mpd/src/pcm/MixRampAnalyzer.hxx
2022-07-04 18:11:21 +02:00

89 lines
2.4 KiB
C++

/*
* Copyright 2003-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#pragma once
#include "ReplayGainAnalyzer.hxx"
#include "Chrono.hxx"
#include <span>
constexpr auto mixramp_volumes = std::array{
-90., -60., -40., -30., -24., -21., -18.,
-15., -12., -9., -6., -3., 0., 3., 6.,
};
struct MixRampItem {
FloatDuration time;
double volume;
constexpr bool operator==(const MixRampItem &other) const noexcept {
return time == other.time && volume == other.volume;
}
constexpr bool operator!=(const MixRampItem &other) const noexcept {
return !(*this == other);
}
};
using MixRampArray = std::array<MixRampItem, mixramp_volumes.size()>;
struct MixRampData {
MixRampArray start, end;
constexpr MixRampData() noexcept:start{}, end{} {
for (std::size_t i = 0; i < mixramp_volumes.size(); ++i) {
start[i].time = end[i].time = FloatDuration{-1};
start[i].volume = end[i].volume = mixramp_volumes[i];
}
}
void Add(MixRampItem item) noexcept;
};
/**
* Analyze a 44.1 kHz / stereo / float32 audio stream and calculate
* MixRamp tags.
*/
class MixRampAnalyzer {
static constexpr std::size_t chunk_duration_fraction = 10;
static constexpr std::size_t chunk_frames =
ReplayGainAnalyzer::SAMPLE_RATE / chunk_duration_fraction;
static constexpr FloatDuration chunk_duration{1.0 / chunk_duration_fraction};
WindowReplayGainAnalyzer gain_analyzer;
MixRampData result;
std::size_t chunk_number = 0;
std::size_t chunk_fill = 0;
public:
void Process(std::span<const ReplayGainAnalyzer::Frame> src) noexcept;
FloatDuration GetTime() const noexcept {
return chunk_number * chunk_duration;
}
const auto &GetResult() const noexcept {
return result;
}
};