amp_filter.c

   1 /*
   2  * Copyright (C) 2008 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file amp_filter.c Paraslash's amplify filter. */
   8
   9 #include "para.h"
  10 #include "amp_filter.cmdline.h"
  11 #include "list.h"
  12 #include "sched.h"
  13 #include "filter.h"
  14 #include "string.h"
  15 #include "error.h"
  16
  17 /** The size of the output data buffer. */
  18 #define AMP_CHUNK_SIZE 40960
  19
  20 extern char *stat_item_values[NUM_STAT_ITEMS];
  21
  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. */
  27         unsigned amp;
  28 };
  29
  30 static ssize_t amp_convert(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  31 {
  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);
  36
  37         if (!length)
  38                 return 0;
  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);
  42         }
  43         fn->loaded += length;
  44         return length;
  45 }
  46
  47 static void amp_close(struct filter_node *fn)
  48 {
  49         free(fn->private_data);
  50         free(fn->buf);
  51 }
  52
  53 static void *amp_parse_config(int argc, char **argv)
  54 {
  55         struct amp_filter_args_info *conf = para_calloc(sizeof(*conf));
  56
  57         if (amp_cmdline_parser(argc, argv, conf))
  58                 goto err;
  59         if (conf->amp_arg < 0)
  60                 goto err;
  61         PARA_NOTICE_LOG("amplification: %u (scaling factor: %1.2f)\n", conf->amp_arg,
  62                 conf->amp_arg / 64.0 + 1.0);
  63         return conf;
  64 err:
  65         free(conf);
  66         return NULL;
  67 }
  68
  69 static void amp_open(struct filter_node *fn)
  70 {
  71         struct private_amp_data *pad = para_calloc(sizeof(*pad));
  72
  73         pad->conf = fn->conf;
  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);
  79         } else
  80                 pad->amp = pad->conf->amp_arg;
  81         fn->bufsize = AMP_CHUNK_SIZE;
  82         fn->buf = para_malloc(fn->bufsize);
  83 }
  84
  85 /**
  86  * The init function of the amplify filter.
  87  *
  88  * \param f Pointer to the struct to initialize.
  89  */
  90 void amp_init(struct filter *f)
  91 {
  92         f->open = amp_open;
  93         f->close = amp_close;
  94         f->convert = amp_convert;
  95         f->print_help = amp_cmdline_parser_print_help;
  96         f->parse_config = amp_parse_config;
  97 }