quicktime/ima4.c

   1 #include "funcprotos.h"
   2 #include "ima4.h"
   3 #include "quicktime.h"
   4
   5 typedef struct
   6 {
   7 /* During decoding the work_buffer contains the most recently read chunk. */
   8 /* During encoding the work_buffer contains interlaced overflow samples  */
   9 /* from the last chunk written. */
  10         int16_t *work_buffer;
  11         unsigned char *read_buffer;    /* Temporary buffer for drive reads. */
  12
  13 /* Starting information for all channels during encoding. */
  14         int *last_samples, *last_indexes;
  15         long chunk; /* Number of chunk in work buffer */
  16         int buffer_channel; /* Channel of work buffer */
  17
  18 /* Number of samples in largest chunk read. */
  19 /* Number of samples plus overflow in largest chunk write, interlaced. */
  20         long work_size;
  21         long work_overflow; /* Number of overflow samples from the last chunk written. */
  22         long read_size;     /* Size of read buffer. */
  23 } quicktime_ima4_codec_t;
  24
  25 static int ima4_step[89] =
  26 {
  27     7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
  28     19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
  29     50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
  30     130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
  31     337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
  32     876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
  33     2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
  34     5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
  35     15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
  36 };
  37
  38 static int ima4_index[16] =
  39 {
  40     -1, -1, -1, -1, 2, 4, 6, 8,
  41     -1, -1, -1, -1, 2, 4, 6, 8
  42 };
  43
  44 /* Known by divine revelation */
  45
  46 #define BLOCK_SIZE 0x22
  47 #define SAMPLES_PER_BLOCK 0x40
  48
  49 /* ================================== private for ima4 */
  50
  51
  52 void ima4_decode_sample(int *predictor, int *nibble, int *index, int *step)
  53 {
  54         int difference, sign;
  55
  56 /* Get new index value */
  57         *index += ima4_index[*nibble];
  58
  59         if(*index < 0) *index = 0;
  60         else
  61         if(*index > 88) *index = 88;
  62
  63 /* Get sign and magnitude from *nibble */
  64         sign = *nibble & 8;
  65         *nibble = *nibble & 7;
  66
  67 /* Get difference */
  68         difference = *step >> 3;
  69         if(*nibble & 4) difference += *step;
  70         if(*nibble & 2) difference += *step >> 1;
  71         if(*nibble & 1) difference += *step >> 2;
  72
  73 /* Predict value */
  74         if(sign)
  75         *predictor -= difference;
  76         else
  77         *predictor += difference;
  78
  79         if(*predictor > 32767) *predictor = 32767;
  80         else
  81         if(*predictor < -32768) *predictor = -32768;
  82
  83 /* Update the step value */
  84         *step = ima4_step[*index];
  85 }
  86
  87 void ima4_decode_block(quicktime_audio_map_t *atrack, int16_t *output, unsigned char *input)
  88 {
  89         int predictor;
  90         int index;
  91         int step;
  92         int i, nibble, nibble_count, block_size;
  93         unsigned char *block_ptr;
  94         unsigned char *input_end = input + BLOCK_SIZE;
  95         quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)atrack->codec)->priv;
  96
  97 /* Get the chunk header */
  98         predictor = *input++ << 8;
  99         predictor |= *input++;
 100
 101         index = predictor & 0x7f;
 102         if(index > 88) index = 88;
 103
 104         predictor &= 0xff80;
 105         if(predictor & 0x8000) predictor -= 0x10000;
 106         step = ima4_step[index];
 107
 108 /* Read the input buffer sequentially, one nibble at a time */
 109         nibble_count = 0;
 110         while(input < input_end)
 111         {
 112                 nibble = nibble_count ? (*input++  >> 4) & 0x0f : *input & 0x0f;
 113
 114                 ima4_decode_sample(&predictor, &nibble, &index, &step);
 115                 *output++ = predictor;
 116
 117                 nibble_count ^= 1;
 118         }
 119 }
 120
 121
 122 void ima4_encode_sample(int *last_sample, int *last_index, int *nibble, int next_sample)
 123 {
 124         int difference, new_difference, mask, step;
 125
 126         difference = next_sample - *last_sample;
