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  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #include "codeclib.h"
  23 #include <codecs/libffmpegFLAC/decoder.h>
  24
  25 CODEC_HEADER
  26
  27 /* The output buffers containing the decoded samples (channels 0 and 1) */
  28 int32_t decoded0[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_DECODED0;
  29 int32_t decoded1[MAX_BLOCKSIZE] IBSS_ATTR;
  30
  31 #define MAX_SUPPORTED_SEEKTABLE_SIZE 5000
  32
  33 /* Notes about seeking:
  34
  35    The full seek table consists of:
  36       uint64_t sample (only 36 bits are used)
  37       uint64_t offset
  38       uint32_t blocksize
  39
  40    We also limit the sample and offset values to 32-bits - Rockbox doesn't
  41    support files bigger than 2GB on FAT32 filesystems.
  42
  43    The reference FLAC encoder produces a seek table with points every
  44    10 seconds, but this can be overridden by the user when encoding a file.
  45
  46    With the default settings, a typical 4 minute track will contain
  47    24 seek points.
  48
  49    Taking the extreme case of a Rockbox supported file to be a 2GB (compressed)
  50    16-bit/44.1KHz mono stream with a likely uncompressed size of 4GB:
  51       Total duration is: 48694 seconds (about 810 minutes - 13.5 hours)
  52       Total number of seek points: 4869
  53
  54    Therefore we limit the number of seek points to 5000.  This is a
  55    very extreme case, and requires 5000*8=40000 bytes of storage.
  56
  57    If we come across a FLAC file with more than this number of seekpoints, we
  58    just use the first 5000.
  59
  60 */
  61
  62 struct FLACseekpoints {
  63     uint32_t sample;
  64     uint32_t offset;
  65     uint16_t blocksize;
  66 };
  67
  68 struct FLACseekpoints seekpoints[MAX_SUPPORTED_SEEKTABLE_SIZE];
  69 int nseekpoints;
  70
  71 static int8_t *bit_buffer;
  72 static size_t buff_size;
  73
  74 static bool flac_init(FLACContext* fc, int first_frame_offset)
  75 {
  76     unsigned char buf[255];
  77     bool found_streaminfo=false;
  78     uint32_t seekpoint_hi,seekpoint_lo;
  79     uint32_t offset_hi,offset_lo;
  80     uint16_t blocksize;
  81     int endofmetadata=0;
  82     uint32_t blocklength;
  83
  84     ci->memset(fc,0,sizeof(FLACContext));
  85     nseekpoints=0;
  86
  87     fc->sample_skip = 0;
  88
  89     /* Skip any foreign tags at start of file */
  90     ci->seek_buffer(first_frame_offset);
  91
  92     fc->metadatalength = first_frame_offset;
  93
  94     if (ci->read_filebuf(buf, 4) < 4)
  95     {
  96         return false;
  97     }
  98
  99     if (ci->memcmp(buf,"fLaC",4) != 0)
 100     {
 101         return false;
 102     }
 103     fc->metadatalength += 4;
 104
 105     while (!endofmetadata) {
 106         if (ci->read_filebuf(buf, 4) < 4)
 107         {
 108             return false;
 109         }
 110
 111         endofmetadata=(buf[0]&0x80);
 112         blocklength = (buf[1] << 16) | (buf[2] << 8) | buf[3];
 113         fc->metadatalength+=blocklength+4;
 114
 115         if ((buf[0] & 0x7f) == 0)       /* 0 is the STREAMINFO block */
 116         {
 117             if (ci->read_filebuf(buf, blocklength) < blocklength) return false;
 118
 119             fc->filesize = ci->filesize;
 120             fc->min_blocksize = (buf[0] << 8) | buf[1];
 121             fc->max_blocksize = (buf[2] << 8) | buf[3];
 122             fc->min_framesize = (buf[4] << 16) | (buf[5] << 8) | buf[6];
 123             fc->max_framesize = (buf[7] << 16) | (buf[8] << 8) | buf[9];
 124             fc->samplerate = (buf[10] << 12) | (buf[11] << 4)
 125                              | ((buf[12] & 0xf0) >> 4);
 126             fc->channels = ((buf[12]&0x0e)>>1) + 1;
 127             fc->bps = (((buf[12]&0x01) << 4) | ((buf[13]&0xf0)>>4) ) + 1;
 128
 129             /* totalsamples is a 36-bit field, but we assume <= 32 bits are
 130                used */
