af99f9fc90
Applying software volume to S16 samples means several bits of precision are lost; at 25% volume, two bits are lost. Additionally, dithering adds some noise. The problem gets worse when you apply the software volume code twice: for the software mixer volume, and again for the replay gain. This loses some more precision and adds even more dithering noise, which can become audible (see https://github.com/MusicPlayerDaemon/MPD/issues/542). By converting everything to 24 bit, we need to shift only two bits to the right instead of ten, losing nearly no precision, and dithering is not needed. Even if the output device is unable to play S24 directly, we can convert back to S16 with only one stage of dithering. Closes https://github.com/MusicPlayerDaemon/MPD/issues/542
161 lines
4.0 KiB
C++
161 lines
4.0 KiB
C++
/*
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* Copyright 2003-2019 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "pcm/Volume.hxx"
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#include "pcm/Traits.hxx"
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#include "util/ConstBuffer.hxx"
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#include "test_pcm_util.hxx"
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#include <gtest/gtest.h>
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#include <algorithm>
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#include <string.h>
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template<SampleFormat F, class Traits=SampleTraits<F>,
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typename G=RandomInt<typename Traits::value_type>>
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static void
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TestVolume(G g=G())
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{
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typedef typename Traits::value_type value_type;
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PcmVolume pv;
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EXPECT_EQ(pv.Open(F, false), F);
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constexpr size_t N = 509;
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static value_type zero[N];
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const auto _src = TestDataBuffer<value_type, N>(g);
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const ConstBuffer<void> src(_src, sizeof(_src));
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pv.SetVolume(0);
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auto dest = pv.Apply(src);
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EXPECT_EQ(src.size, dest.size);
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EXPECT_EQ(0, memcmp(dest.data, zero, sizeof(zero)));
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pv.SetVolume(PCM_VOLUME_1);
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dest = pv.Apply(src);
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EXPECT_EQ(src.size, dest.size);
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EXPECT_EQ(0, memcmp(dest.data, src.data, src.size));
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pv.SetVolume(PCM_VOLUME_1 / 2);
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dest = pv.Apply(src);
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EXPECT_EQ(src.size, dest.size);
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const auto _dest = ConstBuffer<value_type>::FromVoid(dest);
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for (unsigned i = 0; i < N; ++i) {
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const auto expected = (_src[i] + 1) / 2;
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EXPECT_GE(_dest[i], expected - 4);
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EXPECT_LE(_dest[i], expected + 4);
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}
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pv.Close();
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}
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TEST(PcmTest, Volume8)
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{
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TestVolume<SampleFormat::S8>();
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}
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TEST(PcmTest, Volume16)
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{
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TestVolume<SampleFormat::S16>();
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}
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TEST(PcmTest, Volume16to32)
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{
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constexpr SampleFormat F = SampleFormat::S16;
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typedef int16_t value_type;
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RandomInt<value_type> g;
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PcmVolume pv;
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EXPECT_EQ(pv.Open(F, true), SampleFormat::S24_P32);
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constexpr size_t N = 509;
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static value_type zero[N];
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const auto _src = TestDataBuffer<value_type, N>(g);
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const ConstBuffer<void> src(_src, sizeof(_src));
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pv.SetVolume(0);
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auto dest = pv.Apply(src);
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EXPECT_EQ(src.size * 2, dest.size);
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EXPECT_EQ(0, memcmp(dest.data, zero, sizeof(zero)));
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pv.SetVolume(PCM_VOLUME_1);
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dest = pv.Apply(src);
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EXPECT_EQ(src.size * 2, dest.size);
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auto s = ConstBuffer<int16_t>::FromVoid(src);
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auto d = ConstBuffer<int32_t>::FromVoid(dest);
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for (size_t i = 0; i < N; ++i)
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EXPECT_EQ(d[i], s[i] << 8);
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pv.SetVolume(PCM_VOLUME_1 / 2);
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dest = pv.Apply(src);
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EXPECT_EQ(src.size * 2, dest.size);
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s = ConstBuffer<int16_t>::FromVoid(src);
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d = ConstBuffer<int32_t>::FromVoid(dest);
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for (unsigned i = 0; i < N; ++i) {
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const int32_t expected = (s[i] << 8) / 2;
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EXPECT_EQ(d[i], expected);
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}
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pv.Close();
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}
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TEST(PcmTest, Volume24)
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{
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TestVolume<SampleFormat::S24_P32>(RandomInt24());
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}
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TEST(PcmTest, Volume32)
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{
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TestVolume<SampleFormat::S32>();
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}
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TEST(PcmTest, VolumeFloat)
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{
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PcmVolume pv;
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pv.Open(SampleFormat::FLOAT, false);
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constexpr size_t N = 509;
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static float zero[N];
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const auto _src = TestDataBuffer<float, N>(RandomFloat());
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const ConstBuffer<void> src(_src, sizeof(_src));
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pv.SetVolume(0);
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auto dest = pv.Apply(src);
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EXPECT_EQ(src.size, dest.size);
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EXPECT_EQ(0, memcmp(dest.data, zero, sizeof(zero)));
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pv.SetVolume(PCM_VOLUME_1);
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dest = pv.Apply(src);
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EXPECT_EQ(src.size, dest.size);
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EXPECT_EQ(0, memcmp(dest.data, src.data, src.size));
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pv.SetVolume(PCM_VOLUME_1 / 2);
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dest = pv.Apply(src);
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EXPECT_EQ(src.size, dest.size);
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const auto _dest = ConstBuffer<float>::FromVoid(dest);
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for (unsigned i = 0; i < N; ++i)
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EXPECT_NEAR(_src[i] / 2, _dest[i], 1);
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pv.Close();
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}
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