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Fix playback within Sample (#7100)
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This revisits two main aspects of playback from `Sample`: copying frames into a temporary playback buffer before resampling, and advancing the state's frame index.  Both operations were improperly done, causing distorted audio to be heard when resampling from within the `Sample::play` function.

To fix this, playback into the temporary playback buffer is now done using the `playRaw` function, which copies the frame one by one in a loop, moving through the buffer correctly as determined by the loop mode. In addition, advancement of the playback index is done using the `advance` function, which advances the index by the given amount and handles an out of bounds index for the loop modes as necessary using the modulo operator.
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@sakertooth
sakertooth authored Feb 16, 2024
1 parent c87ff41 commit a81ad74
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Showing 4 changed files with 101 additions and 89 deletions.
21 changes: 8 additions & 13 deletions include/Sample.h
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Original file line number Diff line number Diff line change
Expand Up @@ -33,9 +33,6 @@
#include "SampleBuffer.h"
#include "lmms_export.h"

class QPainter;
class QRect;

namespace lmms {
class LMMS_EXPORT Sample
{
Expand Down Expand Up @@ -63,25 +60,25 @@ class LMMS_EXPORT Sample
}

auto resampler() -> AudioResampler& { return m_resampler; }
auto frameIndex() const -> f_cnt_t { return m_frameIndex; }
auto frameIndex() const -> int { return m_frameIndex; }
auto varyingPitch() const -> bool { return m_varyingPitch; }
auto backwards() const -> bool { return m_backwards; }

void setFrameIndex(f_cnt_t frameIndex) { m_frameIndex = frameIndex; }
void setFrameIndex(int frameIndex) { m_frameIndex = frameIndex; }
void setVaryingPitch(bool varyingPitch) { m_varyingPitch = varyingPitch; }
void setBackwards(bool backwards) { m_backwards = backwards; }

private:
AudioResampler m_resampler;
f_cnt_t m_frameIndex = 0;
int m_frameIndex = 0;
bool m_varyingPitch = false;
bool m_backwards = false;
friend class Sample;
};

Sample() = default;
Sample(const QByteArray& base64, int sampleRate = Engine::audioEngine()->processingSampleRate());
Sample(const sampleFrame* data, int numFrames, int sampleRate = Engine::audioEngine()->processingSampleRate());
Sample(const sampleFrame* data, size_t numFrames, int sampleRate = Engine::audioEngine()->processingSampleRate());
Sample(const Sample& other);
Sample(Sample&& other);
explicit Sample(const QString& audioFile);
Expand All @@ -90,8 +87,8 @@ class LMMS_EXPORT Sample
auto operator=(const Sample&) -> Sample&;
auto operator=(Sample&&) -> Sample&;

auto play(sampleFrame* dst, PlaybackState* state, int numFrames, float desiredFrequency = DefaultBaseFreq,
Loop loopMode = Loop::Off) -> bool;
auto play(sampleFrame* dst, PlaybackState* state, size_t numFrames, float desiredFrequency = DefaultBaseFreq,
Loop loopMode = Loop::Off) const -> bool;

auto sampleDuration() const -> std::chrono::milliseconds;
auto sampleFile() const -> const QString& { return m_buffer->audioFile(); }
Expand Down Expand Up @@ -120,10 +117,8 @@ class LMMS_EXPORT Sample
void setReversed(bool reversed) { m_reversed.store(reversed, std::memory_order_relaxed); }

private:
void playSampleRange(PlaybackState* state, sampleFrame* dst, size_t numFrames) const;
void amplifySampleRange(sampleFrame* src, int numFrames) const;
void copyBufferForward(sampleFrame* dst, int initialPosition, int advanceAmount) const;
void copyBufferBackward(sampleFrame* dst, int initialPosition, int advanceAmount) const;
void playRaw(sampleFrame* dst, size_t numFrames, const PlaybackState* state, Loop loopMode) const;
void advance(PlaybackState* state, size_t advanceAmount, Loop loopMode) const;

private:
std::shared_ptr<const SampleBuffer> m_buffer = SampleBuffer::emptyBuffer();
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2 changes: 1 addition & 1 deletion include/SampleBuffer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,7 @@ class LMMS_EXPORT SampleBuffer
SampleBuffer(const QString& base64, int sampleRate);
SampleBuffer(std::vector<sampleFrame> data, int sampleRate);
SampleBuffer(
const sampleFrame* data, int numFrames, int sampleRate = Engine::audioEngine()->processingSampleRate());
const sampleFrame* data, size_t numFrames, int sampleRate = Engine::audioEngine()->processingSampleRate());

friend void swap(SampleBuffer& first, SampleBuffer& second) noexcept;
auto toBase64() const -> QString;
Expand Down
165 changes: 91 additions & 74 deletions src/core/Sample.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,7 @@

