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 = ((int64_t) fc->totalsamples * 1000) / fc->samplerate;
 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 = ((int64_t) (fc->filesize-fc->metadatalength) * 8)
 176                      / fc->length;
 177        return true;
 178    } else {
 179        return false;
 180    }
 181 }
 182
 183 /* Synchronize to next frame in stream - adapted from libFLAC 1.1.3b2 */
 184 static bool frame_sync(FLACContext* fc) {
 185     unsigned int x = 0;
 186     bool cached = false;
 187
 188     /* Make sure we're byte aligned. */
 189     align_get_bits(&fc->gb);
 190
 191     while(1) {
 192         if(fc->gb.size_in_bits - get_bits_count(&fc->gb) < 8) {
 193             /* Error, end of bitstream, a valid stream should never reach here
 194              * since the buffer should contain at least one frame header.
 195              */
 196             return false;
 197         }
 198
 199         if(cached)
 200             cached = false;
 201         else
 202             x = get_bits(&fc->gb, 8);
 203
 204         if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 205             x = get_bits(&fc->gb, 8);
 206             /* We have to check if we just read two 0xff's in a row; the second
 207              * may actually be the beginning of the sync code.
 208              */
 209             if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 210                 cached = true;
 211             }
 212             else if(x >> 2 == 0x3e) { /* MAGIC NUMBER for last 6 sync bits. */
 213                 /* Succesfully synced. */
 214                 break;
 215             }
 216         }
 217     }
 218
 219     /* Advance and init bit buffer to the new frame. */
 220     ci->advance_buffer((get_bits_count(&fc->gb)-16)>>3); /* consumed bytes */
 221     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 222     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 223
 224     /* Decode the frame to verify the frame crc and
 225      * fill fc with its metadata.
 226      */
 227     if(flac_decode_frame(fc, decoded0, decoded1,
 228        bit_buffer, buff_size, ci->yield) < 0) {
 229         return false;
 230     }
 231
 232     return true;
 233 }
 234
 235 /* Seek to sample - adapted from libFLAC 1.1.3b2+ */
 236 static bool flac_seek(FLACContext* fc, uint32_t target_sample) {
 237     off_t orig_pos = ci->curpos;
 238     off_t pos = -1;
 239     unsigned long lower_bound, upper_bound;
 240     unsigned long lower_bound_sample, upper_bound_sample;
 241     int i;
 242     unsigned approx_bytes_per_frame;
 243     uint32_t this_frame_sample = fc->samplenumber;
 244     unsigned this_block_size = fc->blocksize;
 245     bool needs_seek = true, first_seek = true;
 246
 247     /* We are just guessing here. */
 248     if(fc->max_framesize > 0)
 249         approx_bytes_per_frame = (fc->max_framesize + fc->min_framesize)/2 + 1;
 250     /* Check if it's a known fixed-blocksize stream. */
 251     else if(fc->min_blocksize == fc->max_blocksize && fc->min_blocksize > 0)
 252         approx_bytes_per_frame = fc->min_blocksize*fc->channels*fc->bps/8 + 64;
 253     else
 254         approx_bytes_per_frame = 4608 * fc->channels * fc->bps/8 + 64;
 255
 256     /* Set an upper and lower bound on where in the stream we will search. */
 257     lower_bound = fc->metadatalength;
 258     lower_bound_sample = 0;
 259     upper_bound = fc->filesize;
 260     upper_bound_sample = fc->totalsamples>0 ? fc->totalsamples : target_sample;
 261
 262     /* Refine the bounds if we have a seektable with suitable points. */
 263     if(nseekpoints > 0) {
 264         /* Find the closest seek point <= target_sample, if it exists. */
 265         for(i = nseekpoints-1; i >= 0; i--) {
