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 static int32_t decoded0[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_DECODED0;
  29 static 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 static struct FLACseekpoints seekpoints[MAX_SUPPORTED_SEEKTABLE_SIZE];
  69 static 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             int max_blocksize = (buf[2] << 8) | buf[3];
 122             if (max_blocksize > MAX_BLOCKSIZE)
 123             {
 124                 LOGF("FLAC: Maximum blocksize is too large (%d > %d)\n",
 125                      max_blocksize, MAX_BLOCKSIZE);
 126                 return false;
 127             }
 128             fc->max_blocksize = max_blocksize;
 129             fc->min_framesize = (buf[4] << 16) | (buf[5] << 8) | buf[6];
 130             fc->max_framesize = (buf[7] << 16) | (buf[8] << 8) | buf[9];
 131             fc->samplerate = (buf[10] << 12) | (buf[11] << 4)
 132                              | ((buf[12] & 0xf0) >> 4);
 133             fc->channels = ((buf[12]&0x0e)>>1) + 1;
 134             fc->bps = (((buf[12]&0x01) << 4) | ((buf[13]&0xf0)>>4) ) + 1;
 135
 136             /* totalsamples is a 36-bit field, but we assume <= 32 bits are
 137                used */
 138             fc->totalsamples = (buf[14] << 24) | (buf[15] << 16)
 139                                | (buf[16] << 8) | buf[17];
 140
 141             /* Calculate track length (in ms) and estimate the bitrate
 142                (in kbit/s) */
 143             fc->length = ((int64_t) fc->totalsamples * 1000) / fc->samplerate;
 144
 145             found_streaminfo=true;
 146         } else if ((buf[0] & 0x7f) == 3) { /* 3 is the SEEKTABLE block */
 147             while ((nseekpoints < MAX_SUPPORTED_SEEKTABLE_SIZE) &&
 148                    (blocklength >= 18)) {
 149                 if (ci->read_filebuf(buf,18) < 18) return false;
 150                 blocklength-=18;
 151
 152                 seekpoint_hi=(buf[0] << 24) | (buf[1] << 16) |
 153                              (buf[2] << 8) | buf[3];
 154                 seekpoint_lo=(buf[4] << 24) | (buf[5] << 16) |
 155                              (buf[6] << 8) | buf[7];
 156                 offset_hi=(buf[8] << 24) | (buf[9] << 16) |
 157                              (buf[10] << 8) | buf[11];
 158                 offset_lo=(buf[12] << 24) | (buf[13] << 16) |
 159                              (buf[14] << 8) | buf[15];
 160
 161                 blocksize=(buf[16] << 8) | buf[17];
 162
 163                 /* Only store seekpoints where the high 32 bits are zero */
 164                 if ((seekpoint_hi == 0) && (seekpoint_lo != 0xffffffff) &&
 165                     (offset_hi == 0)) {
 166                         seekpoints[nseekpoints].sample=seekpoint_lo;
 167                         seekpoints[nseekpoints].offset=offset_lo;
 168                         seekpoints[nseekpoints].blocksize=blocksize;
 169                         nseekpoints++;
 170                 }
 171             }
 172             /* Skip any unread seekpoints */
 173             if (blocklength > 0)
 174                 ci->advance_buffer(blocklength);
 175         } else {
 176           /* Skip to next metadata block */
 177           ci->advance_buffer(blocklength);
 178         }
 179     }
 180
 181    if (found_streaminfo) {
 182        fc->bitrate = ((int64_t) (fc->filesize-fc->metadatalength) * 8)
 183                      / fc->length;
 184        return true;
 185    } else {
 186        return false;
 187    }
 188 }
 189
 190 /* Synchronize to next frame in stream - adapted from libFLAC 1.1.3b2 */
 191 static bool frame_sync(FLACContext* fc) {
 192     unsigned int x = 0;
 193     bool cached = false;
 194
 195     /* Make sure we're byte aligned. */
 196     align_get_bits(&fc->gb);
 197
 198     while(1) {
 199         if(fc->gb.size_in_bits - get_bits_count(&fc->gb) < 8) {
 200             /* Error, end of bitstream, a valid stream should never reach here
 201              * since the buffer should contain at least one frame header.
 202              */
 203             return false;
 204         }
 205
 206         if(cached)
 207             cached = false;
 208         else
 209             x = get_bits(&fc->gb, 8);
 210
 211         if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 212             x = get_bits(&fc->gb, 8);
 213             /* We have to check if we just read two 0xff's in a row; the second
 214              * may actually be the beginning of the sync code.