#include "Sample.h"

#include <QPainter>
#include <QRect>
#include <cassert>

namespace lmms {

Expand All @@ -47,7 +46,7 @@ Sample::Sample(const QByteArray& base64, int sampleRate)
{
}

Sample::Sample(const sampleFrame* data, int numFrames, int sampleRate)
Sample::Sample(const sampleFrame* data, size_t numFrames, int sampleRate)
: m_buffer(std::make_shared<SampleBuffer>(data, numFrames, sampleRate))
, m_startFrame(0)
, m_endFrame(m_buffer->size())
Expand Down Expand Up @@ -117,58 +116,40 @@ auto Sample::operator=(Sample&& other) -> Sample&
return *this;
}

bool Sample::play(sampleFrame* dst, PlaybackState* state, int numFrames, float desiredFrequency, Loop loopMode)
bool Sample::play(sampleFrame* dst, PlaybackState* state, size_t numFrames, float desiredFrequency, Loop loopMode) const
{
if (numFrames <= 0 || desiredFrequency <= 0) { return false; }
assert(numFrames > 0);
assert(desiredFrequency > 0);

auto resampleRatio = static_cast<float>(Engine::audioEngine()->processingSampleRate()) / m_buffer->sampleRate();
resampleRatio *= frequency() / desiredFrequency;
const auto pastBounds = state->m_frameIndex >= m_endFrame || (state->m_frameIndex < 0 && state->m_backwards);
if (loopMode == Loop::Off && pastBounds) { return false; }

auto playBuffer = std::vector<sampleFrame>(numFrames / resampleRatio);
if (!typeInfo<float>::isEqual(resampleRatio, 1.0f))
{
playBuffer.resize(playBuffer.size() + s_interpolationMargins[state->resampler().interpolationMode()]);
}
const auto outputSampleRate = Engine::audioEngine()->processingSampleRate() * m_frequency / desiredFrequency;
const auto inputSampleRate = m_buffer->sampleRate();
const auto resampleRatio = outputSampleRate / inputSampleRate;
const auto marginSize = s_interpolationMargins[state->resampler().interpolationMode()];

const auto start = startFrame();
const auto end = endFrame();
const auto loopStart = loopStartFrame();
const auto loopEnd = loopEndFrame();
state->m_frameIndex = std::max<int>(m_startFrame, state->m_frameIndex);

switch (loopMode)
auto playBuffer = std::vector<sampleFrame>(numFrames / resampleRatio + marginSize);
playRaw(playBuffer.data(), playBuffer.size(), state, loopMode);

const auto resampleResult
= state->resampler().resample(&playBuffer[0][0], playBuffer.size(), &dst[0][0], numFrames, resampleRatio);
advance(state, resampleResult.inputFramesUsed, loopMode);

const auto outputFrames = resampleResult.outputFramesGenerated;
if (outputFrames < numFrames) { std::fill_n(dst + outputFrames, numFrames - outputFrames, sampleFrame{}); }

if (!typeInfo<float>::isEqual(m_amplification, 1.0f))
{
case Loop::Off:
state->m_frameIndex = std::clamp(state->m_frameIndex, start, end);
if (state->m_frameIndex == end) { return false; }
break;
case Loop::On:
state->m_frameIndex = std::clamp(state->m_frameIndex, start, loopEnd);
if (state->m_frameIndex == loopEnd) { state->m_frameIndex = loopStart; }
break;
case Loop::PingPong:
state->m_frameIndex = std::clamp(state->m_frameIndex, start, loopEnd);
if (state->m_frameIndex == loopEnd)
{
state->m_frameIndex = loopEnd - 1;
state->m_backwards = true;
}
else if (state->m_frameIndex <= loopStart && state->m_backwards)
for (int i = 0; i < numFrames; ++i)
{
state->m_frameIndex = loopStart;
state->m_backwards = false;
dst[i][0] *= m_amplification;
dst[i][1] *= m_amplification;
}
break;
}

playSampleRange(state, playBuffer.data(), playBuffer.size());

const auto result
= state->resampler().resample(&playBuffer[0][0], playBuffer.size(), &dst[0][0], numFrames, resampleRatio);
if (result.error != 0) { return false; }

state->m_frameIndex += (state->m_backwards ? -1 : 1) * result.inputFramesUsed;
amplifySampleRange(dst, result.outputFramesGenerated);

