2 * Copyright (C) 2008 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file amp.c Paraslash's amplify filter. */
10 #include "amp_filter.cmdline.h"
17 /** The size of the output data buffer. */
18 #define AMP_CHUNK_SIZE 40960
20 extern char *stat_item_values[NUM_STAT_ITEMS];
22 /** Data specific to the amplify filter. */
23 struct private_amp_data {
24 /** Points to the configuration data for this instance of this filter. */
25 struct amp_filter_args_info *conf;
26 /** Amplification factor. */
30 static ssize_t amp_convert(char *inbuf, size_t inbuf_len, struct filter_node *fn)
32 size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
33 (fn->bufsize - fn->loaded) / 2 * 2);
34 struct private_amp_data *pad = fn->private_data;
35 int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
39 for (i = 0; i < length / 2; i++) {
40 int x = (PARA_ABS(*ip) * (64 + pad->amp)) >> 6;
41 *op++ = *ip++ > 0? PARA_MIN(x, 32767) : PARA_MAX(-x, -32768);
47 static void amp_close(struct filter_node *fn)
49 free(fn->private_data);
53 static void *amp_parse_config(int argc, char **argv)
55 struct amp_filter_args_info *conf = para_calloc(sizeof(*conf));
57 if (amp_cmdline_parser(argc, argv, conf))
59 if (conf->amp_arg < 0)
61 PARA_NOTICE_LOG("amplification: %u (scaling factor: %1.2f)\n", conf->amp_arg,
62 conf->amp_arg / 64.0 + 1.0);
69 static void amp_open(struct filter_node *fn)
71 struct private_amp_data *pad = para_calloc(sizeof(*pad));
74 fn->private_data = pad;
75 if (!pad->conf->amp_given && stat_item_values[SI_AMPLIFICATION]) {
76 int i = SI_AMPLIFICATION;
77 char *s = stat_item_values[i] + strlen(status_item_list[i]) + 1;
78 sscanf(s, "%u", &pad->amp);
80 pad->amp = pad->conf->amp_arg;
81 fn->bufsize = AMP_CHUNK_SIZE;
82 fn->buf = para_malloc(fn->bufsize);
86 * The init function of the amplify filter.
88 * \param f Pointer to the struct to initialize.
90 void amp_init(struct filter *f)
94 f->convert = amp_convert;
95 f->print_help = amp_cmdline_parser_print_help;
96 f->parse_config = amp_parse_config;