compress.c: Simplify volume adjusting code.
[paraslash.git] / 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 /** Minimal admissible gain. */
30 unsigned min_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 unsigned peak;
37 };
38
39 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
40 {
41 size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
42 (fn->bufsize - fn->loaded) / 2 * 2);
43 struct private_compress_data *pcd = fn->private_data;
44 int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
45 unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
46 mask = (1 << pcd->conf->blocksize_arg) - 1;
47
48 if (!length)
49 return 0;
50 for (i = 0; i < length / 2; i++) {
51 /* be careful in that heat, my dear */
52 int sample = *ip++, adjusted_sample;
53
54 adjusted_sample = (PARA_ABS(sample) * pcd->current_gain)
55 >> gain_shift;
56 if (unlikely(adjusted_sample > 32767)) { /* clip */
57 PARA_NOTICE_LOG("clip: sample: %d, adjusted sample: %d\n",
58 sample, adjusted_sample);
59 adjusted_sample = 32767;
60 pcd->current_gain = (3 * pcd->current_gain +
61 (1 << pcd->conf->inertia_arg)) / 4;
62 pcd->peak = 0;
63 } else
64 pcd->peak = PARA_MAX(pcd->peak, adjusted_sample);
65 *op++ = sample >= 0? adjusted_sample : -adjusted_sample;
66 if (likely(++pcd->num_samples & mask))
67 continue;
68 if (pcd->peak < pcd->conf->target_level_arg) {
69 if (pcd->current_gain < pcd->max_gain)
70 pcd->current_gain++;
71 } else {
72 if (pcd->current_gain > pcd->min_gain + 1)
73 pcd->current_gain -= 2;
74 }
75 PARA_DEBUG_LOG("gain: %lu, peak: %d\n", pcd->current_gain,
76 pcd->peak);
77 pcd->peak = 0;
78 }
79 fn->loaded += length;
80 return length;
81 }
82
83 static void close_compress(struct filter_node *fn)
84 {
85 free(fn->private_data);
86 free(fn->buf);
87 }
88
89 static void *compress_parse_config(int argc, char **argv)
90 {
91 struct compress_filter_args_info *ret = para_calloc(sizeof(struct compress_filter_args_info));
92 if (!compress_cmdline_parser(argc, argv, ret))
93 return ret;
94 free(ret);
95 return NULL;
96 }
97
98 static void open_compress(struct filter_node *fn)
99 {
100 struct private_compress_data *pcd = para_calloc(
101 sizeof(struct private_compress_data));
102 pcd->conf = fn->conf;
103 fn->private_data = pcd;
104 fn->bufsize = COMPRESS_CHUNK_SIZE;
105 fn->buf = para_malloc(fn->bufsize);
106 pcd->current_gain = 1 << pcd->conf->inertia_arg;
107 pcd->min_gain = 1 << (pcd->conf->inertia_arg - pcd->conf->aggressiveness_arg);
108 pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
109 }
110
111 /**
112 * The init function of the compress filter.
113 *
114 * \param f Pointer to the struct to initialize.
115 */
116 void compress_init(struct filter *f)
117 {
118 f->open = open_compress;
119 f->close = close_compress;
120 f->convert = compress;
121 f->print_help = compress_cmdline_parser_print_help;
122 f->parse_config = compress_parse_config;
123 }