131 lines
2.8 KiB
C++
131 lines
2.8 KiB
C++
/*
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* Copyright (C) 2003-2013 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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#ifndef MPD_PCM_VOLUME_HXX
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#define MPD_PCM_VOLUME_HXX
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#include "AudioFormat.hxx"
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#include "PcmBuffer.hxx"
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#include "PcmDither.hxx"
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#include <stdint.h>
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#include <stddef.h>
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#ifndef NDEBUG
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#include <assert.h>
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#endif
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class Error;
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template<typename T> struct ConstBuffer;
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/**
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* Number of fractional bits for a fixed-point volume value.
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*/
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static constexpr unsigned PCM_VOLUME_BITS = 10;
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/**
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* This value means "100% volume".
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*/
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static constexpr unsigned PCM_VOLUME_1 = 1024;
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static constexpr int PCM_VOLUME_1S = PCM_VOLUME_1;
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struct AudioFormat;
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/**
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* Converts a float value (0.0 = silence, 1.0 = 100% volume) to an
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* integer volume value (1000 = 100%).
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*/
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static inline int
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pcm_float_to_volume(float volume)
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{
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return volume * PCM_VOLUME_1 + 0.5;
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}
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static inline float
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pcm_volume_to_float(int volume)
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{
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return (float)volume / (float)PCM_VOLUME_1;
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}
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/**
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* A class that converts samples from one format to another.
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*/
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class PcmVolume {
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SampleFormat format;
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unsigned volume;
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PcmBuffer buffer;
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PcmDither dither;
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public:
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PcmVolume()
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:volume(PCM_VOLUME_1) {
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#ifndef NDEBUG
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format = SampleFormat::UNDEFINED;
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#endif
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}
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#ifndef NDEBUG
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~PcmVolume() {
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assert(format == SampleFormat::UNDEFINED);
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}
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#endif
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unsigned GetVolume() const {
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return volume;
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}
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/**
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* @param _volume the volume level in the range
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* [0..#PCM_VOLUME_1]; may be bigger than #PCM_VOLUME_1, but
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* then it will most likely clip a lot
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*/
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void SetVolume(unsigned _volume) {
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volume = _volume;
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}
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/**
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* Opens the object, prepare for Apply().
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*
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* @param format the sample format
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* @param error location to store the error
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* @return true on success
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*/
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bool Open(SampleFormat format, Error &error);
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/**
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* Closes the object. After that, you may call Open() again.
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*/
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void Close() {
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#ifndef NDEBUG
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assert(format != SampleFormat::UNDEFINED);
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format = SampleFormat::UNDEFINED;
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#endif
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}
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/**
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* Apply the volume level.
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*/
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gcc_pure
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ConstBuffer<void> Apply(ConstBuffer<void> src);
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};
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#endif
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