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  * Used ideas of 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 /** the size of the output data buffer */
  32 #define COMPRESS_CHUNK_SIZE 40960
  33
  34 /** data specific to the compress filter */
  35 struct private_compress_data {
  36         /** the current multiplier */
  37         unsigned current_gain;
  38         /** points to the configuration data for this instance of the compress filter */
  39         struct compress_filter_args_info *conf;
  40         /** minimal admissible gain */
  41         unsigned min_gain;
  42         /** maximal admissible gain */
  43         unsigned max_gain;
  44         /** number of samples already seen */
  45         unsigned num_samples;
  46         /** absolute value of the maximal sample in the current block */
  47         unsigned peak;
  48 };
  49
  50 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  51 {
  52         size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
  53                 (fn->bufsize - fn->loaded) / 2 * 2);
  54         struct private_compress_data *pcd = fn->private_data;
  55         int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
  56         unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
  57                 mask = (1 << pcd->conf->blocksize_arg) - 1;
  58
  59         if (!length)
  60                 return 0;
  61         for (i = 0; i < length / 2; i++) {
  62                 /* be careful in that heat, my dear */
  63                 int sample = *ip++, adjusted_sample;
  64
  65                 if (sample > 0) {
  66                         adjusted_sample = (sample * pcd->current_gain)
  67                                 >> gain_shift;
  68                         if (unlikely(adjusted_sample > 32767)) {
  69                                 adjusted_sample = 32767;
  70                                 pcd->current_gain = (3 * pcd->current_gain +
  71                                         (1 << pcd->conf->inertia_arg)) / 4;
  72                                 pcd->peak = 0;
  73                         } else
  74                                 if (adjusted_sample > pcd->peak)
  75                                         pcd->peak = sample;
  76                 } else {
  77                         adjusted_sample = -((-sample * pcd->current_gain)
  78                                 >> gain_shift);
  79                         if (unlikely(adjusted_sample < -32768)) {
  80                                 adjusted_sample = -32768;
  81                                 pcd->current_gain = (3 * pcd->current_gain +
  82                                         (1 << pcd->conf->inertia_arg)) / 4;
  83                                 pcd->peak = 0;
  84                         } else
  85                                 if (-adjusted_sample > pcd->peak)
  86                                         pcd->peak = -adjusted_sample;
  87                 }
  88                 *op++ = adjusted_sample;
  89                 if (likely(++pcd->num_samples & mask))
  90                         continue;
  91                 if (pcd->peak < pcd->conf->target_level_arg) {
  92                         if (pcd->current_gain < pcd->max_gain)
  93                                 pcd->current_gain++;
  94                 } else {
  95                         if (pcd->current_gain > pcd->min_gain + 1)
  96                                 pcd->current_gain -= 2;
  97                 }
  98 //              PARA_DEBUG_LOG("gain: %lu, peak: %d\n", pcd->current_gain,
  99 //                      pcd->peak);
 100                 pcd->peak = 0;
 101 //              PARA_INFO_LOG("sample: %lu\n", ABS(sample));
 102         }
 103         fn->loaded += length;
 104         return length;
 105 }
 106
 107 static void close_compress(struct filter_node *fn)
 108 {
 109         free(fn->private_data);
 110         free(fn->buf);
 111 }
 112
 113 static void *compress_parse_config(int argc, char **argv)
 114 {
 115         struct compress_filter_args_info *ret = para_calloc(sizeof(struct compress_filter_args_info));
 116         if (!compress_cmdline_parser(argc, argv, ret))
 117                 return ret;
 118         free(ret);
 119         return NULL;
 120 }
 121
 122 static void open_compress(struct filter_node *fn)
 123 {
 124         struct private_compress_data *pcd = para_calloc(
 125                 sizeof(struct private_compress_data));
 126         pcd->conf = fn->conf;
 127         fn->private_data = pcd;
 128         fn->bufsize = COMPRESS_CHUNK_SIZE;
 129         fn->buf = para_malloc(fn->bufsize);
 130         pcd->current_gain = 1 << pcd->conf->inertia_arg;
 131         pcd->min_gain = 1 << (pcd->conf->inertia_arg - pcd->conf->aggressiveness_arg);
 132         pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
 133 }
 134
 135 /** the init function of the compress filter */
 136 void compress_init(struct filter *f)
 137 {
 138         f->open = open_compress;
 139         f->close = close_compress;
 140         f->convert = compress;
 141         f->print_help = compress_cmdline_parser_print_help;
 142         f->parse_config = compress_parse_config;
 143 }