JUCE: AudioFormatWriter Class Reference

JUCE

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AudioFormatWriter Class Referenceabstract

Writes samples to an audio file stream. More...

## Classes
class | ThreadedWriter
| Provides a FIFO for an AudioFormatWriter, allowing you to push incoming data into a buffer which will be flushed to disk by a background thread. More...
struct | WriteHelper
| Used by AudioFormatWriter subclasses to copy data to different formats. More...

## Public Member Functions
virtual | ~AudioFormatWriter ()
| Destructor. More...
const String & | getFormatName () const noexcept
| Returns a description of what type of format this is. More...
virtual bool | write (const int **samplesToWrite, int numSamples)=0
| Writes a set of samples to the audio stream. More...
virtual bool | flush ()
| Some formats may support a flush operation that makes sure the file is in a valid state before carrying on. More...
bool | writeFromAudioReader (AudioFormatReader &reader, int64 startSample, int64 numSamplesToRead)
| Reads a section of samples from an AudioFormatReader, and writes these to the output. More...
bool | writeFromAudioSource (AudioSource &source, int numSamplesToRead, int samplesPerBlock=2048)
| Reads some samples from an AudioSource, and writes these to the output. More...
bool | writeFromAudioSampleBuffer (const AudioBuffer< float > &source, int startSample, int numSamples)
| Writes some samples from an AudioBuffer. More...
bool | writeFromFloatArrays (const float *const *channels, int numChannels, int numSamples)
| Writes some samples from a set of float data channels. More...
double | getSampleRate () const noexcept
| Returns the sample rate being used. More...
int | getNumChannels () const noexcept
| Returns the number of channels being written. More...
int | getBitsPerSample () const noexcept
| Returns the bit-depth of the data being written. More...
bool | isFloatingPoint () const noexcept
| Returns true if it's a floating-point format, false if it's fixed-point. More...

## Protected Member Functions
| AudioFormatWriter (OutputStream *destStream, const String &formatName, double sampleRate, unsigned int numberOfChannels, unsigned int bitsPerSample)
| Creates an AudioFormatWriter object. More...
| AudioFormatWriter (OutputStream *destStream, const String &formatName, double sampleRate, const AudioChannelSet &audioChannelLayout, unsigned int bitsPerSample)
| Creates an AudioFormatWriter object. More...

## Protected Attributes
double | sampleRate
| The sample rate of the stream. More...
unsigned int | numChannels
| The number of channels being written to the stream. More...
unsigned int | bitsPerSample
| The bit depth of the file. More...
bool | usesFloatingPointData
| True if it's a floating-point format, false if it's fixed-point. More...
AudioChannelSet | channelLayout
| The audio channel layout that the writer should use. More...
OutputStream * | output
| The output stream for use by subclasses. More...

## Detailed Description

Writes samples to an audio file stream.

A subclass that writes a specific type of audio format will be created by an AudioFormat object.

After creating one of these with the AudioFormat::createWriterFor() method you can call its write() method to store the samples, and then delete it.

See also
  AudioFormat, AudioFormatReader

## Constructor & Destructor Documentation

## ◆ AudioFormatWriter() [1/2]

AudioFormatWriter::AudioFormatWriter | ( | OutputStream * | destStream,
|  | const String & | formatName,
|  | double | sampleRate,
|  | unsigned int | numberOfChannels,
|  | unsigned int | bitsPerSample
| ) |  |
| protected

Creates an AudioFormatWriter object.

Parameters

  destStream | the stream to write to - this will be deleted by this object when it is no longer needed
  formatName | the description that will be returned by the getFormatName() method
  sampleRate | the sample rate to use - the base class just stores this value, it doesn't do anything with it
  numberOfChannels | the number of channels to write - the base class just stores this value, it doesn't do anything with it
  bitsPerSample | the bit depth of the stream - the base class just stores this value, it doesn't do anything with it

## ◆ AudioFormatWriter() [2/2]

AudioFormatWriter::AudioFormatWriter | ( | OutputStream * | destStream,
|  | const String & | formatName,
|  | double | sampleRate,
|  | const AudioChannelSet & | audioChannelLayout,
|  | unsigned int | bitsPerSample
| ) |  |
| protected

Creates an AudioFormatWriter object.

Parameters

  destStream | the stream to write to - this will be deleted by this object when it is no longer needed
  formatName | the description that will be returned by the getFormatName() method
  sampleRate | the sample rate to use - the base class just stores this value, it doesn't do anything with it
  audioChannelLayout | the channel layout to use for the writer - the base class just stores this value, it doesn't do anything with it
  bitsPerSample | the bit depth of the stream - the base class just stores this value, it doesn't do anything with it

## ◆ ~AudioFormatWriter()

virtual AudioFormatWriter::~AudioFormatWriter | ( |  | ) |
| virtual

Destructor.