 215              */
 216             if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
 217                 cached = true;
 218             }
 219             else if(x >> 2 == 0x3e) { /* MAGIC NUMBER for last 6 sync bits. */
 220                 /* Succesfully synced. */
 221                 break;
 222             }
 223         }
 224     }
 225
 226     /* Advance and init bit buffer to the new frame. */
 227     ci->advance_buffer((get_bits_count(&fc->gb)-16)>>3); /* consumed bytes */
 228     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 229     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 230
 231     /* Decode the frame to verify the frame crc and
 232      * fill fc with its metadata.
 233      */
 234     if(flac_decode_frame(fc, decoded0, decoded1,
 235        bit_buffer, buff_size, ci->yield) < 0) {
 236         return false;
 237     }
 238
 239     return true;
 240 }
 241
 242 /* Seek to sample - adapted from libFLAC 1.1.3b2+ */
 243 static bool flac_seek(FLACContext* fc, uint32_t target_sample) {
 244     off_t orig_pos = ci->curpos;
 245     off_t pos = -1;
 246     unsigned long lower_bound, upper_bound;
 247     unsigned long lower_bound_sample, upper_bound_sample;
 248     int i;
 249     unsigned approx_bytes_per_frame;
 250     uint32_t this_frame_sample = fc->samplenumber;
 251     unsigned this_block_size = fc->blocksize;
 252     bool needs_seek = true, first_seek = true;
 253
 254     /* We are just guessing here. */
 255     if(fc->max_framesize > 0)
 256         approx_bytes_per_frame = (fc->max_framesize + fc->min_framesize)/2 + 1;
 257     /* Check if it's a known fixed-blocksize stream. */
 258     else if(fc->min_blocksize == fc->max_blocksize && fc->min_blocksize > 0)
 259         approx_bytes_per_frame = fc->min_blocksize*fc->channels*fc->bps/8 + 64;
 260     else
 261         approx_bytes_per_frame = 4608 * fc->channels * fc->bps/8 + 64;
 262
 263     /* Set an upper and lower bound on where in the stream we will search. */
 264     lower_bound = fc->metadatalength;
 265     lower_bound_sample = 0;
 266     upper_bound = fc->filesize;
 267     upper_bound_sample = fc->totalsamples>0 ? fc->totalsamples : target_sample;
 268
 269     /* Refine the bounds if we have a seektable with suitable points. */
 270     if(nseekpoints > 0) {
 271         /* Find the closest seek point <= target_sample, if it exists. */
 272         for(i = nseekpoints-1; i >= 0; i--) {
 273             if(seekpoints[i].sample <= target_sample)
 274                 break;
 275         }
 276         if(i >= 0) { /* i.e. we found a suitable seek point... */
 277             lower_bound = fc->metadatalength + seekpoints[i].offset;
 278             lower_bound_sample = seekpoints[i].sample;
 279         }
 280
 281         /* Find the closest seek point > target_sample, if it exists. */
 282         for(i = 0; i < nseekpoints; i++) {
 283             if(seekpoints[i].sample > target_sample)
 284                 break;
 285         }
 286         if(i < nseekpoints) { /* i.e. we found a suitable seek point... */
 287             upper_bound = fc->metadatalength + seekpoints[i].offset;
 288             upper_bound_sample = seekpoints[i].sample;
 289         }
 290     }
 291
 292     while(1) {
 293         /* Check if bounds are still ok. */
 294         if(lower_bound_sample >= upper_bound_sample ||
 295            lower_bound > upper_bound) {
 296             return false;
 297         }
 298
 299         /* Calculate new seek position */
 300         if(needs_seek) {
 301             pos = (off_t)(lower_bound +
 302               (((target_sample - lower_bound_sample) *
 303               (int64_t)(upper_bound - lower_bound)) /
 304               (upper_bound_sample - lower_bound_sample)) -
 305               approx_bytes_per_frame);
 306
 307             if(pos >= (off_t)upper_bound)
 308                 pos = (off_t)upper_bound-1;
 309             if(pos < (off_t)lower_bound)
 310                 pos = (off_t)lower_bound;
 311         }
 312
 313         if(!ci->seek_buffer(pos))
 314             return false;
 315
 316         bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
 317         init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 318
 319         /* Now we need to get a frame.  It is possible for our seek
 320          * to land in the middle of audio data that looks exactly like
 321          * a frame header from a future version of an encoder.  When
 322          * that happens, frame_sync() will return false.
 323          * But there is a remote possibility that it is properly
 324          * synced at such a "future-codec frame", so to make sure,
 325          * we wait to see several "unparseable" errors in a row before
 326          * bailing out.
