apps/codecs/flac.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2005 Dave Chapman
  11  *
  12  * All files in this archive are subject to the GNU General Public License.
  13  * See the file COPYING in the source tree root for full license agreement.
  14  *
  15  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  16  * KIND, either express or implied.
  17  *
  18  ****************************************************************************/
  19
  20 #include "codeclib.h"
  21 #include <codecs/libffmpegFLAC/decoder.h>
  22
  23 CODEC_HEADER
  24
  25 /* The output buffers containing the decoded samples (channels 0 and 1) */
  26 int32_t decoded0[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_DECODED0;
  27 int32_t decoded1[MAX_BLOCKSIZE] IBSS_ATTR;
  28
  29 #define MAX_SUPPORTED_SEEKTABLE_SIZE 5000
  30
  31 /* Notes about seeking:
  32
  33    The full seek table consists of:
  34       uint64_t sample (only 36 bits are used)
  35       uint64_t offset
  36       uint32_t blocksize
  37
  38    We also limit the sample and offset values to 32-bits - Rockbox doesn't
  39    support files bigger than 2GB on FAT32 filesystems.
  40
  41    The reference FLAC encoder produces a seek table with points every
  42    10 seconds, but this can be overridden by the user when encoding a file.
  43
  44    With the default settings, a typical 4 minute track will contain
  45    24 seek points.
  46
  47    Taking the extreme case of a Rockbox supported file to be a 2GB (compressed)
  48    16-bit/44.1KHz mono stream with a likely uncompressed size of 4GB:
  49       Total duration is: 48694 seconds (about 810 minutes - 13.5 hours)
  50       Total number of seek points: 4869
  51
  52    Therefore we limit the number of seek points to 5000.  This is a
  53    very extreme case, and requires 5000*8=40000 bytes of storage.
  54
  55    If we come across a FLAC file with more than this number of seekpoints, we
  56    just use the first 5000.
  57
  58 */
  59
  60 struct FLACseekpoints {
  61     uint32_t sample;
  62     uint32_t offset;
  63     uint16_t blocksize;
  64 };
  65
  66 struct FLACseekpoints seekpoints[MAX_SUPPORTED_SEEKTABLE_SIZE];
  67 int nseekpoints;
  68
  69 static int8_t *bit_buffer;
  70 static size_t buff_size;
  71
  72 static bool flac_init(FLACContext* fc, int first_frame_offset)
  73 {
  74     unsigned char buf[255];
  75     bool found_streaminfo=false;
  76     uint32_t seekpoint_hi,seekpoint_lo;
  77     uint32_t offset_hi,offset_lo;
  78     uint16_t blocksize;
  79     int endofmetadata=0;
  80     uint32_t blocklength;
  81
  82     ci->memset(fc,0,sizeof(FLACContext));
  83     nseekpoints=0;
  84
  85     fc->sample_skip = 0;
  86
  87     /* Skip any foreign tags at start of file */
  88     ci->seek_buffer(first_frame_offset);
  89
  90     fc->metadatalength = first_frame_offset;
  91
  92     if (ci->read_filebuf(buf, 4) < 4)
  93     {
  94         return false;
  95     }
  96
  97     if (ci->memcmp(buf,"fLaC",4) != 0)
  98     {
  99         return false;
 100     }
 101     fc->metadatalength += 4;
 102
 103     while (!endofmetadata) {
 104         if (ci->read_filebuf(buf, 4) < 4)
 105         {
 106             return false;
 107         }
 108
 109         endofmetadata=(buf[0]&0x80);
 110         blocklength = (buf[1] << 16) | (buf[2] << 8) | buf[3];
 111         fc->metadatalength+=blocklength+4;
 112
 113         if ((buf[0] & 0x7f) == 0)       /* 0 is the STREAMINFO block */
 114         {
 115             if (ci->read_filebuf(buf, blocklength) < blocklength) return false;
 116
 117             fc->filesize = ci->filesize;
 118             fc->min_blocksize = (buf[0] << 8) | buf[1];
 119             fc->max_blocksize = (buf[2] << 8) | buf[3];
 120             fc->min_framesize = (buf[4] << 16) | (buf[5] << 8) | buf[6];
 121             fc->max_framesize = (buf[7] << 16) | (buf[8] << 8) | buf[9];
 122             fc->samplerate = (buf[10] << 12) | (buf[11] << 4)
 123                              | ((buf[12] & 0xf0) >> 4);
 124             fc->channels = ((buf[12]&0x0e)>>1) + 1;
