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 int amp_parse_config(int argc, char **argv, void **config)
  54 {
  55         struct amp_filter_args_info *amp_conf = para_calloc(sizeof(*amp_conf));
  56         int ret = -E_AMP_SYNTAX;
  57
  58         if (amp_cmdline_parser(argc, argv, amp_conf))
  59                 goto err;
  60         ret = -ERRNO_TO_PARA_ERROR(EINVAL);
  61         if (amp_conf->amp_arg < 0)
  62                 goto err;
  63         PARA_NOTICE_LOG("amplification: %u (scaling factor: %1.2f)\n",
  64                 amp_conf->amp_arg, amp_conf->amp_arg / 64.0 + 1.0);
  65         *config = amp_conf;
  66         return 1;
  67 err:
  68         free(amp_conf);
  69         return ret;
  70 }
  71
  72 static void amp_open(struct filter_node *fn)
  73 {
  74         struct private_amp_data *pad = para_calloc(sizeof(*pad));
  75
  76         pad->conf = fn->conf;
  77         fn->private_data = pad;
  78         if (!pad->conf->amp_given && stat_item_values[SI_AMPLIFICATION]) {
  79                 int i = SI_AMPLIFICATION;
  80                 char *s = stat_item_values[i] + strlen(status_item_list[i]) + 1;
  81                 sscanf(s, "%u", &pad->amp);
  82         } else
  83                 pad->amp = pad->conf->amp_arg;
  84         fn->bufsize = AMP_CHUNK_SIZE;
  85         fn->buf = para_malloc(fn->bufsize);
  86 }
  87
  88 /**
  89  * The init function of the amplify filter.
  90  *
  91  * \param f Pointer to the struct to initialize.
  92  */
  93 void amp_init(struct filter *f)
  94 {
  95         f->open = amp_open;
  96         f->close = amp_close;
  97         f->convert = amp_convert;
  98         f->print_help = amp_cmdline_parser_print_help;
  99         f->parse_config = amp_parse_config;
 100 }