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pcm/Normalizer: add constant SHIFT

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This commit is contained in:
Max Kellermann 2023-03-13 13:49:01 +01:00
parent de155a740c
commit 1f6637d49a
1 changed files with 11 additions and 10 deletions
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21
src/pcm/Normalizer.cxx
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@ -14,6 +14,7 @@ PcmNormalizer::ProcessS16(int16_t *gcc_restrict dest,
{ {
constexpr SampleFormat format = SampleFormat::S16; constexpr SampleFormat format = SampleFormat::S16;
using Traits = SampleTraits<format>; using Traits = SampleTraits<format>;
constexpr unsigned SHIFT = 10;
int peakVal = 1; int peakVal = 1;
std::size_t peakPos = 0; std::size_t peakPos = 0;
@ -40,25 +41,25 @@ PcmNormalizer::ProcessS16(int16_t *gcc_restrict dest,
} }
//! Determine target gain //! Determine target gain
int newGain = (1 << 10)*target/peakVal; int newGain = (1 << SHIFT)*target/peakVal;
//! Adjust the gain with inertia from the previous gain value //! Adjust the gain with inertia from the previous gain value
int curGain = prev_gain; int curGain = prev_gain;
newGain = (curGain*((1 << smooth) - 1) + newGain) >> smooth; newGain = (curGain*((1 << smooth) - 1) + newGain) >> smooth;
//! Make sure it's no more than the maximum gain value //! Make sure it's no more than the maximum gain value
if (newGain > (maxgain << 10)) if (newGain > (maxgain << SHIFT))
newGain = maxgain << 10; newGain = maxgain << SHIFT;
//! Make sure it's no less than 1:1 //! Make sure it's no less than 1:1
if (newGain < (1 << 10)) if (newGain < (1 << SHIFT))
newGain = 1 << 10; newGain = 1 << SHIFT;
//! Make sure the adjusted gain won't cause clipping //! Make sure the adjusted gain won't cause clipping
std::size_t ramp = src.size(); std::size_t ramp = src.size();
if ((peakVal*newGain >> 10) > Traits::MAX) if ((peakVal*newGain >> SHIFT) > Traits::MAX)
{ {
newGain = (Traits::MAX << 10)/peakVal; newGain = (Traits::MAX << SHIFT)/peakVal;
//! Truncate the ramp time //! Truncate the ramp time
ramp = peakPos; ramp = peakPos;
} }
@ -69,12 +70,12 @@ PcmNormalizer::ProcessS16(int16_t *gcc_restrict dest,
if (!ramp) if (!ramp)
ramp = 1; ramp = 1;
if (!curGain) if (!curGain)
curGain = 1 << 10; curGain = 1 << SHIFT;
const int delta = (newGain - curGain) / (int)ramp; const int delta = (newGain - curGain) / (int)ramp;
for (const auto sample : src.first(ramp)) { for (const auto sample : src.first(ramp)) {
//! Amplify the sample //! Amplify the sample
*dest++ = PcmClamp<format>(sample * curGain >> 10); *dest++ = PcmClamp<format>(sample * curGain >> SHIFT);
//! Adjust the gain //! Adjust the gain
curGain += delta; curGain += delta;
@ -84,6 +85,6 @@ PcmNormalizer::ProcessS16(int16_t *gcc_restrict dest,
for (const auto sample : src.subspan(ramp)) { for (const auto sample : src.subspan(ramp)) {
//! Amplify the sample //! Amplify the sample
*dest++ = PcmClamp<format>(sample * curGain >> 10); *dest++ = PcmClamp<format>(sample * curGain >> SHIFT);
} }
} }