 127         *nibble = 0;
 128         step = ima4_step[*last_index];
 129         new_difference = step >> 3;
 130
 131         if(difference < 0)
 132         {
 133                 *nibble = 8;
 134                 difference = -difference;
 135         }
 136
 137         mask = 4;
 138         while(mask)
 139         {
 140                 if(difference >= step)
 141                 {
 142                         *nibble |= mask;
 143                         difference -= step;
 144                         new_difference += step;
 145                 }
 146
 147                 step >>= 1;
 148                 mask >>= 1;
 149         }
 150
 151         if(*nibble & 8)
 152                 *last_sample -= new_difference;
 153         else
 154                 *last_sample += new_difference;
 155
 156         if(*last_sample > 32767) *last_sample = 32767;
 157         else
 158         if(*last_sample < -32767) *last_sample = -32767;
 159
 160         *last_index += ima4_index[*nibble];
 161
 162         if(*last_index < 0) *last_index = 0;
 163         else
 164         if(*last_index > 88) *last_index= 88;
 165 }
 166
 167 void ima4_encode_block(quicktime_audio_map_t *atrack, unsigned char *output, int16_t *input, int step, int channel)
 168 {
 169         quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)atrack->codec)->priv;
 170         int i, nibble_count = 0, nibble, header;
 171
 172 /* Get a fake starting sample */
 173         header = codec->last_samples[channel];
 174 /* Force rounding. */
 175         if(header < 0x7fc0) header += 0x40;
 176         if(header < 0) header += 0x10000;
 177         header &= 0xff80;
 178         *output++ = (header & 0xff00) >> 8;
 179         *output++ = (header & 0x80) + (codec->last_indexes[channel] & 0x7f);
 180
 181         for(i = 0; i < SAMPLES_PER_BLOCK; i++)
 182         {
 183                 ima4_encode_sample(&(codec->last_samples[channel]),
 184                                                         &(codec->last_indexes[channel]),
 185                                                         &nibble,
 186                                                         *input);
 187
 188                 if(nibble_count)
 189                         *output++ |= (nibble << 4);
 190                 else
 191                         *output = nibble;
 192
 193                 input += step;
 194                 nibble_count ^= 1;
 195         }
 196 }
 197
 198 /* Convert the number of samples in a chunk into the number of bytes in that */
 199 /* chunk.  The number of samples in a chunk should end on a block boundary. */
 200 long ima4_samples_to_bytes(long samples, int channels)
 201 {
 202         long bytes = samples / SAMPLES_PER_BLOCK * BLOCK_SIZE * channels;
 203         return bytes;
 204 }
 205
 206 /* Decode the chunk into the work buffer */
 207 int ima4_decode_chunk(quicktime_t *file, int track, long chunk, int channel)
 208 {
 209         int result = 0;
 210         int i, j;
 211         long chunk_samples, chunk_bytes;
 212         unsigned char *chunk_ptr, *block_ptr;
 213         quicktime_trak_t *trak = file->atracks[track].track;
 214         quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)file->atracks[track].codec)->priv;
 215
 216 /* Get the byte count to read. */
 217         chunk_samples = quicktime_chunk_samples(trak, chunk);
 218         chunk_bytes = ima4_samples_to_bytes(chunk_samples, file->atracks[track].channels);
 219
 220 /* Get the buffer to read into. */
 221         if(codec->work_buffer && codec->work_size < chunk_samples)
 222         {
 223                 free(codec->work_buffer);
 224                 codec->work_buffer = 0;
 225         }
 226
 227         if(!codec->work_buffer)
 228         {
 229                 codec->work_size = chunk_samples;
 230                 codec->work_buffer = malloc(sizeof(int16_t) * codec->work_size);
 231         }
 232
 233         if(codec->read_buffer && codec->read_size < chunk_bytes)
 234         {
 235                 free(codec->read_buffer);
 236                 codec->read_buffer = 0;
 237         }
 238
 239         if(!codec->read_buffer)
 240         {
 241                 codec->read_size = chunk_bytes;
 242                 codec->read_buffer = malloc(codec->read_size);
 243         }
 244
 245 /* codec->work_size now holds the number of samples in the last chunk */