return true;
}

Expand All @@ -187,44 +168,80 @@ void Sample::setAllPointFrames(int startFrame, int endFrame, int loopStartFrame,
setLoopEndFrame(loopEndFrame);
}

void Sample::playSampleRange(PlaybackState* state, sampleFrame* dst, size_t numFrames) const
void Sample::playRaw(sampleFrame* dst, size_t numFrames, const PlaybackState* state, Loop loopMode) const
{
auto framesToCopy = 0;
if (state->m_backwards)
{
framesToCopy = std::min<int>(state->m_frameIndex - startFrame(), numFrames);
copyBufferBackward(dst, state->m_frameIndex, framesToCopy);
}
else
auto index = state->m_frameIndex;
auto backwards = state->m_backwards;

for (size_t i = 0; i < numFrames; ++i)
{
framesToCopy = std::min<int>(endFrame() - state->m_frameIndex, numFrames);
copyBufferForward(dst, state->m_frameIndex, framesToCopy);
}
switch (loopMode)
{
case Loop::Off:
if (index < 0 || index > m_endFrame) { return; }
break;
case Loop::On:
if (index < m_loopStartFrame && backwards) { index = m_loopEndFrame - 1; }
else if (index >= m_loopEndFrame) { index = m_loopStartFrame; }
break;
case Loop::PingPong:
if (index < m_loopStartFrame && backwards)
{
index = m_loopStartFrame;
backwards = false;
}
else if (index >= m_loopEndFrame)
{
index = m_loopEndFrame - 1;
backwards = true;
}
break;
default:
break;
}

if (framesToCopy < numFrames) { std::fill_n(dst + framesToCopy, numFrames - framesToCopy, sampleFrame{0, 0}); }
dst[i] = m_buffer->data()[m_reversed ? m_buffer->size() - index - 1 : index];
backwards ? --index : ++index;
}
}

void Sample::copyBufferForward(sampleFrame* dst, int initialPosition, int advanceAmount) const
void Sample::advance(PlaybackState* state, size_t advanceAmount, Loop loopMode) const
{
reversed() ? std::copy_n(m_buffer->rbegin() + initialPosition, advanceAmount, dst)
: std::copy_n(m_buffer->begin() + initialPosition, advanceAmount, dst);
}
state->m_frameIndex += (state->m_backwards ? -1 : 1) * advanceAmount;
if (loopMode == Loop::Off) { return; }

void Sample::copyBufferBackward(sampleFrame* dst, int initialPosition, int advanceAmount) const
{
reversed() ? std::reverse_copy(
m_buffer->rbegin() + initialPosition - advanceAmount, m_buffer->rbegin() + initialPosition, dst)
: std::reverse_copy(
m_buffer->begin() + initialPosition - advanceAmount, m_buffer->begin() + initialPosition, dst);
}
const auto distanceFromLoopStart = std::abs(state->m_frameIndex - m_loopStartFrame);
const auto distanceFromLoopEnd = std::abs(state->m_frameIndex - m_loopEndFrame);
const auto loopSize = m_loopEndFrame - m_loopStartFrame;
if (loopSize == 0) { return; }

void Sample::amplifySampleRange(sampleFrame* src, int numFrames) const
{
const auto amplification = m_amplification.load(std::memory_order_relaxed);
for (int i = 0; i < numFrames; ++i)
switch (loopMode)
{
src[i][0] *= amplification;
src[i][1] *= amplification;
case Loop::On:
if (state->m_frameIndex < m_loopStartFrame && state->m_backwards)
{
state->m_frameIndex = m_loopEndFrame - 1 - distanceFromLoopStart % loopSize;
}
else if (state->m_frameIndex >= m_loopEndFrame)
{
state->m_frameIndex = m_loopStartFrame + distanceFromLoopEnd % loopSize;
}
break;
case Loop::PingPong:
if (state->m_frameIndex < m_loopStartFrame && state->m_backwards)
{
state->m_frameIndex = m_loopStartFrame + distanceFromLoopStart % loopSize;
state->m_backwards = false;
}
else if (state->m_frameIndex >= m_loopEndFrame)
{
state->m_frameIndex = m_loopEndFrame - 1 - distanceFromLoopEnd % loopSize;
state->m_backwards = true;
}
break;
default:
break;
}
}

} // namespace lmms
2 changes: 1 addition & 1 deletion src/core/SampleBuffer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@

namespace lmms {

SampleBuffer::SampleBuffer(const sampleFrame* data, int numFrames, int sampleRate)
SampleBuffer::SampleBuffer(const sampleFrame* data, size_t numFrames, int sampleRate)
: m_data(data, data + numFrames)
, m_sampleRate(sampleRate)
{
Expand Down

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