libmpeg3/audio/pcm.c

   1 #include "mpeg3private.h"
   2 #include "mpeg3protos.h"
   3
   4 #include <stdlib.h>
   5
   6
   7 mpeg3_pcm_t* mpeg3_new_pcm()
   8 {
   9         mpeg3_pcm_t *result = calloc(1, sizeof(mpeg3_pcm_t));
  10         return result;
  11 }
  12
  13
  14
  15 void mpeg3_delete_pcm(mpeg3_pcm_t *audio)
  16 {
  17         free(audio);
  18 }
  19
  20
  21 int mpeg3_pcm_check(unsigned char *header)
  22 {
  23         if(header[0] == ((MPEG3_PCM_START_CODE & 0xff000000) >> 24) &&
  24                 header[1] == ((MPEG3_PCM_START_CODE & 0xff0000) >> 16) &&
  25                 header[2] == ((MPEG3_PCM_START_CODE & 0xff00) >> 8) &&
  26                 header[3] == (MPEG3_PCM_START_CODE & 0xff))
  27                 return 0;
  28         else
  29                 return 1;
  30 }
  31
  32
  33
  34
  35 int mpeg3_pcm_header(mpeg3_pcm_t *audio, unsigned char *data)
  36 {
  37         if(mpeg3_pcm_check(data)) return 0;
  38
  39 /* Custom header generated by the demuxer */
  40         audio->samplerate = *(int32_t*)(data + 4);
  41         audio->bits = *(int32_t*)(data + 8);
  42         audio->channels = *(int32_t*)(data + 12);
  43         audio->framesize = *(int32_t*)(data + 16);
  44
  45         return audio->framesize;
  46 }
  47
  48 int mpeg3audio_dopcm(mpeg3_pcm_t *audio,
  49         char *frame,
  50         int frame_size,
  51         float **output,
  52         int render)
  53 {
  54         int bytes_per_sample = audio->bits / 8 * audio->channels;
  55         int output_size = (frame_size - PCM_HEADERSIZE) / bytes_per_sample;
  56         int i, j;
  57 //printf("mpeg3audio_dopcm 2 %d\n", frame_size);
  58
  59         if(render)
  60         {
  61                 for(i = 0; i < audio->channels; i++)
  62                 {
  63 //printf("mpeg3audio_dopcm 3\n");
  64                         float *output_channel = output[i];
  65 //printf("mpeg3audio_dopcm 4\n");
  66                         switch(audio->bits)
  67                         {
  68                                 case 16:
  69                                 {
  70 //printf("mpeg3audio_dopcm 5\n");
  71                                         unsigned char *input = frame +
  72                                                 PCM_HEADERSIZE +
  73                                                 audio->bits / 8 * i;
  74                                                 int16_t sample;
  75 //printf("mpeg3audio_dopcm 6\n");
  76                                         for(j = 0; j < output_size; j++)
  77                                         {
  78                                                 sample = ((int16_t)(input[0])) << 8;
  79                                                 sample |= input[1];
  80                                                 *output_channel = (float)sample / 32767.0;
  81                                                 input += bytes_per_sample;
  82                                                 output_channel++;
  83                                         }
  84 //printf("mpeg3audio_dopcm 7\n");
  85                                 }
  86                                         break;
  87                         }
  88                 }
  89         }
  90
  91 /*
  92  * printf("mpeg3audio_dopcm 2 %02x%02x%02x%02x\n",
  93  * *(unsigned char*)(frame + PCM_HEADERSIZE + 0),
  94  * *(unsigned char*)(frame + PCM_HEADERSIZE + 1),
  95  * *(unsigned char*)(frame + PCM_HEADERSIZE + 2),
  96  * *(unsigned char*)(frame + PCM_HEADERSIZE + 3));
  97  */
  98
  99         return output_size;
 100 }