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 "para.h"
  26 #include "compress_filter.cmdline.h"
  27 #include "list.h"
  28 #include "filter.h"
  29 #include "string.h"
  30
  31 /** how fine-grained the gain is */
  32 #define GAINSHIFT 10
  33 /** the size of the output data buffer */
  34 #define COMPRESS_CHUNK_SIZE 40960
  35
  36 /** data specific to the compress filter */
  37 struct private_compress_data {
  38         /** an array holding the previous peak values */
  39         int *peaks;
  40         /** current bucket number to be modified */
  41         unsigned pn;
  42         /** number of times clipping occured */
  43         unsigned clip;
  44         /** the current multiplier */
  45         int current_gain;
  46         /** the target multiplier */
  47         int target_gain;
  48         /** pointer to the configuration data for this instance of the compress filter */
  49         struct gengetopt_args_info *conf;
  50 };
  51
  52 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  53 {
  54         int16_t *audio = (int16_t *) inbuf, *ip = audio, *op;
  55         int peak = 1, pos = 0, i, gr, gf, gn;
  56         size_t length = MIN((inbuf_len / 2) * 2, (fn->bufsize - fn->loaded) / 2 * 2);
  57         struct private_compress_data *pcd = fn->private_data;
  58
  59         if (!length)
  60                 return 0;
  61         /* determine peak's value and position */
  62         for (i = 0; i < length / 2; i++, ip++) {
  63                 int val = ABS(*ip);
  64                 if (val > peak) {
  65                         peak = val;
  66                         pos = i;
  67                 }
  68         }
  69         pcd->peaks[pcd->pn] = peak;
  70         for (i = 0; i < pcd->conf->buckets_arg; i++) {
  71                 if (pcd->peaks[i] > peak) {
  72                         peak = pcd->peaks[i];
  73                         pos = 0;
  74                 }
  75         }
  76         /* determine target gain */
  77         gn = (1 << GAINSHIFT) * pcd->conf->target_level_arg / peak;
  78         if (gn < (1 << GAINSHIFT))
  79                 gn = 1 << GAINSHIFT;
  80         pcd->target_gain = (pcd->target_gain * ((1 << pcd->conf->gain_smooth_arg) - 1) + gn)
  81                 >> pcd->conf->gain_smooth_arg;
  82         /* give it an extra insignificant nudge to counteract possible
  83          * rounding error
  84          */
  85         if (gn < pcd->target_gain)
  86                 pcd->target_gain--;
  87         else if (gn > pcd->target_gain)
  88                 pcd->target_gain++;
  89         if (pcd->target_gain > pcd->conf->gain_max_arg << GAINSHIFT)
  90                 pcd->target_gain = pcd->conf->gain_max_arg << GAINSHIFT;
  91         /* see if a peak is going to clip */
  92         gn = (1 << GAINSHIFT) * 32768 / peak;
  93         if (gn < pcd->target_gain) {
  94                 pcd->target_gain = gn;
  95                 if (pcd->conf->anticlip_given)
  96                         pos = 0;
  97         } else
  98                 /* we're ramping up, so draw it out over the whole frame */
  99                 pos = length;
 100         /* determine gain rate necessary to make target */
 101         if (!pos)
 102                 pos = 1;
 103         gr = ((pcd->target_gain - pcd->current_gain) << 16) / pos;
 104         gf = pcd->current_gain << 16;
 105         ip = audio;
 106         op = (int16_t *)(fn->buf + fn->loaded);
 107         for (i = 0; i < length / 2; i++) {
 108                 int sample;
 109                 /* interpolate the gain */
 110                 pcd->current_gain = gf >> 16;
 111                 if (i < pos)
 112                         gf += gr;
 113                 else if (i == pos)
 114                         gf = pcd->target_gain << 16;
 115                 /* amplify */
 116                 sample = (*ip++) * pcd->current_gain * pcd->conf->volume_arg / 10 >> GAINSHIFT;
 117                 if (sample < -32768) {
 118                         pcd->clip++;
 119                         sample = -32768;
 120                 } else if (sample > 32767) {
 121                         pcd->clip++;
 122                         sample = 32767;
 123                 }
 124                 *op++ = sample;
 125         }
 126         pcd->pn = (pcd->pn + 1) % pcd->conf->buckets_arg;
 127         PARA_DEBUG_LOG("bucket: %03i, input len: %i, length: %i, peak: %05i, "
 128                 "current gain: %03i, clipped: %d\n", pcd->pn, inbuf_len,
 129                 length, peak, pcd->current_gain, pcd->clip);
 130         fn->loaded = length;
 131         return length;
 132 }
 133
 134 static void close_compress(struct filter_node *fn)
 135 {
 136         struct private_compress_data *pcd = fn->private_data;
 137         free(pcd->peaks);
 138         free(fn->private_data);
 139         free(fn->buf);
 140 }
 141
 142 static void *compress_parse_config(int argc, char **argv)
 143 {
 144         struct gengetopt_args_info *ret = para_calloc(sizeof(struct gengetopt_args_info));
 145         if (!compress_cmdline_parser(argc, argv, ret))
 146                 return ret;
 147         free(ret);
 148         return NULL;
 149 }
 150
 151 static void open_compress(struct filter_node *fn)
 152 {
 153         struct private_compress_data *pcd = para_calloc(
 154                 sizeof(struct private_compress_data));
 155 //      compress_cmdline_parser(fn->argc, fn->argv, &pcd->conf);
 156         pcd->conf = fn->conf;
 157         pcd->peaks = para_calloc(pcd->conf->buckets_arg * sizeof(int));
 158         fn->private_data = pcd;
 159         fn->bufsize = COMPRESS_CHUNK_SIZE;
 160         fn->buf = para_malloc(fn->bufsize);
 161         fn->loaded = 0;
 162 }
 163
 164 /** the init function of the compress filter */
 165 void compress_init(struct filter *f)
 166 {
 167         f->open = open_compress;
 168         f->close = close_compress;
 169         f->convert = compress;
 170         f->print_help = compress_cmdline_parser_print_help;
 171         f->parse_config = compress_parse_config;
 172 }