Performs stereo partitioned convolution of an input signal with an impulse response in the frequency domain, using the JUCE FFT class. More...
#include <juce_Convolution.h>
Classes | |
struct | Latency |
Contains configuration information for a convolution with a fixed latency. More... | |
class | Mixer |
struct | NonUniform |
Contains configuration information for a non-uniform convolution. More... | |
Public Types | |
enum | Normalise { Normalise::no, Normalise::yes } |
enum | Stereo { Stereo::no, Stereo::yes } |
enum | Trim { Trim::no, Trim::yes } |
Public Member Functions | |
Convolution () | |
Initialises an object for performing convolution in the frequency domain. More... | |
Convolution (const Latency &, ConvolutionMessageQueue &) | |
Behaves the same as the constructor taking a single Latency argument, but with a shared background message queue. More... | |
Convolution (const Latency &requiredLatency) | |
Initialises an object for performing convolution with a fixed latency. More... | |
Convolution (const NonUniform &, ConvolutionMessageQueue &) | |
Behaves the same as the constructor taking a single NonUniform argument, but with a shared background message queue. More... | |
Convolution (const NonUniform &requiredHeadSize) | |
Initialises an object for performing convolution in the frequency domain using a non-uniform partitioned algorithm. More... | |
Convolution (ConvolutionMessageQueue &queue) | |
Initialises a convolution engine using a shared background message queue. More... | |
~Convolution () noexcept | |
int | getCurrentIRSize () const |
This function returns the size of the current IR in samples. More... | |
int | getLatency () const |
This function returns the current latency of the process in samples. More... | |
void | loadImpulseResponse (AudioBuffer< float > &&buffer, double bufferSampleRate, Stereo isStereo, Trim requiresTrimming, Normalise requiresNormalisation) |
This function loads an impulse response from an audio buffer. More... | |
void | loadImpulseResponse (const File &fileImpulseResponse, Stereo isStereo, Trim requiresTrimming, size_t size, Normalise requiresNormalisation=Normalise::yes) |
This function loads an impulse response from an audio file. More... | |
void | loadImpulseResponse (const void *sourceData, size_t sourceDataSize, Stereo isStereo, Trim requiresTrimming, size_t size, Normalise requiresNormalisation=Normalise::yes) |
This function loads an impulse response audio file from memory, added in a JUCE project with the Projucer as binary data. More... | |
void | prepare (const ProcessSpec &) |
Must be called before first calling process. More... | |
template<typename ProcessContext , std::enable_if_t< std::is_same< typename ProcessContext::SampleType, float >::value, int > = 0> | |
void | process (const ProcessContext &context) noexcept |
Performs the filter operation on the given set of samples with optional stereo processing. More... | |
void | reset () noexcept |
Resets the processing pipeline ready to start a new stream of data. More... | |
Private Member Functions | |
Convolution (const Latency &, const NonUniform &, OptionalScopedPointer< ConvolutionMessageQueue > &&) | |
void | processSamples (const AudioBlock< const float > &, AudioBlock< float > &, bool isBypassed) noexcept |
Private Attributes | |
bool | isActive = false |
Mixer | mixer |
std::unique_ptr< Impl > | pimpl |
Performs stereo partitioned convolution of an input signal with an impulse response in the frequency domain, using the JUCE FFT class.
This class provides some thread-safe functions to load impulse responses from audio files or memory on-the-fly without noticeable artefacts, performing resampling and trimming if necessary.
The processing performed by this class is equivalent to the time domain convolution done in the FIRFilter class, with a FIRFilter::Coefficients object having the samples of the impulse response as its coefficients. However, in general it is more efficient to do frequency domain convolution when the size of the impulse response is 64 samples or greater.
Note: The default operation of this class uses zero latency and a uniform partitioned algorithm. If the impulse response size is large, or if the algorithm is too CPU intensive, it is possible to use either a fixed latency version of the algorithm, or a simple non-uniform partitioned convolution algorithm.
Threading: It is not safe to interleave calls to the methods of this class. If you need to load new impulse responses during processing the load() calls must be synchronised with process() calls, which in practice means making the load() call from the audio thread. The loadImpulseResponse() functions are wait-free and are therefore suitable for use in a realtime context.
@tags{DSP}
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juce::dsp::Convolution::Convolution | ( | ) |
Initialises an object for performing convolution in the frequency domain.
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explicit |
Initialises a convolution engine using a shared background message queue.
IMPORTANT: the queue must remain alive throughout the lifetime of the Convolution.
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explicit |
Initialises an object for performing convolution with a fixed latency.
