diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/normalize.c | 100 | ||||
| -rw-r--r-- | src/normalize.h | 21 |
2 files changed, 121 insertions, 0 deletions
diff --git a/src/normalize.c b/src/normalize.c new file mode 100644 index 000000000..8c48f13bd --- /dev/null +++ b/src/normalize.c @@ -0,0 +1,100 @@ +/* the Music Player Daemon (MPD) + * (c)2003-2006 by Warren Dukes (warren.dukes@gmail.com) + * This project's homepage is: 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <math.h> +#include <limits.h> + +#include "conf.h" +#include "normalize.h" +#include "playlist.h" + +/* silence level, apparently this is Wrong (tm) */ +#define SILENCE_LEVEL (SHRT_MAX * 0.01) +/* not sure what this is :) */ +#define MID (SHRT_MAX * 0.25) + +#define MUL_MIN 0.1 +#define MUL_MAX 5.0 +#define NSAMPLES 128 +#define MIN_SAMPLE_SIZE 32000 + +#define clamp(a,min,max) (((a)>(max))?(max):(((a)<(min))?(min):(a))) + +void normalizeData(char *buffer, int bufferSize, AudioFormat *format) +{ + static float multiplier = 1.0; + static int current_id = 0; + float average = 0.0; + static int old_song = 0; + int new_song = 0; + int total_length = 0; + int temp = 0; + int i = 0; + float root_mean_square = 0.0; /* the rms of the data */ + mpd_sint16 *data = (mpd_sint16 *) buffer; /* the audio data */ + int length = bufferSize / 2; /* the number of samples */ + static struct { + float avg; /* average sample 'level' */ + int len; /* sample size (used to weigh sample) */ + } mem[NSAMPLES]; + + /* operate only on 16 bit, 2 channel audio */ + if (format->bits != 16 && format->channels != 2) return; + + /* calculate the root mean square of the data */ + for (i = 0; i < length; i++) + root_mean_square += (float)(data[i] * data[i]); + + root_mean_square = sqrt(root_mean_square / (float)length); + + /* reset the multiplier if the song has changed */ + if (old_song != (new_song = getPlaylistCurrentSong())) { + old_song = new_song; + /* re-zero 'mem' */ + for (i = 0; i < NSAMPLES; i++) { + mem[i].avg = 0.0; + mem[i].len = 0; + } + current_id = 0; + } + + /* and now do magic tricks */ + for (i = 0; i < NSAMPLES; i++) { + average += mem[i].avg * (float)mem[i].len; + total_length += mem[i].len; + } + + if (total_length > MIN_SAMPLE_SIZE) { + average /= (float) total_length; + if (average >= SILENCE_LEVEL) { + multiplier = MID / average; + /* clamp multiplier */ + multiplier = clamp(multiplier, MUL_MIN, MUL_MAX); + } + } + + /* scale and clamp the samples */ + for (i = 0; i < length; i++) { + temp = data[i] * multiplier; + data[i] = clamp(temp, SHRT_MIN, SHRT_MAX); + } + + mem[current_id].len = bufferSize / 2; + mem[current_id].avg = multiplier * root_mean_square; + current_id = (current_id + 1) % NSAMPLES; /* increment current_id */ +} diff --git a/src/normalize.h b/src/normalize.h new file mode 100644 index 000000000..f131669a8 --- /dev/null +++ b/src/normalize.h @@ -0,0 +1,21 @@ +/* the Music Player Daemon (MPD) + * (c)2003-2006 by Warren Dukes (warren.dukes@gmail.com) + * This project's homepage is: 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include "audio.h" + +void normalizeData(char *buffer, int bufferSize, AudioFormat *format); |