libmpeg3/audio/ac3.c

   1 #include <stdint.h>
   2 #include <stdio.h>
   3
   4 #include <a52dec/a52.h>
   5 #include "mpeg3private.h"
   6 #include "mpeg3protos.h"
   7
   8 #include <string.h>
   9
  10
  11 mpeg3_ac3_t* mpeg3_new_ac3()
  12 {
  13         mpeg3_ac3_t *result = calloc(1, sizeof(mpeg3_ac3_t));
  14         result->stream = mpeg3bits_new_stream(0, 0);
  15         result->state = a52_init(0);
  16         result->output = a52_samples(result->state);
  17         return result;
  18 }
  19
  20 void mpeg3_delete_ac3(mpeg3_ac3_t *audio)
  21 {
  22         mpeg3bits_delete_stream(audio->stream);
  23         a52_free(audio->state);
  24         free(audio);
  25 }
  26
  27
  28 /* Return 1 if it isn't an AC3 header */
  29 int mpeg3_ac3_check(unsigned char *header)
  30 {
  31         int flags, samplerate, bitrate;
  32         return !a52_syncinfo(header,
  33                 &flags,
  34                 &samplerate,
  35                 &bitrate);
  36 }
  37
  38 /* Decode AC3 header */
  39 int mpeg3_ac3_header(mpeg3_ac3_t *audio, unsigned char *header)
  40 {
  41         int result = 0;
  42         audio->flags = 0;
  43
  44 //printf("mpeg3_ac3_header %02x%02x%02x%02x%02x%02x%02x%02x\n", header[0], header[1], header[2], header[3], header[4], header[5], header[6], header[7]);
  45         result = a52_syncinfo(header,
  46                 &audio->flags,
  47         &audio->samplerate,
  48                 &audio->bitrate);
  49
  50
  51         if(result)
  52         {
  53 //printf("%d\n", result);
  54                 audio->framesize = result;
  55                 audio->channels = 0;
  56
  57                 if(audio->flags & A52_LFE)
  58                         audio->channels++;
  59 /*
  60  * printf("mpeg3_ac3_header %08x %08x\n",
  61  * audio->flags & A52_LFE,
  62  * audio->flags & A52_CHANNEL_MASK);
  63  */
  64                 switch(audio->flags & A52_CHANNEL_MASK)
  65                 {
  66                         case A52_CHANNEL:
  67                                 audio->channels++;
  68                                 break;
  69                         case A52_MONO:
  70                                 audio->channels++;
  71                                 break;
  72                         case A52_STEREO:
  73                                 audio->channels += 2;
  74                                 break;
  75                         case A52_3F:
  76                                 audio->channels += 3;
  77                                 break;
  78                         case A52_2F1R:
  79                                 audio->channels += 3;
  80                                 break;
  81                         case A52_3F1R:
  82                                 audio->channels += 4;
  83                                 break;
  84                         case A52_2F2R:
  85                                 audio->channels += 4;
  86                                 break;
  87                         case A52_3F2R:
  88                                 audio->channels += 5;
  89                                 break;
  90                         case A52_DOLBY:
  91                                 audio->channels += 2;
  92                                 break;
  93                         default:
  94                                 printf("mpeg3_ac3_header: unknown channel code: %p\n", audio->flags & A52_CHANNEL_MASK);
  95                                 break;
  96                 }
  97         }
  98 //printf("mpeg3_ac3_header 1 %d\n", audio->channels);
  99         return result;
 100 }
 101
 102
 103 int mpeg3audio_doac3(mpeg3_ac3_t *audio,
 104         char *frame,
 105         int frame_size,
 106         float **output,
 107         int render)
 108 {
 109         int output_position = 0;
 110         sample_t level = 1;
 111         int i, j, k, l;
 112
 113 //printf("mpeg3audio_doac3 1\n");
 114         a52_frame(audio->state,
 115                 frame,
 116                 &audio->flags,
 117                 &level,
 118                 0);
 119 //printf("mpeg3audio_doac3 2\n");
 120         a52_dynrng(audio->state, NULL, NULL);
 121 //printf("mpeg3audio_doac3 3\n");
 122         for(i = 0; i < 6; i++)
 123         {
 124                 if(!a52_block(audio->state))
 125                 {
 126                         l = 0;
 127                         if(render)
 128                         {
 129 // Remap the channels to conform to encoders.
 130                                 for(j = 0; j < audio->channels; j++)
 131                                 {
 132                                         int dst_channel = j;
 133
 134 // Make LFE last channel.
 135 // Shift all other channels down 1.
 136                                         if((audio->flags & A52_LFE))
 137                                         {
 138                                                 if(j == 0)
 139                                                         dst_channel = audio->channels - 1;
 140                                                 else
 141                                                         dst_channel--;
 142                                         }
 143
 144 // Swap front left and center for certain configurations
 145                                         switch(audio->flags & A52_CHANNEL_MASK)
 146                                         {
 147                                                 case A52_3F:
 148                                                 case A52_3F1R:
 149                                                 case A52_3F2R:
 150                                                         if(dst_channel == 0) dst_channel = 1;
 151                                                         else
 152                                                         if(dst_channel == 1) dst_channel = 0;
 153                                                         break;
 154                                         }
 155
 156                                         for(k = 0; k < 256; k++)
 157                                         {
 158                                                 output[dst_channel][output_position + k] = ((sample_t*)audio->output)[l];
 159                                                 l++;
 160                                         }
 161                                 }
 162                         }
 163                         output_position += 256;
 164                 }
 165         }
 166
 167
 168         return output_position;
 169 }
 170
 171
 172