compress_filter.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_filter.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 "error.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 };
  39
  40 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  41 {
  42         size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
  43                 (fn->bufsize - fn->loaded) / 2 * 2);
  44         struct private_compress_data *pcd = fn->private_data;
  45         int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
  46         unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
  47                 mask = (1 << pcd->conf->blocksize_arg) - 1;
  48
  49         if (!length)
  50                 return 0;
  51         for (i = 0; i < length / 2; i++) {
  52                 /* be careful in that heat, my dear */
  53                 int sample = *ip++, adjusted_sample = (PARA_ABS(sample) *
  54                         pcd->current_gain) >> gain_shift;
  55                 if (unlikely(adjusted_sample > 32767)) { /* clip */
  56                         PARA_NOTICE_LOG("clip: sample: %d, adjusted sample: %d\n",
  57                                 sample, adjusted_sample);
  58                         adjusted_sample = 32767;
  59                         pcd->current_gain = (3 * pcd->current_gain +
  60                                 (1 << pcd->conf->inertia_arg)) / 4;
  61                         pcd->peak = 0;
  62                 } else
  63                         pcd->peak = PARA_MAX(pcd->peak, adjusted_sample);
  64                 *op++ = sample >= 0? adjusted_sample : -adjusted_sample;
  65                 if (likely(++pcd->num_samples & mask))
  66                         continue;
  67 //              PARA_DEBUG_LOG("gain: %u, peak: %u\n", pcd->current_gain,
  68 //                      pcd->peak);
  69                 if (pcd->peak < pcd->conf->target_level_arg) {
  70                         if (pcd->current_gain < pcd->max_gain)
  71                                 pcd->current_gain++;
  72                 } else
  73                         pcd->current_gain = PARA_MAX(pcd->current_gain - 2,
  74                                 1 << pcd->conf->inertia_arg);
  75                 pcd->peak = 0;
  76         }
  77         fn->loaded += length;
  78         return length;
  79 }
  80
  81 static void close_compress(struct filter_node *fn)
  82 {
  83         free(fn->private_data);
  84         free(fn->buf);
  85 }
  86
  87 /** TODO: Add sanity checks */
  88 static int compress_parse_config(int argc, char **argv, void **config)
  89 {
  90         int ret;
  91         struct compress_filter_args_info *compress_conf
  92                 = para_calloc(sizeof(*compress_conf));
  93
  94         ret = -E_COMPRESS_SYNTAX;
  95         if (compress_cmdline_parser(argc, argv, compress_conf))
  96                 goto err;
  97         *config = compress_conf;
  98         return 1;
  99 err:
 100         free(compress_conf);
 101         return  ret;
 102 }
 103
 104 static void open_compress(struct filter_node *fn)
 105 {
 106         struct private_compress_data *pcd = para_calloc(
 107                 sizeof(struct private_compress_data));
 108         pcd->conf = fn->conf;
 109         fn->private_data = pcd;
 110         fn->bufsize = COMPRESS_CHUNK_SIZE;
 111         fn->buf = para_malloc(fn->bufsize);
 112         pcd->current_gain = 1 << pcd->conf->inertia_arg;
 113         pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
 114 }
 115
 116 /**
 117  * The init function of the compress filter.
 118  *
 119  * \param f Pointer to the struct to initialize.
 120  */
 121 void compress_filter_init(struct filter *f)
 122 {
 123         f->open = open_compress;
 124         f->close = close_compress;
 125         f->convert = compress;
 126         f->print_help = compress_cmdline_parser_print_help;
 127         f->parse_config = compress_parse_config;
 128 }