 266             if(seekpoints[i].sample <= target_sample)
 267                 break;
 268         }
 269         if(i >= 0) { /* i.e. we found a suitable seek point... */
 270             lower_bound = fc->metadatalength + seekpoints[i].offset;
 271             lower_bound_sample = seekpoints[i].sample;
 272         }
 273
 274         /* Find the closest seek point > target_sample, if it exists. */
 275         for(i = 0; i < nseekpoints; i++) {
 276             if(seekpoints[i].sample > target_sample)
 277                 break;
 278         }
 279         if(i < nseekpoints) { /* i.e. we found a suitable seek point... */
 280             upper_bound = fc->metadatalength + seekpoints[i].offset;
 281             upper_bound_sample = seekpoints[i].sample;
 282         }
 283     }
 284
 285     while(1) {
 286         /* Check if bounds are still ok. */
 287         if(lower_bound_sample >= upper_bound_sample ||
 288            lower_bound > upper_bound) {
 289             return false;
 290         }
 291
 292         /* Calculate new seek position */
 293         if(needs_seek) {
 294             pos = (off_t)(lower_bound +
 295               (((target_sample - lower_bound_sample) *
 296               (int64_t)(upper_bound - lower_bound)) /
 297               (upper_bound_sample - lower_bound_sample)) -
 298               approx_bytes_per_frame);
 299
 300             if(pos >= (off_t)upper_bound)
 301                 pos = (off_t)upper_bound-1;
 302             if(pos < (off_t)lower_bound)
 303                 pos = (off_t)lower_bound;
 304         }
 305
 306         if(!ci->seek_buffer(pos))
 307             return false;
 308
 309         bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 310         init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 311
 312         /* Now we need to get a frame.  It is possible for our seek
 313          * to land in the middle of audio data that looks exactly like
 314          * a frame header from a future version of an encoder.  When
 315          * that happens, frame_sync() will return false.
 316          * But there is a remote possibility that it is properly
 317          * synced at such a "future-codec frame", so to make sure,
 318          * we wait to see several "unparseable" errors in a row before
 319          * bailing out.
 320          */
 321         {
 322             unsigned unparseable_count;
 323             bool got_a_frame = false;
 324             for(unparseable_count = 0; !got_a_frame
 325                 && unparseable_count < 10; unparseable_count++) {
 326                 if(frame_sync(fc))
 327                     got_a_frame = true;
 328             }
 329             if(!got_a_frame) {
 330                 ci->seek_buffer(orig_pos);
 331                 return false;
 332             }
 333         }
 334
 335         this_frame_sample = fc->samplenumber;
 336         this_block_size = fc->blocksize;
 337
 338         if(target_sample >= this_frame_sample
 339            && target_sample < this_frame_sample+this_block_size) {
 340             /* Found the frame containing the target sample. */
 341             fc->sample_skip = target_sample - this_frame_sample;
 342             break;
 343         }
 344
 345         if(this_frame_sample + this_block_size >= upper_bound_sample &&
 346            !first_seek) {
 347             if(pos == (off_t)lower_bound || !needs_seek) {
 348                 ci->seek_buffer(orig_pos);
 349                 return false;
 350             }
 351             /* Our last move backwards wasn't big enough, try again. */
 352             approx_bytes_per_frame *= 2;
 353             continue;
 354         }
 355         /* Allow one seek over upper bound,
 356          * required for streams with unknown total samples.
