2b10cf3c15
"LGPL-2.1" doesn't exist, and the old copyright header did not specify the "or later" clause, so I must assume it's 2.1 only.
103 lines
2.5 KiB
C++
103 lines
2.5 KiB
C++
// SPDX-License-Identifier: LGPL-2.1-only
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// Copyright The Music Player Daemon Project
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// Based on AudioCompress (c)2007 busybee (http://beesbuzz.biz/
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#include "Normalizer.hxx"
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#include "Clamp.hxx"
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#include "SampleFormat.hxx"
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#include "Traits.hxx"
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#include "util/Compiler.h"
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#include <algorithm> // for std::fill_n()
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void
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PcmNormalizer::Reset() noexcept
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{
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prev_gain = 0;
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pos = 0;
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std::fill_n(peaks, bufsz, 0);
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}
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void
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PcmNormalizer::ProcessS16(int16_t *gcc_restrict dest,
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const std::span<const int16_t> src) noexcept
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{
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constexpr SampleFormat format = SampleFormat::S16;
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using Traits = SampleTraits<format>;
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using long_type = Traits::long_type;
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constexpr unsigned SHIFT = 10;
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int peakVal = 1;
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std::size_t peakPos = 0;
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for (std::size_t i = 0; i < src.size(); i++) {
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int val = src[i];
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if (val < 0)
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val = -val;
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if (val > peakVal)
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{
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peakVal = val;
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peakPos = i;
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}
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}
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pos = (pos + 1) % bufsz;
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peaks[pos] = peakVal;
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for (std::size_t i = 0; i < bufsz; i++) {
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if (peaks[i] > peakVal)
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{
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peakVal = peaks[i];
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peakPos = 0;
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}
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}
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//! Determine target gain
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long_type newGain = (1 << SHIFT)*target/peakVal;
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//! Adjust the gain with inertia from the previous gain value
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long_type curGain = prev_gain;
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newGain = (curGain*((1 << smooth) - 1) + newGain) >> smooth;
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//! Make sure it's no more than the maximum gain value
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if (newGain > (maxgain << SHIFT))
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newGain = maxgain << SHIFT;
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//! Make sure it's no less than 1:1
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if (newGain < (1 << SHIFT))
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newGain = 1 << SHIFT;
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//! Make sure the adjusted gain won't cause clipping
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std::size_t ramp = src.size();
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if ((peakVal*newGain >> SHIFT) > Traits::MAX)
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{
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newGain = (Traits::MAX << SHIFT)/peakVal;
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//! Truncate the ramp time
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ramp = peakPos;
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}
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//! Record the new gain
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prev_gain = newGain;
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if (!ramp)
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ramp = 1;
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if (!curGain)
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curGain = 1 << SHIFT;
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const long_type delta = (newGain - curGain) / (long_type)ramp;
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for (const auto sample : src.first(ramp)) {
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//! Amplify the sample
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*dest++ = PcmClamp<format>(sample * curGain >> SHIFT);
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//! Adjust the gain
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curGain += delta;
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}
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curGain = newGain;
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for (const auto sample : src.subspan(ramp)) {
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//! Amplify the sample
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*dest++ = PcmClamp<format>(sample * curGain >> SHIFT);
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}
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}
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