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/*
* Copyright 2003-2020 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.
*/
#ifndef MPD_PCM_VOLUME_HXX
#define MPD_PCM_VOLUME_HXX
#include "SampleFormat.hxx"
#include "Buffer.hxx"
#include "Dither.hxx"
#ifndef NDEBUG
#include <cassert>
#endif
template<typename T> struct ConstBuffer;
/**
* Number of fractional bits for a fixed-point volume value.
*/
static constexpr unsigned PCM_VOLUME_BITS = 10;
/**
* This value means "100% volume".
*/
static constexpr unsigned PCM_VOLUME_1 = 1u << PCM_VOLUME_BITS;
static constexpr int PCM_VOLUME_1S = PCM_VOLUME_1;
/**
* Converts a float value (0.0 = silence, 1.0 = 100% volume) to an
* integer volume value (1000 = 100%).
*/
constexpr int
pcm_float_to_volume(float volume) noexcept
{
return int(volume * PCM_VOLUME_1 + 0.5f);
}
constexpr float
pcm_volume_to_float(int volume) noexcept
{
return (float)volume / (float)PCM_VOLUME_1;
}
/**
* Software volume implementation.
*/
class PcmVolume {
SampleFormat format;
/**
* Are we currently converting to a different #SampleFormat?
* This is set by Open().
*/
bool convert;
unsigned volume;
PcmBuffer buffer;
PcmDither dither;
public:
PcmVolume() noexcept
:volume(PCM_VOLUME_1) {
#ifndef NDEBUG
format = SampleFormat::UNDEFINED;
#endif
}
unsigned GetVolume() const noexcept {
return volume;
}
/**
* @param _volume the volume level in the range
* [0..#PCM_VOLUME_1]; may be bigger than #PCM_VOLUME_1, but
* then it will most likely clip a lot
*/
void SetVolume(unsigned _volume) noexcept {
volume = _volume;
}
/**
* Opens the object, prepare for Apply().
*
* Throws on error.
*
* @param format the input sample format
* @param allow_convert allow the class to convert to a
* different #SampleFormat to preserve quality?
* @return the output sample format
*/
SampleFormat Open(SampleFormat format, bool allow_convert);
/**
* Closes the object. After that, you may call Open() again.
*/
void Close() noexcept {
#ifndef NDEBUG
assert(format != SampleFormat::UNDEFINED);
format = SampleFormat::UNDEFINED;
#endif
}
/**
* Apply the volume level.
*/
gcc_pure
ConstBuffer<void> Apply(ConstBuffer<void> src) noexcept;
};
#endif
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