quicktime/vbraudio.c

   1 // Utility functions for vbr audio
   2
   3 #include "funcprotos.h"
   4 #include "quicktime.h"
   5
   6
   7
   8 // Maximum samples to store in output buffer
   9 #define MAX_VBR_BUFFER 0x200000
  10
  11
  12
  13 void quicktime_init_vbr(quicktime_vbr_t *ptr, int channels)
  14 {
  15         ptr->channels = channels;
  16         if(!ptr->output_buffer)
  17         {
  18                 int i;
  19                 ptr->output_buffer = calloc(channels, sizeof(double*));
  20                 for(i = 0; i < channels; i++)
  21                         ptr->output_buffer[i] = calloc(MAX_VBR_BUFFER, sizeof(double));
  22         }
  23 }
  24
  25 void quicktime_clear_vbr(quicktime_vbr_t *ptr)
  26 {
  27         int i;
  28
  29         if(ptr->output_buffer)
  30         {
  31                 for(i = 0; i < ptr->channels; i++)
  32                         free(ptr->output_buffer[i]);
  33                 free(ptr->output_buffer);
  34         }
  35
  36         if(ptr->input_buffer)
  37         {
  38                 free(ptr->input_buffer);
  39         }
  40 }
  41
  42 void quicktime_vbr_set_channels(quicktime_vbr_t *ptr, int channels)
  43 {
  44         ptr->channels = channels;
  45 }
  46
  47 int64_t quicktime_vbr_end(quicktime_vbr_t *ptr)
  48 {
  49         return ptr->buffer_end;
  50 }
  51
  52 unsigned char* quicktime_vbr_input(quicktime_vbr_t *ptr)
  53 {
  54         return ptr->input_buffer;
  55 }
  56
  57 int quicktime_vbr_input_size(quicktime_vbr_t *ptr)
  58 {
  59         return ptr->input_size;
  60 }
  61
  62 static int limit_samples(int samples)
  63 {
  64         if(samples > MAX_VBR_BUFFER)
  65         {
  66                 fprintf(stderr,
  67                         "quicktime_align_vbr: can't decode more than %p samples at a time.\n",
  68                         MAX_VBR_BUFFER);
  69                 return 1;
  70         }
  71         return 0;
  72 }
  73
  74 int quicktime_align_vbr(quicktime_audio_map_t *atrack,
  75         int samples)
  76 {
  77         quicktime_vbr_t *ptr = &atrack->vbr;
  78         int64_t start_position = atrack->current_position;
  79
  80         if(limit_samples(samples)) return 1;
  81
  82 // Desired start point is outside existing range.  Reposition buffer pointer
  83 // to start time of nearest frame.
  84         if(start_position < ptr->buffer_end - ptr->buffer_size ||
  85                 start_position > ptr->buffer_end)
  86         {
  87                 int64_t start_time = start_position;
  88                 ptr->sample = quicktime_time_to_sample(&atrack->track->mdia.minf.stbl.stts,
  89                         &start_time);
  90                 ptr->buffer_end = start_time;
  91                 ptr->buffer_size = 0;
  92         }
  93
  94         return 0;
  95 }
  96
  97 int quicktime_read_vbr(quicktime_t *file,
  98         quicktime_audio_map_t *atrack)
  99 {
 100         quicktime_vbr_t *vbr = &atrack->vbr;
 101         quicktime_trak_t *trak = atrack->track;
 102         int64_t offset = quicktime_sample_to_offset(file,
 103                 trak,
 104                 vbr->sample);
 105         int size = quicktime_sample_size(trak, vbr->sample);
 106         int new_allocation = vbr->input_size + size;
 107         int result = 0;
 108
 109         if(vbr->input_allocation < new_allocation)
 110         {
 111                 vbr->input_buffer = realloc(vbr->input_buffer, new_allocation);
 112                 vbr->input_allocation = new_allocation;
 113         }
 114
 115
 116         quicktime_set_position(file, offset);
 117         result = !quicktime_read_data(file, vbr->input_buffer + vbr->input_size, size);
 118         vbr->input_size += size;
 119         vbr->sample++;
 120         return result;
 121 }
 122
 123 void quicktime_shift_vbr(quicktime_audio_map_t *atrack, int bytes)
 124 {
 125         quicktime_vbr_t *vbr = &atrack->vbr;
 126         if(bytes >= vbr->input_size)
 127         {
 128                 vbr->input_size = 0;
 129         }
 130         else
 131         {
 132                 int i, j;
 133                 for(i = 0, j = bytes; j < vbr->input_size; i++, j++)
 134                         vbr->input_buffer[i] = vbr->input_buffer[j];
 135                 vbr->input_size -= bytes;
 136         }
 137 }
 138
 139 void quicktime_store_vbr_float(quicktime_audio_map_t *atrack,
 140         float *samples,
 141         int sample_count)
 142 {
 143         int i, j;
 144         quicktime_vbr_t *vbr = &atrack->vbr;
 145         for(i = 0; i < sample_count; i++)
 146         {
 147                 for(j = 0; j < vbr->channels; j++)
 148                 {
 149                         vbr->output_buffer[j][vbr->buffer_ptr] =
 150                                 samples[i * vbr->channels + j];
 151                 }
 152                 vbr->buffer_ptr++;
 153                 if(vbr->buffer_ptr >= MAX_VBR_BUFFER)
 154                         vbr->buffer_ptr = 0;
 155         }
 156         vbr->buffer_end += sample_count;
 157         vbr->buffer_size += sample_count;
 158         if(vbr->buffer_size > MAX_VBR_BUFFER) vbr->buffer_size = MAX_VBR_BUFFER;
 159 }
 160
 161 void quicktime_copy_vbr_float(quicktime_vbr_t *vbr,
 162         int64_t start_position,
 163         int samples,
 164         float *output,
 165         int channel)
 166 {
 167         int i, j;
 168         int input_ptr = vbr->buffer_ptr -
 169                 (vbr->buffer_end - start_position);
 170         while(input_ptr < 0) input_ptr += MAX_VBR_BUFFER;
 171
 172         for(i = 0; i < samples; i++)
 173         {
 174                 output[i] = vbr->output_buffer[channel][input_ptr++];
 175                 if(input_ptr >= MAX_VBR_BUFFER)
 176                         input_ptr = 0;
 177         }
 178 }
 179
 180
 181 void quicktime_copy_vbr_int16(quicktime_vbr_t *vbr,
 182         int64_t start_position,
 183         int samples,
 184         int16_t *output,
 185         int channel)
 186 {
 187         int i, j;
 188         int input_ptr = vbr->buffer_ptr -
 189                 (vbr->buffer_end - start_position);
 190         while(input_ptr < 0) input_ptr += MAX_VBR_BUFFER;
 191
 192         for(i = 0; i < samples; i++)
 193         {
 194                 output[i] = (int)(vbr->output_buffer[channel][input_ptr++] * 32767);
 195                 if(input_ptr >= MAX_VBR_BUFFER)
 196                         input_ptr = 0;
 197         }
 198 }
 199
 200
 201