Signalsmith-Audio/signalsmith-stretch
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Add .exact() method to process entire buffers, including folding extra output back in

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Geraint 2025-06-14 09:41:05 +01:00
parent 343581bb52
commit c5987267e6
3 changed files with 102 additions and 45 deletions
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26
cmd/Makefile
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@ -11,19 +11,19 @@ out/stretch: main.cpp ../signalsmith-stretch.h util/*.h util/*.hxx
# Uses input files from: https://signalsmith-audio.co.uk/code/stretch/inputs.zip # Uses input files from: https://signalsmith-audio.co.uk/code/stretch/inputs.zip
examples: out/stretch examples: out/stretch
mkdir -p out/examples mkdir -p out/examples
inputs/run-all.sh out/examples/u2- out/stretch --semitones=2 inputs/run-all.sh out/examples/u2- out/stretch --semitones=2 --exact
inputs/run-all.sh out/examples/d2- out/stretch --semitones=-2 inputs/run-all.sh out/examples/d2- out/stretch --semitones=-2 --exact
inputs/run-all.sh out/examples/u4- out/stretch --semitones=4 inputs/run-all.sh out/examples/u4- out/stretch --semitones=4 --exact
inputs/run-all.sh out/examples/d4- out/stretch --semitones=-4 inputs/run-all.sh out/examples/d4- out/stretch --semitones=-4 --exact
inputs/run-all.sh out/examples/u8- out/stretch --semitones=8 inputs/run-all.sh out/examples/u8- out/stretch --semitones=8 --exact
inputs/run-all.sh out/examples/d8- out/stretch --semitones=-8 inputs/run-all.sh out/examples/d8- out/stretch --semitones=-8 --exact
inputs/run-all.sh out/examples/u16- out/stretch --semitones=16 inputs/run-all.sh out/examples/u16- out/stretch --semitones=16 --exact
inputs/run-all.sh out/examples/d16- out/stretch --semitones=-16 inputs/run-all.sh out/examples/d16- out/stretch --semitones=-16 --exact
inputs/run-all.sh out/examples/t_8- out/stretch --time=0.8 inputs/run-all.sh out/examples/t_8- out/stretch --time=0.8 --exact
inputs/run-all.sh out/examples/t1_2- out/stretch --time=1.2 inputs/run-all.sh out/examples/t1_2- out/stretch --time=1.2 --exact
inputs/run-all.sh out/examples/t1_5- out/stretch --time=1.5 inputs/run-all.sh out/examples/t1_5- out/stretch --time=1.5 --exact
inputs/run-all.sh out/examples/t2- out/stretch --time=2 inputs/run-all.sh out/examples/t2- out/stretch --time=2 --exact
inputs/run-all.sh out/examples/t4- out/stretch --time=4 inputs/run-all.sh out/examples/t4- out/stretch --time=4 --exact
TEST_WAV ?= "inputs/voice.wav" TEST_WAV ?= "inputs/voice.wav"

