src/pcm_float_converter.c

   1 /*
   2  * Copyright (C) 2013 nu774
   3  * For conditions of distribution and use, see copyright notice in COPYING
   4  */
   5 #if HAVE_CONFIG_H
   6 #  include "config.h"
   7 #endif
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #if HAVE_STDINT_H
  11 #  include <stdint.h>
  12 #endif
  13 #include "pcm_reader.h"
  14
  15 typedef struct pcm_float_converter_t {
  16     pcm_reader_vtbl_t *vtbl;
  17     pcm_reader_t *src;
  18     pcm_sample_description_t format;
  19 } pcm_float_converter_t;
  20
  21 static inline pcm_reader_t *get_source(pcm_reader_t *reader)
  22 {
  23     return ((pcm_float_converter_t *)reader)->src;
  24 }
  25
  26 static const
  27 pcm_sample_description_t *get_format(pcm_reader_t *reader)
  28 {
  29     return &((pcm_float_converter_t *)reader)->format;
  30 }
  31
  32 static int64_t get_length(pcm_reader_t *reader)
  33 {
  34     return pcm_get_length(get_source(reader));
  35 }
  36
  37 static int64_t get_position(pcm_reader_t *reader)
  38 {
  39     return pcm_get_position(get_source(reader));
  40 }
  41
  42 static int read_frames(pcm_reader_t *reader, void *buffer, unsigned nframes)
  43 {
  44     unsigned i;
  45     pcm_float_converter_t *self = (pcm_float_converter_t *)reader;
  46     const pcm_sample_description_t *sfmt = pcm_get_format(self->src);
  47     nframes = pcm_read_frames(self->src, buffer, nframes);
  48     if (!(sfmt->sample_type & PCM_TYPE_FLOAT)) {
  49         int32_t *ip = buffer;
  50         float   *op = buffer;
  51         unsigned i, count = nframes * sfmt->channels_per_frame;
  52         for (i = 0; i < count; ++i)
  53             op[i] = ip[i] / 2147483648.0f;
  54     }
  55     return nframes;
  56 }
  57
  58 static void teardown(pcm_reader_t **reader)
  59 {
  60     pcm_float_converter_t *self = (pcm_float_converter_t *)*reader;
  61     pcm_teardown(&self->src);
  62     free(self);
  63     *reader = 0;
  64 }
  65
  66 static pcm_reader_vtbl_t my_vtable = {
  67     get_format, get_length, get_position, read_frames, teardown
  68 };
  69
  70 pcm_reader_t *pcm_open_float_converter(pcm_reader_t *reader)
  71 {
  72     pcm_float_converter_t *self = 0;
  73     pcm_sample_description_t *fmt;
  74
  75     if ((self = calloc(1, sizeof(pcm_float_converter_t))) == 0)
  76         return 0;
  77     self->src = reader;
  78     self->vtbl = &my_vtable;
  79     memcpy(&self->format, pcm_get_format(reader), sizeof(self->format));
  80     fmt = &self->format;
  81     fmt->bits_per_channel = 32;
  82     fmt->sample_type = PCM_TYPE_FLOAT;
  83     fmt->bytes_per_frame = 4 * fmt->channels_per_frame;
  84     return (pcm_reader_t *)self;
  85 }