compress_filter.c

   1 /*
   2  * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
   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 <regex.h>
  14 #include <lopsub.h>
  15
  16 #include "filter_cmd.lsg.h"
  17 #include "para.h"
  18 #include "list.h"
  19 #include "sched.h"
  20 #include "buffer_tree.h"
  21 #include "filter.h"
  22 #include "string.h"
  23 #include "error.h"
  24
  25 #define U32_OPTVAL(_opt, _lpr) (FILTER_CMD_OPT_UINT32_VAL(COMPRESS, _opt, _lpr))
  26
  27 /** Data specific to the compress filter. */
  28 struct private_compress_data {
  29         /** The current multiplier. */
  30         unsigned current_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         int peak;
  37 };
  38
  39 static void compress_close(struct filter_node *fn)
  40 {
  41         free(fn->private_data);
  42 }
  43
  44 static int compress_post_select(__a_unused struct sched *s, void *context)
  45 {
  46         struct filter_node *fn = context;
  47         struct private_compress_data *pcd = fn->private_data;
  48         struct btr_node *btrn = fn->btrn;
  49         bool inplace = btr_inplace_ok(btrn);
  50         int ret;
  51         char *inbuf;
  52         size_t length, i;
  53         int16_t *ip, *op;
  54         uint32_t inertia = U32_OPTVAL(INERTIA, fn->lpr);
  55         unsigned gain_shift = inertia + U32_OPTVAL(DAMP, fn->lpr),
  56                 mask = (1 << U32_OPTVAL(BLOCKSIZE, fn->lpr)) - 1;
  57         //inplace = false;
  58 next_buffer:
  59         ret = btr_node_status(btrn, fn->min_iqs, BTR_NT_INTERNAL);
  60         if (ret < 0)
  61                 goto err;
  62         if (ret == 0)
  63                 return 0;
  64         btr_merge(btrn, fn->min_iqs);
  65         length = btr_next_buffer(btrn, &inbuf) & ~(size_t)1;
  66         if (length == 0) { /* eof and 1 byte available */
  67                 ret = -E_COMPRESS_EOF;
  68                 goto err;
  69         }
  70         ip = (int16_t *)inbuf;
  71         if (inplace)
  72                 op = ip;
  73         else
  74                 op = para_malloc(length);
  75         for (i = 0; i < length / 2; i++) {
  76                 /* be careful in that heat, my dear */
  77                 int sample = *ip++;
  78                 bool neg = false;
  79
  80                 if (sample < 0) {
  81                         sample = -sample;
  82                         neg = true;
  83                 }
  84                 sample *= pcd->current_gain;
  85                 sample >>= gain_shift;
  86                 if (sample > 32767) { /* clip */
  87                         sample = 32767;
  88                         pcd->current_gain = (3 * pcd->current_gain +
  89                                 (1 << inertia)) / 4;
  90                         pcd->peak = 0;
  91                 } else if (sample > pcd->peak)
  92                         pcd->peak = sample;
  93                 op[i] = neg? -sample : sample;
  94                 if (++pcd->num_samples & mask)
  95                         continue;
  96 //              PARA_DEBUG_LOG("gain: %u, peak: %u\n", pcd->current_gain,
  97 //                      pcd->peak);
  98                 if (pcd->peak < U32_OPTVAL(TARGET_LEVEL, fn->lpr)) {
  99                         if (pcd->current_gain < pcd->max_gain)
 100                                 pcd->current_gain++;
 101                 } else
 102                         pcd->current_gain = PARA_MAX(pcd->current_gain - 2,
 103                                 1U << inertia);
 104                 pcd->peak = 0;
 105         }
 106         if (inplace)
 107                 btr_pushdown_one(btrn);
 108         else {
 109                 btr_consume(btrn, length);
 110                 btr_add_output((char *)op, length, btrn);
 111         }
 112         goto next_buffer;
 113 err:
 114         assert(ret < 0);
 115         btr_remove_node(&fn->btrn);
 116         return ret;
 117 }
 118
 119 static void compress_open(struct filter_node *fn)
 120 {
 121         struct private_compress_data *pcd = para_calloc(sizeof(*pcd));
 122         uint32_t inertia = U32_OPTVAL(INERTIA, fn->lpr);
 123         uint32_t aggressiveness = U32_OPTVAL(AGGRESSIVENESS, fn->lpr);
 124
 125         fn->private_data = pcd;
 126         fn->min_iqs = 2; /* 16 bit audio */
 127         pcd->current_gain = 1U << inertia;
 128         pcd->max_gain = 1U << (inertia + aggressiveness);
 129 }
 130
 131 const struct filter lsg_filter_cmd_com_compress_user_data = {
 132         .open = compress_open,
 133         .close = compress_close,
 134         .pre_select = generic_filter_pre_select,
 135         .post_select = compress_post_select,
 136 };