compress.c

   1 /*
   2  * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file compress.c paraslash's dynamic audio range compressor */
  20
  21 /*
  22  * Based on AudioCompress, (C) 2002-2004  M. Hari Nezumi <magenta@trikuare.cx>
  23  */
  24
  25 #include "gcc-compat.h"
  26 #include "para.h"
  27 #include "compress_filter.cmdline.h"
  28 #include "list.h"
  29 #include "filter.h"
  30 #include "string.h"
  31
  32 /** how fine-grained the gain is */
  33 #define GAINSHIFT 10
  34 /** the size of the output data buffer */
  35 #define COMPRESS_CHUNK_SIZE 40960
  36
  37 /** data specific to the compress filter */
  38 struct private_compress_data {
  39         /** an array holding the previous peak values */
  40         int *peaks;
  41         /** current bucket number to be modified */
  42         unsigned pn;
  43         /** number of times clipping occured */
  44         unsigned clip;
  45         /** the current multiplier */
  46         int current_gain;
  47         /** the target multiplier */
  48         int target_gain;
  49         /** pointer to the configuration data for this instance of the compress filter */
  50         struct gengetopt_args_info *conf;
  51 };
  52
  53 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  54 {
  55         int16_t *audio = (int16_t *) inbuf, *ip = audio, *op;
  56         int peak = 1, pos = 0, i, gr, gf, gn;
  57         size_t length = MIN((inbuf_len / 2) * 2, (fn->bufsize - fn->loaded) / 2 * 2);
  58         struct private_compress_data *pcd = fn->private_data;
  59
  60         if (!length)
  61                 return 0;
  62         /* determine peak's value and position */
  63         for (i = 0; i < length / 2; i++, ip++) {
  64                 int val = ABS(*ip);
  65                 if (val > peak) {
  66                         peak = val;
  67                         pos = i;
  68                 }
  69         }
  70         pcd->peaks[pcd->pn] = peak;
  71         for (i = 0; i < pcd->conf->buckets_arg; i++) {
  72                 if (pcd->peaks[i] > peak) {
  73                         peak = pcd->peaks[i];
  74                         pos = 0;
  75                 }
  76         }
  77         /* determine target gain */
  78         gn = (1 << GAINSHIFT) * pcd->conf->target_level_arg / peak;
  79         if (gn < (1 << GAINSHIFT))
  80                 gn = 1 << GAINSHIFT;
  81         pcd->target_gain = (pcd->target_gain * ((1 << pcd->conf->gain_smooth_arg) - 1) + gn)
  82                 >> pcd->conf->gain_smooth_arg;
  83         /* give it an extra insignificant nudge to counteract possible
  84          * rounding error
  85          */
  86         if (gn < pcd->target_gain)
  87                 pcd->target_gain--;
  88         else if (gn > pcd->target_gain)
  89                 pcd->target_gain++;
  90         if (pcd->target_gain > pcd->conf->gain_max_arg << GAINSHIFT)
  91                 pcd->target_gain = pcd->conf->gain_max_arg << GAINSHIFT;
  92         /* see if a peak is going to clip */
  93         gn = (1 << GAINSHIFT) * 32768 / peak;
  94         if (gn < pcd->target_gain) {
  95                 pcd->target_gain = gn;
  96                 if (pcd->conf->anticlip_given)
  97                         pos = 0;
  98         } else
  99                 /* we're ramping up, so draw it out over the whole frame */
 100                 pos = length;
 101         /* determine gain rate necessary to make target */
 102         if (!pos)
 103                 pos = 1;
 104         gr = ((pcd->target_gain - pcd->current_gain) << 16) / pos;
 105         gf = pcd->current_gain << 16;
 106         ip = audio;
 107         op = (int16_t *)(fn->buf + fn->loaded);
 108         for (i = 0; i < length / 2; i++) {
 109                 int sample;
 110                 /* interpolate the gain */
 111                 pcd->current_gain = gf >> 16;
 112                 if (i < pos)
 113                         gf += gr;
 114                 else if (i == pos)
 115                         gf = pcd->target_gain << 16;
 116                 /* amplify */
 117                 sample = (*ip++) * pcd->current_gain * pcd->conf->volume_arg / 10 >> GAINSHIFT;
 118                 if (sample < -32768) {
 119                         pcd->clip++;
 120                         sample = -32768;
 121                 } else if (sample > 32767) {
 122                         pcd->clip++;
 123                         sample = 32767;
 124                 }
 125                 *op++ = sample;
 126         }
 127         pcd->pn = (pcd->pn + 1) % pcd->conf->buckets_arg;
 128         PARA_DEBUG_LOG("bucket: %03i, input len: %i, length: %i, peak: %05i, "
 129                 "current gain: %03i, clipped: %d\n", pcd->pn, inbuf_len,
 130                 length, peak, pcd->current_gain, pcd->clip);
 131         fn->loaded = length;
 132         return length;
 133 }
 134
 135 static void close_compress(struct filter_node *fn)
 136 {
 137         struct private_compress_data *pcd = fn->private_data;
 138         free(pcd->peaks);
 139         free(fn->private_data);
 140         free(fn->buf);
 141 }
 142
 143 static void *compress_parse_config(int argc, char **argv)
 144 {
 145         struct gengetopt_args_info *ret = para_calloc(sizeof(struct gengetopt_args_info));
 146         if (!compress_cmdline_parser(argc, argv, ret))
 147                 return ret;
 148         free(ret);
 149         return NULL;
 150 }
 151
 152 static void open_compress(struct filter_node *fn)
 153 {
 154         struct private_compress_data *pcd = para_calloc(
 155                 sizeof(struct private_compress_data));
 156 //      compress_cmdline_parser(fn->argc, fn->argv, &pcd->conf);
 157         pcd->conf = fn->conf;
 158         pcd->peaks = para_calloc(pcd->conf->buckets_arg * sizeof(int));
 159         fn->private_data = pcd;
 160         fn->bufsize = COMPRESS_CHUNK_SIZE;
 161         fn->buf = para_malloc(fn->bufsize);
 162         fn->loaded = 0;
 163 }
 164
 165 /** the init function of the compress filter */
 166 void compress_init(struct filter *f)
 167 {
 168         f->open = open_compress;
 169         f->close = close_compress;
 170         f->convert = compress;
 171         f->print_help = compress_cmdline_parser_print_help;
 172         f->parse_config = compress_parse_config;
 173 }