 246 /* codec->read_size now holds number of bytes in the last read buffer */
 247
 248 /* Read the entire chunk regardless of where the desired sample range starts. */
 249         result = quicktime_read_chunk(file, codec->read_buffer, track, chunk, 0, chunk_bytes);
 250
 251 /* Now decode the chunk, one block at a time, until the total samples in the chunk */
 252 /* is reached. */
 253
 254         if(!result)
 255         {
 256                 block_ptr = codec->read_buffer;
 257                 for(i = 0; i < chunk_samples; i += SAMPLES_PER_BLOCK)
 258                 {
 259                         for(j = 0; j < file->atracks[track].channels; j++)
 260                         {
 261                                 if(j == channel)
 262                                         ima4_decode_block(&(file->atracks[track]), &(codec->work_buffer[i]), block_ptr);
 263
 264                                 block_ptr += BLOCK_SIZE;
 265                         }
 266                 }
 267         }
 268         codec->buffer_channel = channel;
 269         codec->chunk = chunk;
 270
 271         return result;
 272 }
 273
 274
 275 /* =================================== public for ima4 */
 276
 277 static int delete_codec(quicktime_audio_map_t *atrack)
 278 {
 279         quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)atrack->codec)->priv;
 280
 281         if(codec->work_buffer) free(codec->work_buffer);
 282         if(codec->read_buffer) free(codec->read_buffer);
 283         if(codec->last_samples) free(codec->last_samples);
 284         if(codec->last_indexes) free(codec->last_indexes);
 285         codec->last_samples = 0;
 286         codec->last_indexes = 0;
 287         codec->read_buffer = 0;
 288         codec->work_buffer = 0;
 289         codec->chunk = 0;
 290         codec->buffer_channel = 0; /* Channel of work buffer */
 291         codec->work_size = 0;          /* Size of work buffer */
 292         codec->read_size = 0;
 293         free(codec);
 294         return 0;
 295 }
 296
 297 static int decode(quicktime_t *file,
 298                                         int16_t *output_i,
 299                                         float *output_f,
 300                                         long samples,
 301                                         int track,
 302                                         int channel)
 303 {
 304         int result = 0;
 305         int64_t chunk, chunk_sample, chunk_bytes, chunk_samples;
 306         int64_t i, chunk_start, chunk_end;
 307         quicktime_trak_t *trak = file->atracks[track].track;
 308         quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)file->atracks[track].codec)->priv;
 309
 310 /* Get the first chunk with this routine and then increase the chunk number. */
 311         quicktime_chunk_of_sample(&chunk_sample, &chunk, trak, file->atracks[track].current_position);
 312
 313 /* Read chunks and extract ranges of samples until the output is full. */
 314         for(i = 0; i < samples && !result; )
 315         {
 316 /* Get chunk we're on. */
 317                 chunk_samples = quicktime_chunk_samples(trak, chunk);
 318
 319                 if(!codec->work_buffer ||
 320                         codec->chunk != chunk ||
 321                         codec->buffer_channel != channel)
 322                 {
 323 /* read a new chunk if necessary */
 324                         result = ima4_decode_chunk(file, track, chunk, channel);
 325                 }
 326
 327 /* Get boundaries from the chunk */
 328                 chunk_start = 0;
 329                 if(chunk_sample < file->atracks[track].current_position)
 330                         chunk_start = file->atracks[track].current_position - chunk_sample;
 331
 332                 chunk_end = chunk_samples;
 333                 if(chunk_sample + chunk_end > file->atracks[track].current_position + samples)
 334                         chunk_end = file->atracks[track].current_position + samples - chunk_sample;
 335
 336 /* Read from the chunk */
 337                 if(output_i)
 338                 {
 339 /*printf("decode_ima4 1 chunk %ld %ld-%ld output %ld\n", chunk, chunk_start + chunk_sample, chunk_end + chunk_sample, i); */
 340                         while(chunk_start < chunk_end)
 341                         {
 342                                 output_i[i++] = codec->work_buffer[chunk_start++];
 343                         }
