2 * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file compress_filter.c Paraslash's dynamic audio range compressor. */
10 * Uses ideas of AudioCompress, (C) 2002-2004 M. Hari Nezumi <magenta@trikuare.cx>
16 #include "compress_filter.cmdline.h"
20 #include "buffer_tree.h"
25 /** Data specific to the compress filter. */
26 struct private_compress_data {
27 /** The current multiplier. */
28 unsigned current_gain;
29 /** Points to the configuration data for this instance of the compress filter. */
30 struct compress_filter_args_info *conf;
31 /** Maximal admissible gain. */
33 /** Number of samples already seen. */
35 /** Absolute value of the maximal sample in the current block. */
39 static void compress_close(struct filter_node *fn)
41 free(fn->private_data);
44 static int compress_post_select(__a_unused struct sched *s, void *context)
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);
54 unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
55 mask = (1 << pcd->conf->blocksize_arg) - 1;
59 ret = btr_node_status(btrn, fn->min_iqs, BTR_NT_INTERNAL);
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;
70 ip = (int16_t *)inbuf;
74 op = para_malloc(length);
75 for (i = 0; i < length / 2; i++) {
76 /* be careful in that heat, my dear */
84 sample *= pcd->current_gain;
85 sample >>= gain_shift;
86 if (sample > 32767) { /* clip */
88 pcd->current_gain = (3 * pcd->current_gain +
89 (1 << pcd->conf->inertia_arg)) / 4;
91 } else if (sample > pcd->peak)
93 op[i] = neg? -sample : sample;
94 if (++pcd->num_samples & mask)
96 // PARA_DEBUG_LOG("gain: %u, peak: %u\n", pcd->current_gain,
98 if (pcd->peak < pcd->conf->target_level_arg) {
99 if (pcd->current_gain < pcd->max_gain)
102 pcd->current_gain = PARA_MAX(pcd->current_gain - 2,
103 1U << pcd->conf->inertia_arg);
107 btr_pushdown_one(btrn);
109 btr_consume(btrn, length);
110 btr_add_output((char *)op, length, btrn);
115 btr_remove_node(&fn->btrn);
119 /** TODO: Add sanity checks */
120 static int compress_parse_config(int argc, char **argv, void **config)
122 struct compress_filter_args_info *conf = para_calloc(sizeof(*conf));
124 compress_filter_cmdline_parser(argc, argv, conf);
129 static void compress_open(struct filter_node *fn)
131 struct private_compress_data *pcd = para_calloc(
132 sizeof(struct private_compress_data));
133 pcd->conf = fn->conf;
134 fn->private_data = pcd;
135 fn->min_iqs = 2; /* 16 bit audio */
136 pcd->current_gain = 1 << pcd->conf->inertia_arg;
137 pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
140 static void compress_free_config(void *conf)
142 compress_filter_cmdline_parser_free(conf);
146 * The init function of the compress filter.
148 * \param f Pointer to the struct to initialize.
150 void compress_filter_init(struct filter *f)
152 struct compress_filter_args_info dummy;
154 compress_filter_cmdline_parser_init(&dummy);
155 f->open = compress_open;
156 f->close = compress_close;
157 f->pre_select = generic_filter_pre_select;
158 f->post_select = compress_post_select;
159 f->parse_config = compress_parse_config;
160 f->free_config = compress_free_config;
161 f->help = (struct ggo_help)DEFINE_GGO_HELP(compress_filter);