 131             fc->totalsamples = (buf[14] << 24) | (buf[15] << 16)
 132                                | (buf[16] << 8) | buf[17];
 133
 134             /* Calculate track length (in ms) and estimate the bitrate
 135                (in kbit/s) */
 136             fc->length = (fc->totalsamples / fc->samplerate) * 1000;
 137
 138             found_streaminfo=true;
 139         } else if ((buf[0] & 0x7f) == 3) { /* 3 is the SEEKTABLE block */
 140             while ((nseekpoints < MAX_SUPPORTED_SEEKTABLE_SIZE) &&
 141                    (blocklength >= 18)) {
 142                 if (ci->read_filebuf(buf,18) < 18) return false;
 143                 blocklength-=18;
 144
 145                 seekpoint_hi=(buf[0] << 24) | (buf[1] << 16) |
 146                              (buf[2] << 8) | buf[3];
 147                 seekpoint_lo=(buf[4] << 24) | (buf[5] << 16) |
 148                              (buf[6] << 8) | buf[7];
 149                 offset_hi=(buf[8] << 24) | (buf[9] << 16) |
 150                              (buf[10] << 8) | buf[11];
 151                 offset_lo=(buf[12] << 24) | (buf[13] << 16) |
 152                              (buf[14] << 8) | buf[15];
 153
 154                 blocksize=(buf[16] << 8) | buf[17];
 155
 156                 /* Only store seekpoints where the high 32 bits are zero */
 157                 if ((seekpoint_hi == 0) && (seekpoint_lo != 0xffffffff) &&
 158                     (offset_hi == 0)) {
 159                         seekpoints[nseekpoints].sample=seekpoint_lo;
 160                         seekpoints[nseekpoints].offset=offset_lo;
 161                         seekpoints[nseekpoints].blocksize=blocksize;
 162                         nseekpoints++;
 163                 }
 164             }
 165             /* Skip any unread seekpoints */
 166             if (blocklength > 0)
 167                 ci->advance_buffer(blocklength);
 168         } else {
 169           /* Skip to next metadata block */
 170           ci->advance_buffer(blocklength);
 171         }
 172     }
 173
 174    if (found_streaminfo) {
 175        fc->bitrate = ((fc->filesize-fc->metadatalength) * 8) / fc->length;
 176        return true;
 177    } else {
 178        return false;
 179    }
 180 }
 181
 182 /* Synchronize to next frame in stream - adapted from libFLAC 1.1.3b2 */
 183 bool frame_sync(FLACContext* fc) {
 184     unsigned int x = 0;
 185     bool cached = false;
 186
 187     /* Make sure we're byte aligned. */
 188     align_get_bits(&fc->gb);
 189
 190     while(1) {
 191         if(fc->gb.size_in_bits - get_bits_count(&fc->gb) < 8) {
 192             /* Error, end of bitstream, a valid stream should never reach here
 193              * since the buffer should contain at least one frame header.
 194              */
 195             return false;
 196         }
 197
 198         if(cached)
 199             cached = false;
 200         else
 201             x = get_bits(&fc->gb, 8);
 202
 203         if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 204             x = get_bits(&fc->gb, 8);
 205             /* We have to check if we just read two 0xff's in a row; the second
 206              * may actually be the beginning of the sync code.
 207              */
 208             if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 209                 cached = true;
 210             }
 211             else if(x >> 2 == 0x3e) { /* MAGIC NUMBER for last 6 sync bits. */
 212                 /* Succesfully synced. */
 213                 break;
 214             }
 215         }
 216     }
 217
 218     /* Advance and init bit buffer to the new frame. */
 219     ci->advance_buffer((get_bits_count(&fc->gb)-16)>>3); /* consumed bytes */
 220     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 221     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 222
 223     /* Decode the frame to verify the frame crc and
 224      * fill fc with its metadata.
