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Merge pull request #14040 from unknownbrackets/resampler-bias

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Audio: Avoid left shift when resampling
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Henrik Rydgård 2021-02-16 22:53:22 +01:00 • committed by GitHub
commit a911d99ac6
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1 changed files with 6 additions and 4 deletions
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10
Core/HW/StereoResampler.cpp
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@ -161,6 +161,10 @@ void StereoResampler::Clear() {
memset(m_buffer, 0, m_maxBufsize * 2 * sizeof(int16_t));
}
inline int16_t MixSingleSample(int16_t s1, int16_t s2, uint16_t frac) {
return s1 + (((s2 - s1) * frac) >> 16);
}
// Executed from sound stream thread, pulling sound out of the buffer.
unsigned int StereoResampler::Mix(short* samples, unsigned int numSamples, bool consider_framelimit, int sample_rate) {
if (!samples)
@ -222,10 +226,8 @@ unsigned int StereoResampler::Mix(short* samples, unsigned int numSamples, bool
s16 r1 = m_buffer[(indexR + 1) & INDEX_MASK]; //current
s16 l2 = m_buffer[indexR2 & INDEX_MASK]; //next
s16 r2 = m_buffer[(indexR2 + 1) & INDEX_MASK]; //next
int sampleL = ((l1 << 16) + (l2 - l1) * (u16)frac) >> 16;
int sampleR = ((r1 << 16) + (r2 - r1) * (u16)frac) >> 16;
samples[currentSample] = sampleL;
samples[currentSample + 1] = sampleR;
samples[currentSample] = MixSingleSample(l1, l2, (u16)frac);
samples[currentSample + 1] = MixSingleSample(r1, r2, (u16)frac);
frac += ratio;
indexR += 2 * (frac >> 16);
frac &= 0xffff;