 AudioSubsectionReader (AudioFormatReader *sourceReader, int64 subsectionStartSample, int64 subsectionLength, bool deleteSourceWhenDeleted)
 Creates an AudioSubsectionReader for a given data source. More...
 
 ~AudioSubsectionReader ()
 Destructor. More...
 
bool readSamples (int **destSamples, int numDestChannels, int startOffsetInDestBuffer, int64 startSampleInFile, int numSamples) override
 Subclasses must implement this method to perform the low-level read operation. More...
 
void readMaxLevels (int64 startSample, int64 numSamples, Range< float > *results, int numChannelsToRead) override
 Finds the highest and lowest sample levels from a section of the audio stream. 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 (AudioBuffer< float > *buffer, int startSampleInDestBuffer, int numSamples, int64 readerStartSample, bool useReaderLeftChan, bool useReaderRightChan)
 Fills a section of an AudioBuffer from this reader. 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...
 

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...
 
- Protected Member Functions inherited from AudioFormatReader
 AudioFormatReader (InputStream *sourceStream, const String &formatName)
 Creates an AudioFormatReader object. 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

This class is used to wrap an AudioFormatReader and only read from a subsection of the file.

So if you have a reader which can read a 1000 sample file, you could wrap it in one of these to only access, e.g. samples 100 to 200, and any samples outside that will come back as 0. Accessing sample 0 from this reader will actually read the first sample from the other's subsection, which might be at a non-zero position.

See also
AudioFormatReader

Constructor & Destructor Documentation

◆ AudioSubsectionReader()

AudioSubsectionReader::AudioSubsectionReader ( AudioFormatReader sourceReader,
int64  subsectionStartSample,
int64  subsectionLength,
bool  deleteSourceWhenDeleted 
)

Creates an AudioSubsectionReader for a given data source.

Parameters
sourceReaderthe source reader from which we'll be taking data
subsectionStartSamplethe sample within the source reader which will be mapped onto sample 0 for this reader.
subsectionLengththe number of samples from the source that will make up the subsection. If this reader is asked for any samples beyond this region, it will return zero.
deleteSourceWhenDeletedif true, the sourceReader object will be deleted when this object is deleted.

◆ ~AudioSubsectionReader()

AudioSubsectionReader::~AudioSubsectionReader ( )

Destructor.

Member Function Documentation

◆ readSamples()

bool AudioSubsectionReader::readSamples ( int **  destSamples,
int  numDestChannels,
int  startOffsetInDestBuffer,
int64  startSampleInFile,
int  numSamples 
)
overridevirtual

Subclasses must implement this method to perform the low-level read operation.

Callers should use read() instead of calling this directly.

Parameters
destSamplesthe array of destination buffers to fill. Some of these pointers may be null
numDestChannelsthe number of items in the destSamples array. This value is guaranteed not to be greater than the number of channels that this reader object contains
startOffsetInDestBufferthe number of samples from the start of the dest data at which to begin writing
startSampleInFilethe number of samples into the source data at which to begin reading. This value is guaranteed to be >= 0.
numSamplesthe number of samples to read

Implements AudioFormatReader.

◆ readMaxLevels()

void AudioSubsectionReader::readMaxLevels ( int64  startSample,
int64  numSamples,
Range< float > *  results,
int  numChannelsToRead 
)
overridevirtual

Finds the highest and lowest sample levels from a section of the audio stream.

This will read a block of samples from the stream, and measure the highest and lowest sample levels from the channels in that section, returning these as normalised floating-point levels.

Parameters
startSamplethe offset into the audio stream to start reading from. It's ok for this to be beyond the start or end of the stream.
numSampleshow many samples to read
resultsthis array will be filled with Range values for each channel. The array must contain numChannels elements.
numChannelsToReadthe number of channels of data to scan. This must be more than zero, but not more than the total number of channels that the reader contains
See also
read

Reimplemented from AudioFormatReader.


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