compress_filter.c

   1 /* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file compress_filter.c Paraslash's dynamic audio range compressor. */
   4
   5 /*
   6  * Uses ideas of AudioCompress, (C) 2002-2004  M. Hari Nezumi <magenta@trikuare.cx>
   7  */
   8
   9 #include <regex.h>
  10 #include <lopsub.h>
  11
  12 #include "filter_cmd.lsg.h"
  13 #include "para.h"
  14 #include "list.h"
  15 #include "sched.h"
  16 #include "buffer_tree.h"
  17 #include "filter.h"
  18 #include "string.h"
  19 #include "error.h"
  20
  21 #define U32_OPTVAL(_opt, _lpr) (FILTER_CMD_OPT_UINT32_VAL(COMPRESS, _opt, _lpr))
  22
  23 /** Data specific to the compress filter. */
  24 struct private_compress_data {
  25         /** The current multiplier. */
  26         unsigned current_gain;
  27         /** Maximal admissible gain. */
  28         unsigned max_gain;
  29         /** Number of samples already seen. */
  30         unsigned num_samples;
  31         /** Absolute value of the maximal sample in the current block. */
  32         int peak;
  33 };
  34
  35 static void compress_close(struct filter_node *fn)
  36 {
  37         free(fn->private_data);
  38 }
  39
  40 static int compress_post_select(__a_unused struct sched *s, void *context)
  41 {
  42         struct filter_node *fn = context;
  43         struct private_compress_data *pcd = fn->private_data;
  44         struct btr_node *btrn = fn->btrn;
  45         bool inplace = btr_inplace_ok(btrn);
  46         int ret;
  47         char *inbuf;
  48         size_t length, i;
  49         int16_t *ip, *op;
  50         uint32_t inertia = U32_OPTVAL(INERTIA, fn->lpr);
  51         unsigned gain_shift = inertia + U32_OPTVAL(DAMP, fn->lpr),
  52                 mask = (1 << U32_OPTVAL(BLOCKSIZE, fn->lpr)) - 1;
  53         //inplace = false;
  54 next_buffer:
  55         ret = btr_node_status(btrn, fn->min_iqs, BTR_NT_INTERNAL);
  56         if (ret < 0)
  57                 goto err;
  58         if (ret == 0)
  59                 return 0;
  60         btr_merge(btrn, fn->min_iqs);
  61         length = btr_next_buffer(btrn, &inbuf) & ~(size_t)1;
  62         if (length == 0) { /* eof and 1 byte available */
  63                 ret = -E_COMPRESS_EOF;
  64                 goto err;
  65         }
  66         ip = (int16_t *)inbuf;
  67         if (inplace)
  68                 op = ip;
  69         else
  70                 op = para_malloc(length);
  71         for (i = 0; i < length / 2; i++) {
  72                 /* be careful in that heat, my dear */
  73                 int sample = *ip++;
  74                 bool neg = false;
  75
  76                 if (sample < 0) {
  77                         sample = -sample;
  78                         neg = true;
  79                 }
  80                 sample *= pcd->current_gain;
  81                 sample >>= gain_shift;
  82                 if (sample > 32767) { /* clip */
  83                         sample = 32767;
  84                         pcd->current_gain = (3 * pcd->current_gain +
  85                                 (1 << inertia)) / 4;
  86                         pcd->peak = 0;
  87                 } else if (sample > pcd->peak)
  88                         pcd->peak = sample;
  89                 op[i] = neg? -sample : sample;
  90                 if (++pcd->num_samples & mask)
  91                         continue;
  92 //              PARA_DEBUG_LOG("gain: %u, peak: %u\n", pcd->current_gain,
  93 //                      pcd->peak);
  94                 if (pcd->peak < U32_OPTVAL(TARGET_LEVEL, fn->lpr)) {
  95                         if (pcd->current_gain < pcd->max_gain)
  96                                 pcd->current_gain++;
  97                 } else
  98                         pcd->current_gain = PARA_MAX(pcd->current_gain - 2,
  99                                 1U << inertia);
 100                 pcd->peak = 0;
 101         }
 102         if (inplace)
 103                 btr_pushdown_one(btrn);
 104         else {
 105                 btr_consume(btrn, length);
 106                 btr_add_output((char *)op, length, btrn);
 107         }
 108         goto next_buffer;
 109 err:
 110         assert(ret < 0);
 111         btr_remove_node(&fn->btrn);
 112         return ret;
 113 }
 114
 115 static void compress_open(struct filter_node *fn)
 116 {
 117         struct private_compress_data *pcd = para_calloc(sizeof(*pcd));
 118         uint32_t inertia = U32_OPTVAL(INERTIA, fn->lpr);
 119         uint32_t aggressiveness = U32_OPTVAL(AGGRESSIVENESS, fn->lpr);
 120
 121         fn->private_data = pcd;
 122         fn->min_iqs = 2; /* 16 bit audio */
 123         pcd->current_gain = 1U << inertia;
 124         pcd->max_gain = 1U << (inertia + aggressiveness);
 125 }
 126
 127 const struct filter lsg_filter_cmd_com_compress_user_data = {
 128         .open = compress_open,
 129         .close = compress_close,
 130         .pre_select = generic_filter_pre_select,
 131         .post_select = compress_post_select,
 132 };