## Member Function Documentation

## ◆ getFormatName()

const String& AudioFormatWriter::getFormatName | ( |  | ) | const
| noexcept

Returns a description of what type of format this is.

E.g. "AIFF file"

## ◆ write()

virtual bool AudioFormatWriter::write | ( | const int ** | samplesToWrite,
|  | int | numSamples
| ) |  |
| pure virtual

Writes a set of samples to the audio stream.

Note that if you're trying to write the contents of an AudioBuffer, you can use writeFromAudioSampleBuffer().

Parameters

  samplesToWrite | an array of arrays containing the sample data for each channel to write. This is a zero-terminated array of arrays, and can contain a different number of channels than the actual stream uses, and the writer should do its best to cope with this. If the format is fixed-point, each channel will be formatted as an array of signed integers using the full 32-bit range -0x80000000 to 0x7fffffff, regardless of the source's bit-depth. If it is a floating-point format, you should treat the arrays as arrays of floats, and just cast it to an (int**) to pass it into the method.
  numSamples | the number of samples to write

## ◆ flush()

virtual bool AudioFormatWriter::flush | ( |  | ) |
| virtual

Some formats may support a flush operation that makes sure the file is in a valid state before carrying on.

If supported, this means that by calling flush periodically when writing data to a large file, then it should still be left in a readable state if your program crashes. It goes without saying that this method must be called from the same thread that's calling write()! If the format supports flushing and the operation succeeds, this returns true.

## ◆ writeFromAudioReader()

bool AudioFormatWriter::writeFromAudioReader | ( | AudioFormatReader & | reader,
|  | int64 | startSample,
|  | int64 | numSamplesToRead
| ) |  |

Reads a section of samples from an AudioFormatReader, and writes these to the output.

This will take care of any floating-point conversion that's required to convert between the two formats. It won't deal with sample-rate conversion, though.

If numSamplesToRead < 0, it will write the entire length of the reader.

Returns
  false if it can't read or write properly during the operation

## ◆ writeFromAudioSource()

bool AudioFormatWriter::writeFromAudioSource | ( | AudioSource & | source,
|  | int | numSamplesToRead,
|  | int | samplesPerBlock = `2048`
| ) |  |

Reads some samples from an AudioSource, and writes these to the output.

The source must already have been initialised with the AudioSource::prepareToPlay() method

Parameters

  source | the source to read from
  numSamplesToRead | total number of samples to read and write
  samplesPerBlock | the maximum number of samples to fetch from the source

Returns
  false if it can't read or write properly during the operation

## ◆ writeFromAudioSampleBuffer()

bool AudioFormatWriter::writeFromAudioSampleBuffer | ( | const AudioBuffer< float > & | source,
|  | int | startSample,
|  | int | numSamples
| ) |  |

Writes some samples from an AudioBuffer.

## ◆ writeFromFloatArrays()

bool AudioFormatWriter::writeFromFloatArrays | ( | const float *const * | channels,
|  | int | numChannels,
|  | int | numSamples
| ) |  |

Writes some samples from a set of float data channels.

## ◆ getSampleRate()

double AudioFormatWriter::getSampleRate | ( |  | ) | const
| noexcept

Returns the sample rate being used.

## ◆ getNumChannels()

int AudioFormatWriter::getNumChannels | ( |  | ) | const
| noexcept

Returns the number of channels being written.

## ◆ getBitsPerSample()

int AudioFormatWriter::getBitsPerSample | ( |  | ) | const
| noexcept

Returns the bit-depth of the data being written.

## ◆ isFloatingPoint()

bool AudioFormatWriter::isFloatingPoint | ( |  | ) | const
| noexcept

Returns true if it's a floating-point format, false if it's fixed-point.

## Member Data Documentation

## ◆ sampleRate

double AudioFormatWriter::sampleRate
| protected

The sample rate of the stream.

## ◆ numChannels

unsigned int AudioFormatWriter::numChannels
| protected

The number of channels being written to the stream.

## ◆ bitsPerSample

unsigned int AudioFormatWriter::bitsPerSample
| protected

The bit depth of the file.

## ◆ usesFloatingPointData

bool AudioFormatWriter::usesFloatingPointData
| protected

True if it's a floating-point format, false if it's fixed-point.

## ◆ channelLayout

AudioChannelSet AudioFormatWriter::channelLayout
| protected

The audio channel layout that the writer should use.

## ◆ output

OutputStream* AudioFormatWriter::output
| protected

The output stream for use by subclasses.

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

- juce_AudioFormatWriter.h