src/crossfade.h

   1 /*
   2  * Copyright (C) 2003-2009 The Music Player Daemon Project
   3  * http://www.musicpd.org
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #ifndef MPD_CROSSFADE_H
  21 #define MPD_CROSSFADE_H
  22
  23 struct audio_format;
  24 struct music_chunk;
  25
  26 /**
  27  * Calculate how many music pipe chunks should be used for crossfading.
  28  *
  29  * @param duration the requested crossfade duration
  30  * @param total_time total_time the duration of the new song
  31  * @param af the audio format of the new song
  32  * @param old_format the audio format of the current song
  33  * @param max_chunks the maximum number of chunks
  34  * @return the number of chunks for crossfading, or 0 if cross fading
  35  * should be disabled for this song change
  36  */
  37 unsigned cross_fade_calc(float duration, float total_time,
  38                          const struct audio_format *af,
  39                          const struct audio_format *old_format,
  40                          unsigned max_chunks);
  41
  42 /**
  43  * Applies cross fading to two chunks, i.e. mixes these chunks.
  44  * Internally, this calls pcm_mix().
  45  *
  46  * @param a the chunk in the current song (and the destination chunk)
  47  * @param b the according chunk in the new song
  48  * @param format the audio format of both chunks (must be the same)
  49  * @param current_chunk the relative index of the current chunk
  50  * @param num_chunks the number of chunks used for cross fading
  51  */
  52 void cross_fade_apply(struct music_chunk *a, const struct music_chunk *b,
  53                       const struct audio_format *format,
  54                       unsigned int current_chunk, unsigned int num_chunks);
  55
  56 #endif