MPD 0.17~git
src/pcm_mix.h
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00001 /*
00002  * Copyright (C) 2003-2011 The Music Player Daemon Project
00003  * http://www.musicpd.org
00004  *
00005  * This program is free software; you can redistribute it and/or modify
00006  * it under the terms of the GNU General Public License as published by
00007  * the Free Software Foundation; either version 2 of the License, or
00008  * (at your option) any later version.
00009  *
00010  * This program is distributed in the hope that it will be useful,
00011  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00013  * GNU General Public License for more details.
00014  *
00015  * You should have received a copy of the GNU General Public License along
00016  * with this program; if not, write to the Free Software Foundation, Inc.,
00017  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00018  */
00019 
00020 #ifndef PCM_MIX_H
00021 #define PCM_MIX_H
00022 
00023 #include "audio_format.h"
00024 
00025 #include <stdbool.h>
00026 #include <stddef.h>
00027 
00028 /*
00029  * Linearly mixes two PCM buffers.  Both must have the same length and
00030  * the same audio format.  The formula is:
00031  *
00032  *   s1 := s1 * portion1 + s2 * (1 - portion1)
00033  *
00034  * @param buffer1 the first PCM buffer, and the destination buffer
00035  * @param buffer2 the second PCM buffer
00036  * @param size the size of both buffers in bytes
00037  * @param format the sample format of both buffers
00038  * @param portion1 a number between 0.0 and 1.0 specifying the portion
00039  * of the first buffer in the mix; portion2 = (1.0 - portion1). The value
00040  * NaN is used by the MixRamp code to specify that simple addition is required.
00041  *
00042  * @return true on success, false if the format is not supported
00043  */
00044 G_GNUC_WARN_UNUSED_RESULT
00045 bool
00046 pcm_mix(void *buffer1, const void *buffer2, size_t size,
00047         enum sample_format format, float portion1);
00048 
00049 #endif