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         /** Maximal admissible gain. */
  30         unsigned max_gain;
  31         /** Number of samples already seen. */
  32         unsigned num_samples;
  33         /** Absolute value of the maximal sample in the current block. */
  34         unsigned peak;
  35 };
  36
  37 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  38 {
  39         size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
  40                 (fn->bufsize - fn->loaded) / 2 * 2);
  41         struct private_compress_data *pcd = fn->private_data;
  42         int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
  43         unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
  44                 mask = (1 << pcd->conf->blocksize_arg) - 1;
  45
  46         if (!length)
  47                 return 0;
  48         for (i = 0; i < length / 2; i++) {
  49                 /* be careful in that heat, my dear */
  50                 int sample = *ip++, adjusted_sample;
  51
  52                 adjusted_sample = (PARA_ABS(sample) * pcd->current_gain)
  53                         >> gain_shift;
  54                 if (unlikely(adjusted_sample > 32767)) { /* clip */
  55                         PARA_NOTICE_LOG("clip: sample: %d, adjusted sample: %d\n",
  56                                 sample, adjusted_sample);
  57                         adjusted_sample = 32767;
  58                         pcd->current_gain = (3 * pcd->current_gain +
  59                                 (1 << pcd->conf->inertia_arg)) / 4;
  60                         pcd->peak = 0;
  61                 } else
  62                         pcd->peak = PARA_MAX(pcd->peak, adjusted_sample);
  63                 *op++ = sample >= 0? adjusted_sample : -adjusted_sample;
  64                 if (likely(++pcd->num_samples & mask))
  65                         continue;
  66 //              PARA_DEBUG_LOG("gain: %u, peak: %u\n", pcd->current_gain,
  67 //                      pcd->peak);
  68                 if (pcd->peak < pcd->conf->target_level_arg) {
  69                         if (pcd->current_gain < pcd->max_gain)
  70                                 pcd->current_gain++;
  71                 } else
  72                         pcd->current_gain = PARA_MAX(pcd->current_gain - 2,
  73                                 1 << pcd->conf->inertia_arg);
  74                 pcd->peak = 0;
  75         }
  76         fn->loaded += length;
  77         return length;
  78 }
  79
  80 static void close_compress(struct filter_node *fn)
  81 {
  82         free(fn->private_data);
  83         free(fn->buf);
  84 }
  85
  86 static void *compress_parse_config(int argc, char **argv)
  87 {
  88         struct compress_filter_args_info *ret = para_calloc(sizeof(struct compress_filter_args_info));
  89         if (!compress_cmdline_parser(argc, argv, ret))
  90                 return ret;
  91         free(ret);
  92         return NULL;
  93 }
  94
  95 static void open_compress(struct filter_node *fn)
  96 {
  97         struct private_compress_data *pcd = para_calloc(
  98                 sizeof(struct private_compress_data));
  99         pcd->conf = fn->conf;
 100         fn->private_data = pcd;
 101         fn->bufsize = COMPRESS_CHUNK_SIZE;
 102         fn->buf = para_malloc(fn->bufsize);
 103         pcd->current_gain = 1 << pcd->conf->inertia_arg;
 104         pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
 105 }
 106
 107 /**
 108  * The init function of the compress filter.
 109  *
 110  * \param f Pointer to the struct to initialize.
 111  */
 112 void compress_init(struct filter *f)
 113 {
 114         f->open = open_compress;
 115         f->close = close_compress;
 116         f->convert = compress;
 117         f->print_help = compress_cmdline_parser_print_help;
 118         f->parse_config = compress_parse_config;
 119 }