If the requested latency is zero, the actual latency will also be zero. For requested latencies greater than zero, the actual latency will always at least as large as the requested latency. Using a fixed non-zero latency can reduce the CPU consumption of the convolution algorithm.
requiredLatency | the minimum latency |
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explicit |
Initialises an object for performing convolution in the frequency domain using a non-uniform partitioned algorithm.
A requiredHeadSize of 256 samples or greater will improve the efficiency of the processing for IR sizes of 4096 samples or greater (recommended for reverberation IRs).
requiredHeadSize | the head IR size for two stage non-uniform partitioned convolution |
juce::dsp::Convolution::Convolution | ( | const Latency & | , |
ConvolutionMessageQueue & | |||
) |
Behaves the same as the constructor taking a single Latency argument, but with a shared background message queue.
IMPORTANT: the queue must remain alive throughout the lifetime of the Convolution.
juce::dsp::Convolution::Convolution | ( | const NonUniform & | , |
ConvolutionMessageQueue & | |||
) |
Behaves the same as the constructor taking a single NonUniform argument, but with a shared background message queue.
IMPORTANT: the queue must remain alive throughout the lifetime of the Convolution.
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noexcept |
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int juce::dsp::Convolution::getCurrentIRSize | ( | ) | const |
This function returns the size of the current IR in samples.
int juce::dsp::Convolution::getLatency | ( | ) | const |
This function returns the current latency of the process in samples.
Note: This is the latency of the convolution engine, not the latency associated with the current impulse response choice that has to be considered separately (linear phase filters, for example).
void juce::dsp::Convolution::loadImpulseResponse | ( | AudioBuffer< float > && | buffer, |
double | bufferSampleRate, | ||
Stereo | isStereo, | ||
Trim | requiresTrimming, | ||
Normalise | requiresNormalisation | ||
) |
This function loads an impulse response from an audio buffer.
To avoid memory allocation on the audio thread, this function takes ownership of the buffer passed in.
If calling this function during processing, make sure that the buffer is not allocated on the audio thread (be careful of accidental copies!). If you need to pass arbitrary/generated buffers it's recommended to create these buffers on a separate thread and to use some wait-free construct (a lock-free queue or a SpinLock/GenericScopedTryLock combination) to transfer ownership to the audio thread without allocating.
buffer | the AudioBuffer to use |
bufferSampleRate | the sampleRate of the data in the AudioBuffer |
isStereo | selects either stereo or mono |
requiresTrimming | optionally trim the start and the end of the impulse response |
requiresNormalisation | optionally normalise the impulse response amplitude |
void juce::dsp::Convolution::loadImpulseResponse | ( | const File & | fileImpulseResponse, |
Stereo | isStereo, | ||
Trim | requiresTrimming, | ||
size_t | size, | ||
Normalise | requiresNormalisation = Normalise::yes |
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This function loads an impulse response from an audio file.
It can load any of the audio formats registered in JUCE, and performs some resampling and pre-processing as well if needed.
fileImpulseResponse | the location of the audio file |
isStereo | selects either stereo or mono |
requiresTrimming | optionally 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 to requesting the original impulse response size |
requiresNormalisation | optionally normalise the impulse response amplitude |
void juce::dsp::Convolution::loadImpulseResponse | ( | const void * | sourceData, |
size_t | sourceDataSize, | ||
Stereo | isStereo, | ||
Trim | requiresTrimming, | ||
size_t | size, | ||
Normalise | requiresNormalisation = Normalise::yes |
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) |
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: Don't try to use this function on float samples, since the data is expected to be an audio file in its binary format. Be sure that the original data remains constant throughout the lifetime of the Convolution object, as the loading process will happen on a background thread once this function has returned.
sourceData | the block of data to use as the stream's source |
sourceDataSize | the number of bytes in the source data block |
isStereo | selects either stereo or mono |
requiresTrimming | optionally 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 to requesting the original impulse response size |
requiresNormalisation | optionally normalise the impulse response amplitude |
void juce::dsp::Convolution::prepare | ( | const ProcessSpec & | ) |
Must be called before first calling process.
In general, calls to loadImpulseResponse() load the impulse response (IR) asynchronously. The IR will become active once it has been completely loaded and processed, which may take some time.
Calling prepare() will ensure that the IR supplied to the most recent call to loadImpulseResponse() is fully initialised. This IR will then be active during the next call to process(). It is recommended to call loadImpulseResponse() before prepare() if a specific IR must be active during the first process() call.
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inlinenoexcept |
Performs the filter operation on the given set of samples with optional stereo processing.
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privatenoexcept |
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noexcept |
Resets the processing pipeline ready to start a new stream of data.
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