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 #include "audiod.h"
  20
  21 /** The size of the output data buffer. */
  22 #define COMPRESS_CHUNK_SIZE 40960
  23
  24 extern char *stat_item_values[NUM_STAT_ITEMS];
  25
  26 /** Data specific to the compress filter. */
  27 struct private_compress_data {
  28         /** The current multiplier. */
  29         unsigned current_gain;
  30         /** Points to the configuration data for this instance of the compress filter. */
  31         struct compress_filter_args_info *conf;
  32         /** Maximal admissible gain. */
  33         unsigned max_gain;
  34         /** Number of samples already seen. */
  35         unsigned num_samples;
  36         /** Absolute value of the maximal sample in the current block. */
  37         unsigned peak;
  38         /** Amplification factor. */
  39         unsigned amp;
  40 };
  41
  42 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  43 {
  44         size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
  45                 (fn->bufsize - fn->loaded) / 2 * 2);
  46         struct private_compress_data *pcd = fn->private_data;
  47         int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
  48         unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
  49                 mask = (1 << pcd->conf->blocksize_arg) - 1;
  50
  51         if (!length)
  52                 return 0;
  53         for (i = 0; i < length / 2; i++) {
  54                 /* be careful in that heat, my dear */
  55                 int sample = *ip++, adjusted_sample = (PARA_ABS(sample) * (64 + pcd->amp)) >> 6;
  56
  57                 adjusted_sample = (adjusted_sample * pcd->current_gain) >> gain_shift;
  58                 if (unlikely(adjusted_sample > 32767)) { /* clip */
  59                         PARA_NOTICE_LOG("clip: sample: %d, adjusted sample: %d\n",
  60                                 sample, adjusted_sample);
  61                         adjusted_sample = 32767;
  62                         pcd->current_gain = (3 * pcd->current_gain +
  63                                 (1 << pcd->conf->inertia_arg)) / 4;
  64                         pcd->peak = 0;
  65                 } else
  66                         pcd->peak = PARA_MAX(pcd->peak, adjusted_sample);
  67                 *op++ = sample >= 0? adjusted_sample : -adjusted_sample;
  68                 if (likely(++pcd->num_samples & mask))
  69                         continue;
  70 //              PARA_DEBUG_LOG("gain: %u, peak: %u\n", pcd->current_gain,
  71 //                      pcd->peak);
  72                 if (pcd->peak < pcd->conf->target_level_arg) {
  73                         if (pcd->current_gain < pcd->max_gain)
  74                                 pcd->current_gain++;
  75                 } else
  76                         pcd->current_gain = PARA_MAX(pcd->current_gain - 2,
  77                                 1 << pcd->conf->inertia_arg);
  78                 pcd->peak = 0;
  79         }
  80         fn->loaded += length;
  81         return length;
  82 }
  83
  84 static void close_compress(struct filter_node *fn)
  85 {
  86         free(fn->private_data);
  87         free(fn->buf);
  88 }
  89
  90 static void *compress_parse_config(int argc, char **argv)
  91 {
  92         struct compress_filter_args_info *ret = para_calloc(sizeof(struct compress_filter_args_info));
  93         if (!compress_cmdline_parser(argc, argv, ret))
  94                 return ret;
  95         free(ret);
  96         return NULL;
  97 }
  98
  99 static void open_compress(struct filter_node *fn)
 100 {
 101         struct private_compress_data *pcd = para_calloc(
 102                 sizeof(struct private_compress_data));
 103         pcd->conf = fn->conf;
 104         fn->private_data = pcd;
 105         fn->bufsize = COMPRESS_CHUNK_SIZE;
 106         fn->buf = para_malloc(fn->bufsize);
 107         pcd->current_gain = 1 << pcd->conf->inertia_arg;
 108         pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
 109         if (stat_item_values[SI_AMPLIFICATION])
 110                 sscanf(stat_item_values[SI_AMPLIFICATION], "%u", &pcd->amp);
 111         PARA_NOTICE_LOG("amplification: %u (scaling factor: %1.2f)\n", pcd->amp,
 112                 pcd->amp / 64.0 + 1.0);
 113 }
 114
 115 /**
 116  * The init function of the compress filter.
 117  *
 118  * \param f Pointer to the struct to initialize.
 119  */
 120 void compress_init(struct filter *f)
 121 {
 122         f->open = open_compress;
 123         f->close = close_compress;
 124         f->convert = compress;
 125         f->print_help = compress_cmdline_parser_print_help;
 126         f->parse_config = compress_parse_config;
 127 }