diff options
| author | Chris Robinson <chris.kcat@gmail.com> | 2020-11-09 12:32:26 -0800 |
|---|---|---|
| committer | Chris Robinson <chris.kcat@gmail.com> | 2020-11-09 12:33:07 -0800 |
| commit | 7e76770278688a0ff9d65405cb98ee0d22462476 (patch) | |
| tree | 0c4e62b7cb704ec9c8b12fbea5254c00c77c352d | |
| parent | 3a58bac7bd4e0baa2a24169703c8cb7e6fc49e8f (diff) | |
Avoid an unnecessary multiplier
| -rw-r--r-- | alc/effects/pshifter.cpp | 27 |
1 files changed, 12 insertions, 15 deletions
diff --git a/alc/effects/pshifter.cpp b/alc/effects/pshifter.cpp index e9d188d3..84a001d1 100644 --- a/alc/effects/pshifter.cpp +++ b/alc/effects/pshifter.cpp @@ -67,7 +67,7 @@ alignas(16) const std::array<double,STFT_SIZE> HannWindow = InitHannWindow(); struct FrequencyBin { double Amplitude; - double Frequency; + double FreqBin; }; @@ -76,7 +76,6 @@ struct PshifterState final : public EffectState { size_t mCount; ALuint mPitchShiftI; double mPitchShift; - double mFreqPerBin; /* Effects buffers */ std::array<double,STFT_SIZE> mFIFO; @@ -105,13 +104,12 @@ struct PshifterState final : public EffectState { DEF_NEWDEL(PshifterState) }; -void PshifterState::deviceUpdate(const ALCdevice *device) +void PshifterState::deviceUpdate(const ALCdevice* /*device*/) { /* (Re-)initializing parameters and clear the buffers. */ mCount = FIFO_LATENCY; mPitchShiftI = MixerFracOne; mPitchShift = 1.0; - mFreqPerBin = device->Frequency / double{STFT_SIZE}; std::fill(mFIFO.begin(), mFIFO.end(), 0.0); std::fill(mLastPhase.begin(), mLastPhase.end(), 0.0); @@ -145,8 +143,10 @@ void PshifterState::process(const size_t samplesToDo, const al::span<const Float * http://blogs.zynaptiq.com/bernsee/pitch-shifting-using-the-ft/ */ - static constexpr double expected{al::MathDefs<double>::Tau() / OVERSAMP}; - const double freq_per_bin{mFreqPerBin}; + /* Cycle offset per update expected of each frequency bin (bin 0 is none, + * bin 1 is x1, bin 2 is x2, etc). + */ + constexpr double expected_cycles{al::MathDefs<double>::Tau() / OVERSAMP}; for(size_t base{0u};base < samplesToDo;) { @@ -183,20 +183,20 @@ void PshifterState::process(const size_t samplesToDo, const al::span<const Float const double phase{std::arg(mFftBuffer[k])}; /* Compute phase difference and subtract expected phase difference */ - double tmp{(phase - mLastPhase[k]) - static_cast<double>(k)*expected}; + double tmp{(phase - mLastPhase[k]) - static_cast<double>(k)*expected_cycles}; /* Map delta phase into +/- Pi interval */ int qpd{double2int(tmp / al::MathDefs<double>::Pi())}; tmp -= al::MathDefs<double>::Pi() * (qpd + (qpd%2)); /* Get deviation from bin frequency from the +/- Pi interval */ - tmp /= expected; + tmp /= expected_cycles; /* Compute the k-th partials' true frequency and store the - * amplitude and true frequency in the analysis buffer. + * amplitude and frequency bin in the analysis buffer. */ mAnalysisBuffer[k].Amplitude = amplitude; - mAnalysisBuffer[k].Frequency = (static_cast<double>(k) + tmp) * freq_per_bin; + mAnalysisBuffer[k].FreqBin = static_cast<double>(k) + tmp; /* Store the actual phase[k] for the next frame. */ mLastPhase[k] = phase; @@ -212,7 +212,7 @@ void PshifterState::process(const size_t samplesToDo, const al::span<const Float { const size_t j{(k*mPitchShiftI + (MixerFracOne>>1)) >> MixerFracBits}; mSynthesisBuffer[j].Amplitude += mAnalysisBuffer[k].Amplitude; - mSynthesisBuffer[j].Frequency = mAnalysisBuffer[k].Frequency * mPitchShift; + mSynthesisBuffer[j].FreqBin = mAnalysisBuffer[k].FreqBin * mPitchShift; } /* Reconstruct the frequency-domain signal from the adjusted frequency @@ -220,11 +220,8 @@ void PshifterState::process(const size_t samplesToDo, const al::span<const Float */ for(size_t k{0u};k < STFT_HALF_SIZE+1;k++) { - /* Compute bin deviation from scaled freq */ - const double tmp{mSynthesisBuffer[k].Frequency / freq_per_bin}; - /* Calculate actual delta phase and accumulate it to get bin phase */ - mSumPhase[k] += tmp * expected; + mSumPhase[k] += mSynthesisBuffer[k].FreqBin * expected_cycles; mFftBuffer[k] = std::polar(mSynthesisBuffer[k].Amplitude, mSumPhase[k]); } |