 125             fc->bps = (((buf[12]&0x01) << 4) | ((buf[13]&0xf0)>>4) ) + 1;
 126
 127             /* totalsamples is a 36-bit field, but we assume <= 32 bits are
 128                used */
 129             fc->totalsamples = (buf[14] << 24) | (buf[15] << 16)
 130                                | (buf[16] << 8) | buf[17];
 131
 132             /* Calculate track length (in ms) and estimate the bitrate
 133                (in kbit/s) */
 134             fc->length = (fc->totalsamples / fc->samplerate) * 1000;
 135
 136             found_streaminfo=true;
 137         } else if ((buf[0] & 0x7f) == 3) { /* 3 is the SEEKTABLE block */
 138             while ((nseekpoints < MAX_SUPPORTED_SEEKTABLE_SIZE) &&
 139                    (blocklength >= 18)) {
 140                 if (ci->read_filebuf(buf,18) < 18) return false;
 141                 blocklength-=18;
 142
 143                 seekpoint_hi=(buf[0] << 24) | (buf[1] << 16) |
 144                              (buf[2] << 8) | buf[3];
 145                 seekpoint_lo=(buf[4] << 24) | (buf[5] << 16) |
 146                              (buf[6] << 8) | buf[7];
 147                 offset_hi=(buf[8] << 24) | (buf[9] << 16) |
 148                              (buf[10] << 8) | buf[11];
 149                 offset_lo=(buf[12] << 24) | (buf[13] << 16) |
 150                              (buf[14] << 8) | buf[15];
 151
 152                 blocksize=(buf[16] << 8) | buf[17];
 153
 154                 /* Only store seekpoints where the high 32 bits are zero */
 155                 if ((seekpoint_hi == 0) && (seekpoint_lo != 0xffffffff) &&
 156                     (offset_hi == 0)) {
 157                         seekpoints[nseekpoints].sample=seekpoint_lo;
 158                         seekpoints[nseekpoints].offset=offset_lo;
 159                         seekpoints[nseekpoints].blocksize=blocksize;
 160                         nseekpoints++;
 161                 }
 162             }
 163             /* Skip any unread seekpoints */
 164             if (blocklength > 0)
 165                 ci->advance_buffer(blocklength);
 166         } else {
 167           /* Skip to next metadata block */
 168           ci->advance_buffer(blocklength);
 169         }
 170     }
 171
 172    if (found_streaminfo) {
 173        fc->bitrate = ((fc->filesize-fc->metadatalength) * 8) / fc->length;
 174        return true;
 175    } else {
 176        return false;
 177    }
 178 }
 179
 180 /* Synchronize to next frame in stream - adapted from libFLAC 1.1.3b2 */
 181 bool frame_sync(FLACContext* fc) {
 182     unsigned int x = 0;
 183     bool cached = false;
 184
 185     /* Make sure we're byte aligned. */
 186     align_get_bits(&fc->gb);
 187
 188     while(1) {
 189         if(fc->gb.size_in_bits - get_bits_count(&fc->gb) < 8) {
 190             /* Error, end of bitstream, a valid stream should never reach here
 191              * since the buffer should contain at least one frame header.
 192              */
 193             return false;
 194         }
 195
 196         if(cached)
 197             cached = false;
 198         else
 199             x = get_bits(&fc->gb, 8);
 200
 201         if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 202             x = get_bits(&fc->gb, 8);
 203             /* We have to check if we just read two 0xff's in a row; the second
 204              * may actually be the beginning of the sync code.
 205              */
 206             if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 207                 cached = true;
 208             }
 209             else if(x >> 2 == 0x3e) { /* MAGIC NUMBER for last 6 sync bits. */
 210                 /* Succesfully synced. */
 211                 break;
 212             }
 213         }
 214     }
 215
 216     /* Advance and init bit buffer to the new frame. */
 217     ci->advance_buffer((get_bits_count(&fc->gb)-16)>>3); /* consumed bytes */
 218     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 219     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 220
 221     /* Decode the frame to verify the frame crc and
 222      * fill fc with its metadata.