 225      */
 226     if(flac_decode_frame(fc, decoded0, decoded1,
 227        bit_buffer, buff_size, ci->yield) < 0) {
 228         return false;
 229     }
 230
 231     return true;
 232 }
 233
 234 /* Seek to sample - adapted from libFLAC 1.1.3b2+ */
 235 bool flac_seek(FLACContext* fc, uint32_t target_sample) {
 236     off_t orig_pos = ci->curpos;
 237     off_t pos = -1;
 238     unsigned long lower_bound, upper_bound;
 239     unsigned long lower_bound_sample, upper_bound_sample;
 240     int i;
 241     unsigned approx_bytes_per_frame;
 242     uint32_t this_frame_sample = fc->samplenumber;
 243     unsigned this_block_size = fc->blocksize;
 244     bool needs_seek = true, first_seek = true;
 245
 246     /* We are just guessing here. */
 247     if(fc->max_framesize > 0)
 248         approx_bytes_per_frame = (fc->max_framesize + fc->min_framesize)/2 + 1;
 249     /* Check if it's a known fixed-blocksize stream. */
 250     else if(fc->min_blocksize == fc->max_blocksize && fc->min_blocksize > 0)
 251         approx_bytes_per_frame = fc->min_blocksize*fc->channels*fc->bps/8 + 64;
 252     else
 253         approx_bytes_per_frame = 4608 * fc->channels * fc->bps/8 + 64;
 254
 255     /* Set an upper and lower bound on where in the stream we will search. */
 256     lower_bound = fc->metadatalength;
 257     lower_bound_sample = 0;
 258     upper_bound = fc->filesize;
 259     upper_bound_sample = fc->totalsamples>0 ? fc->totalsamples : target_sample;
 260
 261     /* Refine the bounds if we have a seektable with suitable points. */
 262     if(nseekpoints > 0) {
 263         /* Find the closest seek point <= target_sample, if it exists. */
 264         for(i = nseekpoints-1; i >= 0; i--) {
 265             if(seekpoints[i].sample <= target_sample)
 266                 break;
 267         }
 268         if(i >= 0) { /* i.e. we found a suitable seek point... */
 269             lower_bound = fc->metadatalength + seekpoints[i].offset;
 270             lower_bound_sample = seekpoints[i].sample;
 271         }
 272
 273         /* Find the closest seek point > target_sample, if it exists. */
 274         for(i = 0; i < nseekpoints; i++) {
 275             if(seekpoints[i].sample > target_sample)
 276                 break;
 277         }
 278         if(i < nseekpoints) { /* i.e. we found a suitable seek point... */
 279             upper_bound = fc->metadatalength + seekpoints[i].offset;
 280             upper_bound_sample = seekpoints[i].sample;
 281         }
 282     }
 283
 284     while(1) {
 285         /* Check if bounds are still ok. */
 286         if(lower_bound_sample >= upper_bound_sample ||
 287            lower_bound > upper_bound) {
 288             return false;
 289         }
 290
 291         /* Calculate new seek position */
 292         if(needs_seek) {
 293             pos = (off_t)(lower_bound +
 294               (((target_sample - lower_bound_sample) *
 295               (int64_t)(upper_bound - lower_bound)) /
 296               (upper_bound_sample - lower_bound_sample)) -
 297               approx_bytes_per_frame);
 298
 299             if(pos >= (off_t)upper_bound)
 300                 pos = (off_t)upper_bound-1;
 301             if(pos < (off_t)lower_bound)
 302                 pos = (off_t)lower_bound;
 303         }
 304
 305         if(!ci->seek_buffer(pos))
 306             return false;
 307
 308         bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 309         init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 310
 311         /* Now we need to get a frame.  It is possible for our seek
 312          * to land in the middle of audio data that looks exactly like
 313          * a frame header from a future version of an encoder.  When
 314          * that happens, frame_sync() will return false.
 315          * But there is a remote possibility that it is properly
 316          * synced at such a "future-codec frame", so to make sure,
 317          * we wait to see several "unparseable" errors in a row before
 318          * bailing out.
 319          */
 320         {
 321             unsigned unparseable_count;
 322             bool got_a_frame = false;
 323             for(unparseable_count = 0; !got_a_frame
 324                 && unparseable_count < 10; unparseable_count++) {
 325                 if(frame_sync(fc))
 326                     got_a_frame = true;
 327             }
 328             if(!got_a_frame) {
 329                 ci->seek_buffer(orig_pos);
 330                 return false;
 331             }
 332         }
 333
 334         this_frame_sample = fc->samplenumber;
 335         this_block_size = fc->blocksize;
 336
 337         if(target_sample >= this_frame_sample
 338            && target_sample < this_frame_sample+this_block_size) {
 339             /* Found the frame containing the target sample. */
 340             fc->sample_skip = target_sample - this_frame_sample;
 341             break;
 342         }
 343
 344         if(this_frame_sample + this_block_size >= upper_bound_sample &&
 345            !first_seek) {
 346             if(pos == (off_t)lower_bound || !needs_seek) {
 347                 ci->seek_buffer(orig_pos);
 348                 return false;
 349             }
 350             /* Our last move backwards wasn't big enough, try again. */
 351             approx_bytes_per_frame *= 2;
 352             continue;
 353         }
 354         /* Allow one seek over upper bound,
 355          * required for streams with unknown total samples.
