code.delx.au - pulseaudio/blob - src/sample.c

   1 #include <string.h>
   2 #include <assert.h>
   3
   4 #include "sample.h"
   5
   6 struct sample_spec default_sample_spec = {
   7     .format = SAMPLE_S16NE,
   8     .rate = 44100,
   9     .channels = 2
  10 };
  11
  12 struct memblock *silence(struct memblock* b, struct sample_spec *spec) {
  13     char c = 0;
  14     assert(b && spec);
  15     memblock_assert_exclusive(b);
  16
  17     switch (spec->format) {
  18         case SAMPLE_U8:
  19             c = 127;
  20             break;
  21         case SAMPLE_S16LE:
  22         case SAMPLE_S16BE:
  23         case SAMPLE_FLOAT32:
  24             c = 0;
  25             break;
  26         case SAMPLE_ALAW:
  27         case SAMPLE_ULAW:
  28             c = 80;
  29             break;
  30     }
  31
  32     memset(b->data, c, b->length);
  33     return b;
  34 }
  35
  36 void add_clip(struct memchunk *target, struct memchunk *chunk, struct sample_spec *spec) {
  37     int16_t *p, *d;
  38     size_t i;
  39     assert(target && target->memblock && chunk && chunk->memblock && spec);
  40     assert(spec->format == SAMPLE_S16NE);
  41     assert((target->length & 1) == 0);
  42
  43     d = target->memblock->data + target->index;
  44     p = chunk->memblock->data + chunk->index;
  45
  46     for (i = 0; i < target->length && i < chunk->length; i++) {
  47         int32_t r = (int32_t) *d + (int32_t) *p;
  48         if (r < -0x8000) r = 0x8000;
  49         if (r > 0x7FFF) r = 0x7FFF;
  50         *d = (int16_t) r;
  51     }
  52 }
  53
  54 size_t sample_size(struct sample_spec *spec) {
  55     assert(spec);
  56     size_t b = 1;
  57
  58     switch (spec->format) {
  59         case SAMPLE_U8:
  60         case SAMPLE_ULAW:
  61         case SAMPLE_ALAW:
  62             b = 1;
  63             break;
  64         case SAMPLE_S16LE:
  65         case SAMPLE_S16BE:
  66             b = 2;
  67             break;
  68         case SAMPLE_FLOAT32:
  69             b = 4;
  70             break;
  71     }
  72
  73     return b * spec->channels;
  74 }
  75
  76 size_t bytes_per_second(struct sample_spec *spec) {
  77     assert(spec);
  78     return spec->rate*sample_size(spec);
  79 }
  80