 223      */
 224     if(flac_decode_frame(fc, decoded0, decoded1,
 225        bit_buffer, buff_size, ci->yield) < 0) {
 226         return false;
 227     }
 228
 229     return true;
 230 }
 231
 232 /* Seek to sample - adapted from libFLAC 1.1.3b2+ */
 233 bool flac_seek(FLACContext* fc, uint32_t target_sample) {
 234     off_t orig_pos = ci->curpos;
 235     off_t pos = -1;
 236     unsigned long lower_bound, upper_bound;
 237     unsigned long lower_bound_sample, upper_bound_sample;
 238     int i;
 239     unsigned approx_bytes_per_frame;
 240     uint32_t this_frame_sample = fc->samplenumber;
 241     unsigned this_block_size = fc->blocksize;
 242     bool needs_seek = true, first_seek = true;
 243
 244     /* We are just guessing here. */
 245     if(fc->max_framesize > 0)
 246         approx_bytes_per_frame = (fc->max_framesize + fc->min_framesize)/2 + 1;
 247     /* Check if it's a known fixed-blocksize stream. */
 248     else if(fc->min_blocksize == fc->max_blocksize && fc->min_blocksize > 0)
 249         approx_bytes_per_frame = fc->min_blocksize*fc->channels*fc->bps/8 + 64;
 250     else
 251         approx_bytes_per_frame = 4608 * fc->channels * fc->bps/8 + 64;
 252
 253     /* Set an upper and lower bound on where in the stream we will search. */
 254     lower_bound = fc->metadatalength;
 255     lower_bound_sample = 0;
 256     upper_bound = fc->filesize;
 257     upper_bound_sample = fc->totalsamples>0 ? fc->totalsamples : target_sample;
 258
 259     /* Refine the bounds if we have a seektable with suitable points. */
 260     if(nseekpoints > 0) {
 261         /* Find the closest seek point <= target_sample, if it exists. */
 262         for(i = nseekpoints-1; i >= 0; i--) {
 263             if(seekpoints[i].sample <= target_sample)
 264                 break;
 265         }
 266         if(i >= 0) { /* i.e. we found a suitable seek point... */
 267             lower_bound = fc->metadatalength + seekpoints[i].offset;
 268             lower_bound_sample = seekpoints[i].sample;
 269         }
 270
 271         /* Find the closest seek point > target_sample, if it exists. */
 272         for(i = 0; i < nseekpoints; i++) {
 273             if(seekpoints[i].sample > target_sample)
 274                 break;
 275         }
 276         if(i < nseekpoints) { /* i.e. we found a suitable seek point... */
 277             upper_bound = fc->metadatalength + seekpoints[i].offset;
 278             upper_bound_sample = seekpoints[i].sample;
 279         }
 280     }
 281
 282     while(1) {
 283         /* Check if bounds are still ok. */
 284         if(lower_bound_sample >= upper_bound_sample ||
 285            lower_bound > upper_bound) {
 286             return false;
 287         }
 288
 289         /* Calculate new seek position */
 290         if(needs_seek) {
 291             pos = (off_t)(lower_bound +
 292               (((target_sample - lower_bound_sample) *
 293               (int64_t)(upper_bound - lower_bound)) /
 294               (upper_bound_sample - lower_bound_sample)) -
 295               approx_bytes_per_frame);
 296
 297             if(pos >= (off_t)upper_bound)
 298                 pos = (off_t)upper_bound-1;
 299             if(pos < (off_t)lower_bound)
 300                 pos = (off_t)lower_bound;
 301         }
 302
 303         if(!ci->seek_buffer(pos))
 304             return false;
 305
 306         bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 307         init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 308
 309         /* Now we need to get a frame.  It is possible for our seek
 310          * to land in the middle of audio data that looks exactly like
 311          * a frame header from a future version of an encoder.  When
 312          * that happens, frame_sync() will return false.
 313          * But there is a remote possibility that it is properly
 314          * synced at such a "future-codec frame", so to make sure,
 315          * we wait to see several "unparseable" errors in a row before
 316          * bailing out.
 317          */
 318         {
 319             unsigned unparseable_count;
 320             bool got_a_frame = false;
 321             for(unparseable_count = 0; !got_a_frame
 322                 && unparseable_count < 10; unparseable_count++) {
 323                 if(frame_sync(fc))
 324                     got_a_frame = true;
 325             }
 326             if(!got_a_frame) {
 327                 ci->seek_buffer(orig_pos);
 328                 return false;
 329             }
 330         }
 331
 332         this_frame_sample = fc->samplenumber;
 333         this_block_size = fc->blocksize;
 334
 335         if(target_sample >= this_frame_sample
 336            && target_sample < this_frame_sample+this_block_size) {
 337             /* Found the frame containing the target sample. */
 338             fc->sample_skip = target_sample - this_frame_sample;
 339             break;
 340         }
 341
 342         if(this_frame_sample + this_block_size >= upper_bound_sample &&
 343            !first_seek) {
 344             if(pos == (off_t)lower_bound || !needs_seek) {
 345                 ci->seek_buffer(orig_pos);
 346                 return false;
 347             }
 348             /* Our last move backwards wasn't big enough, try again. */
 349             approx_bytes_per_frame *= 2;
 350             continue;
 351         }
 352         /* Allow one seek over upper bound,
 353          * required for streams with unknown total samples.
