Add rubberband time stretch library

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "3rd_party/JUCE"]
  path = 3rd_party/JUCE
  url = https://github.com/juce-framework/JUCE
+[submodule "3rd_party/rubberband"]
+ path = 3rd_party/rubberband
+ url = https://github.com/breakfastquay/rubberband

CMakeLists.txt

@@ -47,6 +47,11 @@ include(CompilerOptions)
 include(CompilerWarnings)
 include(CodeCoverage)
 
+add_library(ta_rubberband)
+add_library(ta::rubberband ALIAS ta_rubberband)
+target_sources(ta_rubberband PRIVATE 3rd_party/rubberband/single/RubberBandSingle.cpp)
+target_include_directories(ta_rubberband PUBLIC 3rd_party/rubberband)
+
 add_subdirectory(3rd_party/JUCE)
 set_directory_properties(PROPERTIES JUCE_COMPANY_COPYRIGHT "SPDX: GPL-3.0-only")
 set_directory_properties(PROPERTIES JUCE_COMPANY_NAME "tobantAudio")
@@ -113,6 +118,7 @@ target_link_libraries(StiggiDJ
  juce::juce_audio_formats
  juce::juce_audio_utils
  PUBLIC
+ ta::rubberband
  juce::juce_recommended_config_flags
  juce::juce_recommended_lto_flags
  juce::juce_recommended_warning_flags

src/DSP/DJPlayer.cpp

@@ -11,11 +11,32 @@ auto DJPlayer::prepareToPlay(int samplesPerBlockExpected, double sampleRate) ->
 {
  _transportSource.prepareToPlay(samplesPerBlockExpected, sampleRate);
  _resampleSource.prepareToPlay(samplesPerBlockExpected, sampleRate);
+
+ _stretcher = std::make_unique<RubberBand::RubberBandStretcher>(
+ sampleRate, 2, RubberBand::RubberBandStretcher::OptionProcessRealTime);
+
+ _stretcherBuffer.setSize(2, samplesPerBlockExpected);
 }
+
 auto DJPlayer::getNextAudioBlock(juce::AudioSourceChannelInfo const& bufferToFill) -> void
 {
- _resampleSource.getNextAudioBlock(bufferToFill);
+ jassert(bufferToFill.buffer->getNumChannels() == 2);
+ jassert(bufferToFill.startSample == 0);
+
+ _stretcher->setTimeRatio(_stretchRatio.load());
+ _stretcherBuffer.setSize(2, bufferToFill.numSamples, false, false, true);
+
+ while (_stretcher->available() < bufferToFill.numSamples)
+ {
+ auto ctx = juce::AudioSourceChannelInfo{_stretcherBuffer};
+ _resampleSource.getNextAudioBlock(ctx);
+ _stretcher->process(ctx.buffer->getArrayOfReadPointers(), ctx.buffer->getNumSamples(), false);
+ }
+
+ // _stretcher->process(bufferToFill.buffer->getArrayOfReadPointers(), bufferToFill.buffer->getNumSamples(), false);
+ _stretcher->retrieve(bufferToFill.buffer->getArrayOfWritePointers(), bufferToFill.buffer->getNumSamples());
 }
+
 auto DJPlayer::releaseResources() -> void
 {
  _transportSource.releaseResources();
@@ -52,7 +73,8 @@ auto DJPlayer::gain(double gain) -> void
 auto DJPlayer::speed(double ratio) -> void
 {
  jassert(juce::isPositiveAndBelow(ratio, 4.0));
- _resampleSource.setResamplingRatio(ratio);
+ // _resampleSource.setResamplingRatio(ratio);
+ _stretchRatio.store(1.0 / ratio);
 }
 
 auto DJPlayer::position(double posInSecs) -> void { _transportSource.setPosition(posInSecs); }

src/DSP/DJPlayer.hpp

@@ -4,6 +4,8 @@
 #include <juce_audio_devices/juce_audio_devices.h>
 #include <juce_audio_formats/juce_audio_formats.h>
 
+#include "rubberband/RubberBandStretcher.h"
+
 namespace ta
 {
 struct LengthAndSamplerate
@@ -60,6 +62,10 @@ struct DJPlayer final : juce::AudioSource
  juce::AudioTransportSource _transportSource;
  juce::ResamplingAudioSource _resampleSource{&_transportSource, false, 2};
 
+ std::unique_ptr<RubberBand::RubberBandStretcher> _stretcher;
+ juce::AudioBuffer<float> _stretcherBuffer;
+ std::atomic<double> _stretchRatio{1.0};
+
  juce::ListenerList<Listener> _listeners;
 };
 } // namespace ta