26
cmd/main.cpp
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@ -123,6 +123,14 @@ int main(int argc, char* argv[]) {
std::cout << "\tallocated " << (initMemory.allocBytes/1000) << "kB, freed " << (initMemory.freeBytes/1000) << "kB\n"; std::cout << "\tallocated " << (initMemory.allocBytes/1000) << "kB, freed " << (initMemory.freeBytes/1000) << "kB\n";
} }
signalsmith::MemoryTracker processMemory;
if (exactLength) {
outWav.samples.resize(outputLength*outWav.channels);
stopwatch.start();
processMemory = {};
stretch.exact(inWav, int(inputLength), outWav, int(outputLength));
} else {
// pad the input at the end, since we'll be reading slightly ahead // pad the input at the end, since we'll be reading slightly ahead
size_t paddedInputLength = inputLength + stretch.inputLatency(); size_t paddedInputLength = inputLength + stretch.inputLatency();
inWav.samples.resize(paddedInputLength*inWav.channels); inWav.samples.resize(paddedInputLength*inWav.channels);
@ -131,18 +139,18 @@ int main(int argc, char* argv[]) {
int paddedOutputLength = outputLength + tailSamples; int paddedOutputLength = outputLength + tailSamples;
outWav.samples.resize(paddedOutputLength*outWav.channels); outWav.samples.resize(paddedOutputLength*outWav.channels);
signalsmith::MemoryTracker processMemory;
stopwatch.start(); stopwatch.start();
// The simplest way to deal with input latency (when have access to the audio buffer) is to always be slightly ahead in the input // The simplest way to deal with input latency (when have access to the audio buffer) is to always be slightly ahead in the input
stretch.seek(inWav, stretch.inputLatency(), 1/time); stretch.seek(inWav, stretch.inputLatency(), 1/time);
inWav.offset += stretch.inputLatency(); inWav.offset += stretch.inputLatency();
// Process it all in one call, although it works just the same if we split into smaller blocks // Process it all in one call, although it works just the same if we split into smaller blocks
processMemory = {};
stretch.process(inWav, int(inputLength), outWav, int(outputLength)); stretch.process(inWav, int(inputLength), outWav, int(outputLength));
// Read the last bit of output without giving it any more input // Read the last bit of output without giving it any more input
outWav.offset += outputLength; outWav.offset += outputLength;
stretch.flush(outWav, tailSamples); stretch.flush(outWav, tailSamples);
outWav.offset -= outputLength; outWav.offset -= outputLength;
}
double processSeconds = stopwatch.lap(); double processSeconds = stopwatch.lap();
double processRate = (inWav.length()/inWav.sampleRate)/processSeconds; double processRate = (inWav.length()/inWav.sampleRate)/processSeconds;
@ -154,20 +162,6 @@ int main(int argc, char* argv[]) {
if (processMemory) args.errorExit("allocated during process()"); if (processMemory) args.errorExit("allocated during process()");
} }
if (exactLength) {
// The start has some extra output - we could just trim it, but we might as well fold it back into the output
for (size_t c = 0; c < outWav.channels; ++c) {
for (int i = 0; i < stretch.outputLatency(); ++i) {
double trimmed = outWav[stretch.outputLatency() - 1 - i][c];
outWav[stretch.outputLatency() + i][c] -= trimmed; // reversed in time and negated
}
}
// Skips the output
outWav.offset += stretch.outputLatency();
// the `.flush()` call already handled foldback stuff at the end (since we asked for a shorter `tailSamples`)
}
#ifdef PROFILE_PLOT_CHUNKS #ifdef PROFILE_PLOT_CHUNKS
signalsmith::plot::Figure figure; signalsmith::plot::Figure figure;
auto &plot = figure(0, 0).plot(400, 150); auto &plot = figure(0, 0).plot(400, 150);

63
signalsmith-stretch.h
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@ -402,6 +402,69 @@ struct SignalsmithStretch {
} }
} }
} }
template<class Inputs, class Outputs>
bool exact(Inputs &&inputs, int inputSamples, Outputs &&outputs, int outputSamples) {
if (outputSamples < outputLatency()*2) return false; // too short for this
struct ZeroPaddedInput {
Inputs &inputs;
int offset, length;
struct Channel {
ZeroPaddedInput &zpi;
int channel;
Sample operator[](int i) {
if (zpi.offset + i < zpi.length) return zpi.inputs[channel][zpi.offset + i];
return 0;
}
};
Channel operator[](int c){
return {*this, c};
}
} zpi{inputs, inputLatency(), inputSamples};
seek(inputs, inputLatency(), Sample(inputSamples)/outputSamples); // start positioned on the centre of the input
process(zpi, inputSamples, outputs, outputSamples);
// Fold the first bit of the input back onto itself
for (int c = 0; c < channels; ++c) {
auto &&channel = outputs[c];
for (int i = 0; i < std::min<int>(outputSamples - outputLatency(), outputLatency()); ++i) {
channel[i + outputLatency()] -= channel[outputLatency() - 1 - i];
}
}
// Shuffle everything along to compensate for output latency
for (int c = 0; c < channels; ++c) {
auto &&channel = outputs[c];
for (int i = 0; i < outputSamples - outputLatency(); ++i) {
channel[i] = channel[i + outputLatency()];
}
}
struct OffsetOutput {
Outputs &outputs;
int offset;
struct Channel {
OffsetOutput &oo;
int channel;
decltype(outputs[0][0]) operator[](int i) {
return oo.outputs[channel][oo.offset + i];
}
};
Channel operator[](int c){
return {*this, c};
}
} oo{outputs, outputSamples - outputLatency()};
// Get the final chunk - extra output is already folded back as part of this
flush(oo, outputLatency());
return true;
}
private: private:
bool _splitComputation = false; bool _splitComputation = false;
struct { struct {