compress.c

   1 /*
   2  * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file compress.c Paraslash's dynamic audio range compressor. */
   8
   9 /*
  10  * Uses ideas of AudioCompress, (C) 2002-2004  M. Hari Nezumi <magenta@trikuare.cx>
  11  */
  12
  13 #include "para.h"
  14 #include "compress_filter.cmdline.h"
  15 #include "list.h"
  16 #include "sched.h"
  17 #include "filter.h"
  18 #include "string.h"
  19
  20 /** The size of the output data buffer. */
  21 #define COMPRESS_CHUNK_SIZE 40960
  22
  23 /** Data specific to the compress filter. */
  24 struct private_compress_data {
  25         /** The current multiplier. */
  26         unsigned current_gain;
  27         /** Points to the configuration data for this instance of the compress filter. */
  28         struct compress_filter_args_info *conf;
  29         /** Minimal admissible gain. */
  30         unsigned min_gain;
  31         /** Maximal admissible gain. */
  32         unsigned max_gain;
  33         /** Number of samples already seen. */
  34         unsigned num_samples;
  35         /** Absolute value of the maximal sample in the current block. */
  36         unsigned peak;
  37 };
  38
  39 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  40 {
  41         size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
  42                 (fn->bufsize - fn->loaded) / 2 * 2);
  43         struct private_compress_data *pcd = fn->private_data;
  44         int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
  45         unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
  46                 mask = (1 << pcd->conf->blocksize_arg) - 1;
  47
  48         if (!length)
  49                 return 0;
  50         for (i = 0; i < length / 2; i++) {
  51                 /* be careful in that heat, my dear */
  52                 int sample = *ip++, adjusted_sample;
  53
  54                 adjusted_sample = (PARA_ABS(sample) * pcd->current_gain)
  55                         >> gain_shift;
  56                 if (unlikely(adjusted_sample > 32767)) { /* clip */
  57                         PARA_NOTICE_LOG("clip: sample: %d, adjusted sample: %d\n",
  58                                 sample, adjusted_sample);
  59                         adjusted_sample = 32767;
  60                         pcd->current_gain = (3 * pcd->current_gain +
  61                                 (1 << pcd->conf->inertia_arg)) / 4;
  62                         pcd->peak = 0;
  63                 } else
  64                         pcd->peak = PARA_MAX(pcd->peak, adjusted_sample);
  65                 *op++ = sample >= 0? adjusted_sample : -adjusted_sample;
  66                 if (likely(++pcd->num_samples & mask))
  67                         continue;
  68                 if (pcd->peak < pcd->conf->target_level_arg) {
  69                         if (pcd->current_gain < pcd->max_gain)
  70                                 pcd->current_gain++;
  71                 } else {
  72                         if (pcd->current_gain > pcd->min_gain + 1)
  73                                 pcd->current_gain -= 2;
  74                 }
  75                 PARA_DEBUG_LOG("gain: %lu, peak: %d\n", pcd->current_gain,
  76                         pcd->peak);
  77                 pcd->peak = 0;
  78         }
  79         fn->loaded += length;
  80         return length;
  81 }
  82
  83 static void close_compress(struct filter_node *fn)
  84 {
  85         free(fn->private_data);
  86         free(fn->buf);
  87 }
  88
  89 static void *compress_parse_config(int argc, char **argv)
  90 {
  91         struct compress_filter_args_info *ret = para_calloc(sizeof(struct compress_filter_args_info));
  92         if (!compress_cmdline_parser(argc, argv, ret))
  93                 return ret;
  94         free(ret);
  95         return NULL;
  96 }
  97
  98 static void open_compress(struct filter_node *fn)
  99 {
 100         struct private_compress_data *pcd = para_calloc(
 101                 sizeof(struct private_compress_data));
 102         pcd->conf = fn->conf;
 103         fn->private_data = pcd;
 104         fn->bufsize = COMPRESS_CHUNK_SIZE;
 105         fn->buf = para_malloc(fn->bufsize);
 106         pcd->current_gain = 1 << pcd->conf->inertia_arg;
 107         pcd->min_gain = 1 << (pcd->conf->inertia_arg - pcd->conf->aggressiveness_arg);
 108         pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
 109 }
 110
 111 /**
 112  * The init function of the compress filter.
 113  *
 114  * \param f Pointer to the struct to initialize.
 115  */
 116 void compress_init(struct filter *f)
 117 {
 118         f->open = open_compress;
 119         f->close = close_compress;
 120         f->convert = compress;
 121         f->print_help = compress_cmdline_parser_print_help;
 122         f->parse_config = compress_parse_config;
 123 }