 354          */
 355         first_seek = false;
 356
 357         /* Make sure we are not seeking in a corrupted stream */
 358         if(this_frame_sample < lower_bound_sample) {
 359             ci->seek_buffer(orig_pos);
 360             return false;
 361         }
 362
 363         approx_bytes_per_frame = this_block_size*fc->channels*fc->bps/8 + 64;
 364
 365         /* We need to narrow the search. */
 366         if(target_sample < this_frame_sample) {
 367             upper_bound_sample = this_frame_sample;
 368             upper_bound = ci->curpos;
 369         }
 370         else { /* Target is beyond this frame. */
 371             /* We are close, continue in decoding next frames. */
 372             if(target_sample < this_frame_sample + 4*this_block_size) {
 373                 pos = ci->curpos + fc->framesize;
 374                 needs_seek = false;
 375             }
 376
 377             lower_bound_sample = this_frame_sample + this_block_size;
 378             lower_bound = ci->curpos + fc->framesize;
 379         }
 380     }
 381
 382     return true;
 383 }
 384
 385 /* Seek to file offset */
 386 bool flac_seek_offset(FLACContext* fc, uint32_t offset) {
 387     unsigned unparseable_count;
 388     bool got_a_frame = false;
 389
 390     if(!ci->seek_buffer(offset))
 391         return false;
 392
 393     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE);
 394     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 395
 396     for(unparseable_count = 0; !got_a_frame
 397         && unparseable_count < 10; unparseable_count++) {
 398         if(frame_sync(fc))
 399             got_a_frame = true;
 400     }
 401
 402     if(!got_a_frame) {
 403         ci->seek_buffer(fc->metadatalength);
 404         return false;
 405     }
 406
 407     return true;
 408 }
 409
 410 /* this is the codec entry point */
 411 enum codec_status codec_main(void)
 412 {
 413     int8_t *buf;
 414     FLACContext fc;
 415     uint32_t samplesdone = 0;
 416     uint32_t elapsedtime;
 417     size_t bytesleft;
 418     int consumed;
 419     int res;
 420     int frame;
 421     int retval;
 422
 423     /* Generic codec initialisation */
 424     ci->configure(CODEC_SET_FILEBUF_WATERMARK, 1024*512);
 425
 426     ci->configure(DSP_SET_SAMPLE_DEPTH, FLAC_OUTPUT_DEPTH-1);
 427
 428     next_track:
 429
 430     /* Need to save offset for later use (cleared indirectly by flac_init) */
 431     samplesdone=ci->id3->offset;
 432
 433     if (codec_init()) {
 434         LOGF("FLAC: Error initialising codec\n");
 435         retval = CODEC_ERROR;
 436         goto exit;
 437     }
 438
 439     while (!*ci->taginfo_ready && !ci->stop_codec)
 440         ci->sleep(1);
 441
 442     if (!flac_init(&fc,ci->id3->first_frame_offset)) {
 443         LOGF("FLAC: Error initialising codec\n");
 444         retval = CODEC_ERROR;
 445         goto done;
 446     }
 447
 448     ci->configure(DSP_SWITCH_FREQUENCY, ci->id3->frequency);
 449     ci->configure(DSP_SET_STEREO_MODE, fc.channels == 1 ?
 450                   STEREO_MONO : STEREO_NONINTERLEAVED);
 451     codec_set_replaygain(ci->id3);
 452
 453     if (samplesdone) {
 454         flac_seek_offset(&fc, samplesdone);
 455         samplesdone=0;
 456     }
 457
 458     /* The main decoding loop */
 459     frame=0;
 460     buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 461     while (bytesleft) {
 462         ci->yield();
 463         if (ci->stop_codec || ci->new_track) {
 464             break;
 465         }
 466
 467         /* Deal with any pending seek requests */
 468         if (ci->seek_time) {
 469             if (flac_seek(&fc,(uint32_t)(((uint64_t)(ci->seek_time-1)
 470                 *ci->id3->frequency)/1000))) {
 471                 /* Refill the input buffer */
 472                 buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 473             }
 474             ci->seek_complete();
 475         }
 476
 477         if((res=flac_decode_frame(&fc,decoded0,decoded1,buf,
 478                              bytesleft,ci->yield)) < 0) {
 479              LOGF("FLAC: Frame %d, error %d\n",frame,res);
 480              retval = CODEC_ERROR;
 481              goto done;
 482         }
 483         consumed=fc.gb.index/8;
 484         frame++;
 485
 486         ci->yield();
 487         ci->pcmbuf_insert(&decoded0[fc.sample_skip], &decoded1[fc.sample_skip],
 488                           fc.blocksize - fc.sample_skip);
 489
 490         fc.sample_skip = 0;
 491
 492         /* Update the elapsed-time indicator */
 493         samplesdone=fc.samplenumber+fc.blocksize;
 494         elapsedtime=(samplesdone*10)/(ci->id3->frequency/100);
 495         ci->set_elapsed(elapsedtime);
 496
 497         ci->advance_buffer(consumed);
 498
 499         buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 500     }
 501     retval = CODEC_OK;
 502
 503 done:
 504     LOGF("FLAC: Decoded %ld samples\n",samplesdone);
 505
 506     if (ci->request_next_track())
 507         goto next_track;
 508
 509 exit:
 510     return retval;
 511 }