 344 /*printf("decode_ima4 2\n"); */
 345                 }
 346                 else
 347                 if(output_f)
 348                 {
 349                         while(chunk_start < chunk_end)
 350                         {
 351                                 output_f[i++] = (float)codec->work_buffer[chunk_start++] / 32767;
 352                         }
 353                 }
 354
 355                 chunk++;
 356                 chunk_sample += chunk_samples;
 357         }
 358
 359         return result;
 360 }
 361
 362 static int encode(quicktime_t *file,
 363                                                 int16_t **input_i,
 364                                                 float **input_f,
 365                                                 int track,
 366                                                 long samples)
 367 {
 368         int result = 0;
 369         int64_t i, j, step;
 370         int64_t chunk_bytes;
 371         int64_t overflow_start;
 372         int64_t offset;
 373         int64_t chunk_samples; /* Samples in the current chunk to be written */
 374         quicktime_audio_map_t *track_map = &(file->atracks[track]);
 375         quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)track_map->codec)->priv;
 376         quicktime_trak_t *trak = track_map->track;
 377         int16_t *input_ptr;
 378         unsigned char *output_ptr;
 379         quicktime_atom_t chunk_atom;
 380
 381 /* Get buffer sizes */
 382         if(codec->work_buffer && codec->work_size < (samples + codec->work_overflow + 1) * track_map->channels)
 383         {
 384 /* Create new buffer */
 385                 int64_t new_size = (samples + codec->work_overflow + 1) * track_map->channels;
 386                 int16_t *new_buffer = malloc(sizeof(int16_t) * new_size);
 387
 388 /* Copy overflow */
 389                 for(i = 0; i < codec->work_overflow * track_map->channels; i++)
 390                         new_buffer[i] = codec->work_buffer[i];
 391
 392 /* Swap pointers. */
 393                 free(codec->work_buffer);
 394                 codec->work_buffer = new_buffer;
 395                 codec->work_size = new_size;
 396         }
 397         else
 398         if(!codec->work_buffer)
 399         {
 400 /* No buffer in the first place. */
 401                 codec->work_size = (samples + codec->work_overflow) * track_map->channels;
 402 /* Make the allocation enough for at least the flush routine. */
 403                 if(codec->work_size < SAMPLES_PER_BLOCK * track_map->channels)
 404                         codec->work_size = SAMPLES_PER_BLOCK * track_map->channels;
 405                 codec->work_buffer = malloc(sizeof(int16_t) * codec->work_size);
 406         }
 407
 408 /* Get output size */
 409         chunk_bytes = ima4_samples_to_bytes(samples + codec->work_overflow, track_map->channels);
 410         if(codec->read_buffer && codec->read_size < chunk_bytes)
 411         {
 412                 free(codec->read_buffer);
 413                 codec->read_buffer = 0;
 414         }
 415
 416         if(!codec->read_buffer)
 417         {
 418                 codec->read_buffer = malloc(chunk_bytes);
 419                 codec->read_size = chunk_bytes;
 420         }
 421
 422         if(!codec->last_samples)
 423         {
 424                 codec->last_samples = malloc(sizeof(int) * track_map->channels);
 425                 for(i = 0; i < track_map->channels; i++)
 426                 {
 427                         codec->last_samples[i] = 0;
 428                 }
 429         }
 430
 431         if(!codec->last_indexes)
 432         {
 433                 codec->last_indexes = malloc(sizeof(int) * track_map->channels);
 434                 for(i = 0; i < track_map->channels; i++)
 435                 {
 436                         codec->last_indexes[i] = 0;
 437                 }
 438         }
 439
 440 /* Arm the input buffer after the last overflow */
 441         step = track_map->channels;
 442         for(j = 0; j < track_map->channels; j++)
 443         {
 444                 input_ptr = codec->work_buffer + codec->work_overflow * track_map->channels + j;
 445
 446                 if(input_i)
 447                 {
 448                         for(i = 0; i < samples; i++)
 449                         {
 450                                 *input_ptr = input_i[j][i];
 451                                 input_ptr += step;