 357          */
 358         first_seek = false;
 359
 360         /* Make sure we are not seeking in a corrupted stream */
 361         if(this_frame_sample < lower_bound_sample) {
 362             ci->seek_buffer(orig_pos);
 363             return false;
 364         }
 365
 366         approx_bytes_per_frame = this_block_size*fc->channels*fc->bps/8 + 64;
 367
 368         /* We need to narrow the search. */
 369         if(target_sample < this_frame_sample) {
 370             upper_bound_sample = this_frame_sample;
 371             upper_bound = ci->curpos;
 372         }
 373         else { /* Target is beyond this frame. */
 374             /* We are close, continue in decoding next frames. */
 375             if(target_sample < this_frame_sample + 4*this_block_size) {
 376                 pos = ci->curpos + fc->framesize;
 377                 needs_seek = false;
 378             }
 379
 380             lower_bound_sample = this_frame_sample + this_block_size;
 381             lower_bound = ci->curpos + fc->framesize;
 382         }
 383     }
 384
 385     return true;
 386 }
 387
 388 /* Seek to file offset */
 389 static bool flac_seek_offset(FLACContext* fc, uint32_t offset) {
 390     unsigned unparseable_count;
 391     bool got_a_frame = false;
 392
 393     if(!ci->seek_buffer(offset))
 394         return false;
 395
 396     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE);
 397     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 398
 399     for(unparseable_count = 0; !got_a_frame
 400         && unparseable_count < 10; unparseable_count++) {
 401         if(frame_sync(fc))
 402             got_a_frame = true;
 403     }
 404
 405     if(!got_a_frame) {
 406         ci->seek_buffer(fc->metadatalength);
 407         return false;
 408     }
 409
 410     return true;
 411 }
 412
 413 /* this is the codec entry point */
 414 enum codec_status codec_main(void)
 415 {
 416     int8_t *buf;
 417     FLACContext fc;
 418     uint32_t samplesdone = 0;
 419     uint32_t elapsedtime;
 420     size_t bytesleft;
 421     int consumed;
 422     int res;
 423     int frame;
 424     int retval;
 425
 426     /* Generic codec initialisation */
 427     ci->configure(DSP_SET_SAMPLE_DEPTH, FLAC_OUTPUT_DEPTH-1);
 428
 429     next_track:
 430
 431     /* Need to save offset for later use (cleared indirectly by flac_init) */
 432     samplesdone=ci->id3->offset;
 433
 434     if (codec_init()) {
 435         LOGF("FLAC: Error initialising codec\n");
 436         retval = CODEC_ERROR;
 437         goto exit;
 438     }
 439
 440     while (!*ci->taginfo_ready && !ci->stop_codec)
 441         ci->sleep(1);
 442
 443     if (!flac_init(&fc,ci->id3->first_frame_offset)) {
 444         LOGF("FLAC: Error initialising codec\n");
 445         retval = CODEC_ERROR;
 446         goto done;
 447     }
 448
 449     ci->configure(DSP_SWITCH_FREQUENCY, ci->id3->frequency);
 450     ci->configure(DSP_SET_STEREO_MODE, fc.channels == 1 ?
 451                   STEREO_MONO : STEREO_NONINTERLEAVED);
 452     codec_set_replaygain(ci->id3);
 453
 454     if (samplesdone) {
 455         flac_seek_offset(&fc, samplesdone);
 456         samplesdone=0;
 457     }
 458
 459     /* The main decoding loop */
 460     frame=0;
 461     buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 462     while (bytesleft) {
 463         ci->yield();
 464         if (ci->stop_codec || ci->new_track) {
 465             break;
 466         }
 467
 468         /* Deal with any pending seek requests */
 469         if (ci->seek_time) {
 470             if (flac_seek(&fc,(uint32_t)(((uint64_t)(ci->seek_time-1)
 471                 *ci->id3->frequency)/1000))) {
 472                 /* Refill the input buffer */
 473                 buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 474             }
 475             ci->seek_complete();
 476         }
 477
 478         if((res=flac_decode_frame(&fc,decoded0,decoded1,buf,
 479                              bytesleft,ci->yield)) < 0) {
 480              LOGF("FLAC: Frame %d, error %d\n",frame,res);
 481              retval = CODEC_ERROR;
 482              goto done;
 483         }
 484         consumed=fc.gb.index/8;
 485         frame++;
 486
 487         ci->yield();
 488         ci->pcmbuf_insert(&decoded0[fc.sample_skip], &decoded1[fc.sample_skip],
 489                           fc.blocksize - fc.sample_skip);
 490
 491         fc.sample_skip = 0;
 492
 493         /* Update the elapsed-time indicator */
 494         samplesdone=fc.samplenumber+fc.blocksize;
 495         elapsedtime=(samplesdone*10)/(ci->id3->frequency/100);
 496         ci->set_elapsed(elapsedtime);
 497
 498         ci->advance_buffer(consumed);
 499
 500         buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 501     }
 502     retval = CODEC_OK;
 503
 504 done:
 505     LOGF("FLAC: Decoded %lu samples\n",(unsigned long)samplesdone);
 506
 507     if (ci->request_next_track())
 508         goto next_track;
 509
 510 exit:
 511     return retval;
 512 }