 356          */
 357         first_seek = false;
 358
 359         /* Make sure we are not seeking in a corrupted stream */
 360         if(this_frame_sample < lower_bound_sample) {
 361             ci->seek_buffer(orig_pos);
 362             return false;
 363         }
 364
 365         approx_bytes_per_frame = this_block_size*fc->channels*fc->bps/8 + 64;
 366
 367         /* We need to narrow the search. */
 368         if(target_sample < this_frame_sample) {
 369             upper_bound_sample = this_frame_sample;
 370             upper_bound = ci->curpos;
 371         }
 372         else { /* Target is beyond this frame. */
 373             /* We are close, continue in decoding next frames. */
 374             if(target_sample < this_frame_sample + 4*this_block_size) {
 375                 pos = ci->curpos + fc->framesize;
 376                 needs_seek = false;
 377             }
 378
 379             lower_bound_sample = this_frame_sample + this_block_size;
 380             lower_bound = ci->curpos + fc->framesize;
 381         }
 382     }
 383
 384     return true;
 385 }
 386
 387 /* Seek to file offset */
 388 bool flac_seek_offset(FLACContext* fc, uint32_t offset) {
 389     unsigned unparseable_count;
 390     bool got_a_frame = false;
 391
 392     if(!ci->seek_buffer(offset))
 393         return false;
 394
 395     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE);
 396     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 397
 398     for(unparseable_count = 0; !got_a_frame
 399         && unparseable_count < 10; unparseable_count++) {
 400         if(frame_sync(fc))
 401             got_a_frame = true;
 402     }
 403
 404     if(!got_a_frame) {
 405         ci->seek_buffer(fc->metadatalength);
 406         return false;
 407     }
 408
 409     return true;
 410 }
 411
 412 /* this is the codec entry point */
 413 enum codec_status codec_main(void)
 414 {
 415     int8_t *buf;
 416     FLACContext fc;
 417     uint32_t samplesdone = 0;
 418     uint32_t elapsedtime;
 419     size_t bytesleft;
 420     int consumed;
 421     int res;
 422     int frame;
 423     int retval;
 424
 425     /* Generic codec initialisation */
 426     ci->configure(CODEC_SET_FILEBUF_WATERMARK, 1024*512);
 427
 428     ci->configure(DSP_SET_SAMPLE_DEPTH, FLAC_OUTPUT_DEPTH-1);
 429
 430     next_track:
 431
 432     /* Need to save offset for later use (cleared indirectly by flac_init) */
 433     samplesdone=ci->id3->offset;
 434
 435     if (codec_init()) {
 436         LOGF("FLAC: Error initialising codec\n");
 437         retval = CODEC_ERROR;
 438         goto exit;
 439     }
 440
 441     while (!*ci->taginfo_ready && !ci->stop_codec)
 442         ci->sleep(1);
 443
 444     if (!flac_init(&fc,ci->id3->first_frame_offset)) {
 445         LOGF("FLAC: Error initialising codec\n");
 446         retval = CODEC_ERROR;
 447         goto done;
 448     }
 449
 450     ci->configure(DSP_SWITCH_FREQUENCY, ci->id3->frequency);
 451     ci->configure(DSP_SET_STEREO_MODE, fc.channels == 1 ?
 452                   STEREO_MONO : STEREO_NONINTERLEAVED);
 453     codec_set_replaygain(ci->id3);
 454
 455     if (samplesdone) {
 456         flac_seek_offset(&fc, samplesdone);
 457         samplesdone=0;
 458     }
 459
 460     /* The main decoding loop */
 461     frame=0;
 462     buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 463     while (bytesleft) {
 464         ci->yield();
 465         if (ci->stop_codec || ci->new_track) {
 466             break;
 467         }
 468
 469         /* Deal with any pending seek requests */
 470         if (ci->seek_time) {
 471             if (flac_seek(&fc,(uint32_t)(((uint64_t)(ci->seek_time-1)
 472                 *ci->id3->frequency)/1000))) {
 473                 /* Refill the input buffer */
 474                 buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 475             }
 476             ci->seek_complete();
 477         }
 478
 479         if((res=flac_decode_frame(&fc,decoded0,decoded1,buf,
 480                              bytesleft,ci->yield)) < 0) {
 481              LOGF("FLAC: Frame %d, error %d\n",frame,res);
 482              retval = CODEC_ERROR;
 483              goto done;
 484         }
 485         consumed=fc.gb.index/8;
 486         frame++;
 487
 488         ci->yield();
 489         ci->pcmbuf_insert(&decoded0[fc.sample_skip], &decoded1[fc.sample_skip],
 490                           fc.blocksize - fc.sample_skip);
 491
 492         fc.sample_skip = 0;
 493
 494         /* Update the elapsed-time indicator */
 495         samplesdone=fc.samplenumber+fc.blocksize;
 496         elapsedtime=(samplesdone*10)/(ci->id3->frequency/100);
 497         ci->set_elapsed(elapsedtime);
 498
 499         ci->advance_buffer(consumed);
 500
 501         buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 502     }
 503     retval = CODEC_OK;
 504
 505 done:
 506     LOGF("FLAC: Decoded %ld samples\n",samplesdone);
 507
 508     if (ci->request_next_track())
 509         goto next_track;
 510
 511 exit:
 512     return retval;
 513 }