 452                         }
 453                 }
 454                 else
 455                 if(input_f)
 456                 {
 457                         for(i = 0; i < samples; i++)
 458                         {
 459                                 *input_ptr = (int16_t)(input_f[j][i] * 32767);
 460                                 input_ptr += step;
 461                         }
 462                 }
 463         }
 464
 465 /* Encode from the input buffer to the read_buffer up to a multiple of  */
 466 /* blocks. */
 467         input_ptr = codec->work_buffer;
 468         output_ptr = codec->read_buffer;
 469
 470         for(i = 0;
 471                 i + SAMPLES_PER_BLOCK <= samples + codec->work_overflow;
 472                 i += SAMPLES_PER_BLOCK)
 473         {
 474                 for(j = 0; j < track_map->channels; j++)
 475                 {
 476                         ima4_encode_block(track_map, output_ptr, input_ptr + j, track_map->channels, j);
 477
 478                         output_ptr += BLOCK_SIZE;
 479                 }
 480                 input_ptr += SAMPLES_PER_BLOCK * track_map->channels;
 481         }
 482
 483 /* Write to disk */
 484         chunk_samples = (int64_t)((samples + codec->work_overflow) / SAMPLES_PER_BLOCK) * SAMPLES_PER_BLOCK;
 485
 486 /*printf("quicktime_encode_ima4 1 %ld\n", chunk_samples); */
 487 /* The block division may result in 0 samples getting encoded. */
 488 /* Don't write 0 samples. */
 489         if(chunk_samples)
 490         {
 491                 quicktime_write_chunk_header(file, trak, &chunk_atom);
 492                 result = quicktime_write_data(file, codec->read_buffer, chunk_bytes);
 493                 quicktime_write_chunk_footer(file,
 494                         trak,
 495                         track_map->current_chunk,
 496                         &chunk_atom,
 497                         chunk_samples);
 498
 499                 if(result)
 500                         result = 0;
 501                 else
 502                         result = 1; /* defeat fwrite's return */
 503
 504                 track_map->current_chunk++;
 505         }
 506
 507 /* Move the last overflow to the front */
 508         overflow_start = i;
 509         input_ptr = codec->work_buffer;
 510         for(i = overflow_start * track_map->channels ;
 511                 i < (samples + codec->work_overflow) * track_map->channels;
 512                 i++)
 513         {
 514                 *input_ptr++ = codec->work_buffer[i];
 515         }
 516         codec->work_overflow = samples + codec->work_overflow - overflow_start;
 517
 518         return result;
 519 }
 520
 521 void flush(quicktime_t *file, int track)
 522 {
 523         quicktime_audio_map_t *track_map = &(file->atracks[track]);
 524         quicktime_ima4_codec_t *codec = ((quicktime_codec_t*)track_map->codec)->priv;
 525         int result = 0;
 526         int i;
 527
 528 /*printf("quicktime_flush_ima4 %ld\n", codec->work_overflow); */
 529         if(codec->work_overflow)
 530         {
 531 /* Zero out enough to get a block */
 532                 i = codec->work_overflow * track_map->channels;
 533                 while(i < SAMPLES_PER_BLOCK * track_map->channels)
 534                 {
 535                         codec->work_buffer[i++] = 0;
 536                 }
 537                 codec->work_overflow = i / track_map->channels + 1;
 538 /* Write the work_overflow only. */
 539                 result = encode(file, 0, 0, track, 0);
 540         }
 541 }
 542
 543 void quicktime_init_codec_ima4(quicktime_audio_map_t *atrack)
 544 {
 545         quicktime_codec_t *codec_base = (quicktime_codec_t*)atrack->codec;
 546         quicktime_ima4_codec_t *codec;
 547
 548 /* Init public items */
 549         codec_base->priv = calloc(1, sizeof(quicktime_ima4_codec_t));
 550         codec_base->delete_acodec = delete_codec;
 551         codec_base->decode_video = 0;
 552         codec_base->encode_video = 0;
 553         codec_base->decode_audio = decode;
 554         codec_base->encode_audio = encode;
 555         codec_base->flush = flush;
 556         codec_base->fourcc = QUICKTIME_IMA4;
 557         codec_base->title = "IMA 4";
 558         codec_base->desc = "IMA 4";
 559         codec_base->wav_id = 0x11;
 560
 561 /* Init private items */
 562         codec = codec_base->priv;
 563 }