0aee49bdf8
This updates the copyright header to all be the same, which is pretty much an update of where to mail request for a copy of the GPL and the years of the MPD project. This also puts all committers under 'The Music Player Project' umbrella. These entries should go individually in the AUTHORS file, for consistancy.
75 lines
1.9 KiB
C
75 lines
1.9 KiB
C
/*
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* Copyright (C) 2003-2009 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 PCM_VOLUME_H
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#define PCM_VOLUME_H
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#include "pcm_prng.h"
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#include <stdint.h>
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#include <stdbool.h>
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enum {
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/** this value means "100% volume" */
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PCM_VOLUME_1 = 1024,
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};
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struct audio_format;
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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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/**
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* Returns the next volume dithering number, between -511 and +511.
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* This number is taken from a global PRNG, see pcm_prng().
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*/
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static inline int
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pcm_volume_dither(void)
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{
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static unsigned long state;
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uint32_t r;
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r = state = pcm_prng(state);
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return (r & 511) - ((r >> 9) & 511);
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}
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/**
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* Adjust the volume of the specified PCM buffer.
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*
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* @param buffer the PCM buffer
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* @param length the length of the PCM buffer
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* @param format the audio format of the PCM buffer
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* @param volume the volume between 0 and #PCM_VOLUME_1
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* @return true on success, false if the audio format is not supported
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*/
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bool
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pcm_volume(void *buffer, int length,
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const struct audio_format *format,
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int volume);
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#endif
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