dsp::Convolution Class Reference

Performs stereo uniform-partitioned convolution of an input signal with an impulse response in the frequency domain, using the juce FFT class. More...

Public Member Functions
	Convolution ()
	Initialises an object for performing convolution in the frequency domain. More...
	~Convolution ()
	Destructor. More...
void	prepare (const ProcessSpec &)
	Must be called before loading any impulse response, to provide to the convolution the maximumBufferSize to handle, and the sample rate useful for optional resampling. More...
void	reset () noexcept
	Resets the processing pipeline, ready to start a new stream of data. More...
template<typename ProcessContext >
void	process (const ProcessContext &context) noexcept
	Performs the filter operation on the given set of samples, with optional stereo processing. More...
void	loadImpulseResponse (const void *sourceData, size_t sourceDataSize, bool wantsStereo, bool wantsTrimming, size_t size, bool wantsNormalisation=true)
	This function loads an impulse response audio file from memory, added in a JUCE project with the Projucer as binary data. More...
void	loadImpulseResponse (const File &fileImpulseResponse, bool wantsStereo, bool wantsTrimming, size_t size, bool wantsNormalisation=true)
	This function loads an impulse response from an audio file on any drive. More...
void	copyAndLoadImpulseResponseFromBuffer (AudioBuffer< float > &buffer, double bufferSampleRate, bool wantsStereo, bool wantsTrimming, bool wantsNormalisation, size_t size)
	This function loads an impulse response from an audio buffer, which is copied before doing anything else. More...
void	copyAndLoadImpulseResponseFromBlock (AudioBlock< float > block, double bufferSampleRate, bool wantsStereo, bool wantsTrimming, bool wantsNormalisation, size_t size)
	This function loads an impulse response from an audio block, which is copied before doing anything else. More...

Detailed Description

Performs stereo uniform-partitioned convolution of an input signal with an impulse response in the frequency domain, using the juce FFT class.

It provides some thread-safe functions to load impulse responses as well, from audio files or memory on the fly without any noticeable artefacts, performing resampling and trimming if necessary.

The processing is equivalent to the time domain convolution done in the class FIRFilter, with a FIRFilter::Coefficients object having as coefficients the samples of the impulse response. However, it is more efficient in general to do frequency domain convolution when the size of the impulse response is higher than 64 samples.

See also

FIRFilter, FIRFilter::Coefficients, FFT

Constructor & Destructor Documentation

Convolution()

dsp::Convolution::Convolution

(

)

Initialises an object for performing convolution in the frequency domain.

~Convolution()

dsp::Convolution::~Convolution

(

)

Destructor.

Member Function Documentation

prepare()

void dsp::Convolution::prepare

(

const ProcessSpec &

)

Must be called before loading any impulse response, to provide to the convolution the maximumBufferSize to handle, and the sample rate useful for optional resampling.

reset()

void dsp::Convolution::reset ( )

noexcept

Resets the processing pipeline, ready to start a new stream of data.

process()

template<typename ProcessContext >

void dsp::Convolution::process ( const ProcessContext &  context )

noexcept

Performs the filter operation on the given set of samples, with optional stereo processing.

References dsp::isBypassed(), and JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR.

loadImpulseResponse() [1/2]

void dsp::Convolution::loadImpulseResponse	(	const void *	sourceData,
		size_t	sourceDataSize,
		bool	wantsStereo,
		bool	wantsTrimming,
		size_t	size,
		bool	wantsNormalisation = true
	)

This function loads an impulse response audio file from memory, added in a JUCE project with the Projucer as binary data.

It can load any of the audio formats registered in JUCE, and performs some resampling and pre-processing as well if needed.

Note: Obviously, don't try to use this function on float samples, since the data is supposed to be an audio file in its binary format, and be sure that the original data is not going to move at all its memory location during the process !!

Parameters

sourceData	the block of data to use as the stream's source
sourceDataSize	the number of bytes in the source data block
wantsStereo	requests to process both stereo channels or only one mono channel
wantsTrimming	requests to trim the start and the end of the impulse response
size	the expected size for the impulse response after loading, can be set to 0 for requesting maximum original impulse response size
wantsNormalisation	requests to normalise the impulse response amplitude

loadImpulseResponse() [2/2]

void dsp::Convolution::loadImpulseResponse	(	const File &	fileImpulseResponse,
		bool	wantsStereo,
		bool	wantsTrimming,
		size_t	size,
		bool	wantsNormalisation = true
	)

This function loads an impulse response from an audio file on any drive.

It can load any of the audio formats registered in JUCE, and performs some resampling and pre-processing as well if needed.

Parameters

fileImpulseResponse	the location of the audio file
wantsStereo	requests to process both stereo channels or only one mono channel
wantsTrimming	requests to trim the start and the end of the impulse response
size	the expected size for the impulse response after loading, can be set to 0 for requesting maximum original impulse response size
wantsNormalisation	requests to normalise the impulse response amplitude

copyAndLoadImpulseResponseFromBuffer()

void dsp::Convolution::copyAndLoadImpulseResponseFromBuffer	(	AudioBuffer< float > &	buffer,
		double	bufferSampleRate,
		bool	wantsStereo,
		bool	wantsTrimming,
		bool	wantsNormalisation,
		size_t	size
	)

This function loads an impulse response from an audio buffer, which is copied before doing anything else.

Performs some resampling and pre-processing as well if needed.

Parameters

buffer	the AudioBuffer to use
bufferSampleRate	the sampleRate of the data in the AudioBuffer
wantsStereo	requests to process both stereo channels or only one mono channel
wantsTrimming	requests to trim the start and the end of the impulse response
wantsNormalisation	requests to normalise the impulse response amplitude
size	the expected size for the impulse response after loading, can be set to 0 for requesting maximum original impulse response size

copyAndLoadImpulseResponseFromBlock()

void dsp::Convolution::copyAndLoadImpulseResponseFromBlock	(	AudioBlock< float >	block,
		double	bufferSampleRate,
		bool	wantsStereo,
		bool	wantsTrimming,
		bool	wantsNormalisation,
		size_t	size
	)

This function loads an impulse response from an audio block, which is copied before doing anything else.

Performs some resampling and pre-processing as well if needed.

Parameters

block	the AudioBlock to use
bufferSampleRate	the sampleRate of the data in the AudioBuffer
wantsStereo	requests to process both stereo channels or only one channel
wantsTrimming	requests to trim the start and the end of the impulse response
wantsNormalisation	requests to normalise the impulse response amplitude
size	the expected size for the impulse response after loading, -1 for maximum length

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

• juce_Convolution.h