 327          */
 328         {
 329             unsigned unparseable_count;
 330             bool got_a_frame = false;
 331             for(unparseable_count = 0; !got_a_frame
 332                 && unparseable_count < 10; unparseable_count++) {
 333                 if(frame_sync(fc))
 334                     got_a_frame = true;
 335             }
 336             if(!got_a_frame) {
 337                 ci->seek_buffer(orig_pos);
 338                 return false;
 339             }
 340         }
 341
 342         this_frame_sample = fc->samplenumber;
 343         this_block_size = fc->blocksize;
 344
 345         if(target_sample >= this_frame_sample
 346            && target_sample < this_frame_sample+this_block_size) {
 347             /* Found the frame containing the target sample. */
 348             fc->sample_skip = target_sample - this_frame_sample;
 349             break;
 350         }
 351
 352         if(this_frame_sample + this_block_size >= upper_bound_sample &&
 353            !first_seek) {
 354             if(pos == (off_t)lower_bound || !needs_seek) {
 355                 ci->seek_buffer(orig_pos);
 356                 return false;
 357             }
 358             /* Our last move backwards wasn't big enough, try again. */
 359             approx_bytes_per_frame *= 2;
 360             continue;
 361         }
 362         /* Allow one seek over upper bound,
 363          * required for streams with unknown total samples.
 364          */
 365         first_seek = false;
 366
 367         /* Make sure we are not seeking in a corrupted stream */
 368         if(this_frame_sample < lower_bound_sample) {
 369             ci->seek_buffer(orig_pos);
 370             return false;
 371         }
 372
 373         approx_bytes_per_frame = this_block_size*fc->channels*fc->bps/8 + 64;
 374
 375         /* We need to narrow the search. */
 376         if(target_sample < this_frame_sample) {
 377             upper_bound_sample = this_frame_sample;
 378             upper_bound = ci->curpos;
 379         }
 380         else { /* Target is beyond this frame. */
 381             /* We are close, continue in decoding next frames. */
 382             if(target_sample < this_frame_sample + 4*this_block_size) {
 383                 pos = ci->curpos + fc->framesize;
 384                 needs_seek = false;
 385             }
 386
 387             lower_bound_sample = this_frame_sample + this_block_size;
 388             lower_bound = ci->curpos + fc->framesize;
 389         }
 390     }
 391
 392     return true;
 393 }
 394
 395 /* Seek to file offset */
 396 static bool flac_seek_offset(FLACContext* fc, uint32_t offset) {
 397     unsigned unparseable_count;
 398     bool got_a_frame = false;
 399
 400     if(!ci->seek_buffer(offset))
 401         return false;
 402
 403     bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE);
 404     init_get_bits(&fc->gb, bit_buffer, buff_size*8);
 405
 406     for(unparseable_count = 0; !got_a_frame
 407         && unparseable_count < 10; unparseable_count++) {
 408         if(frame_sync(fc))
 409             got_a_frame = true;
 410     }
 411
 412     if(!got_a_frame) {
 413         ci->seek_buffer(fc->metadatalength);
 414         return false;
 415     }
 416
 417     return true;
 418 }
 419
 420 /* this is the codec entry point */
 421 enum codec_status codec_main(enum codec_entry_call_reason reason)
 422 {
 423     if (reason == CODEC_LOAD) {
 424         /* Generic codec initialisation */
 425         ci->configure(DSP_SET_SAMPLE_DEPTH, FLAC_OUTPUT_DEPTH-1);
 426     }
 427
 428     return CODEC_OK;
 429 }
 430
 431 /* this is called for each file to process */
 432 enum codec_status codec_run(void)
 433 {
 434     int8_t *buf;
 435     FLACContext fc;
 436     uint32_t samplesdone;
 437     uint32_t elapsedtime;
 438     size_t bytesleft;
 439     int consumed;
 440     int res;
 441     int frame;
 442     intptr_t param;
 443
 444     if (codec_init()) {
 445         LOGF("FLAC: Error initialising codec\n");
 446         return CODEC_ERROR;
 447     }
 448
 449     /* Need to save offset for later use (cleared indirectly by flac_init) */
 450     samplesdone = ci->id3->offset;
 451
 452     if (!flac_init(&fc,ci->id3->first_frame_offset)) {
 453         LOGF("FLAC: Error initialising codec\n");
 454         return CODEC_ERROR;
 455     }
 456
 457     ci->configure(DSP_SWITCH_FREQUENCY, ci->id3->frequency);
 458     ci->configure(DSP_SET_STEREO_MODE, fc.channels == 1 ?
 459                   STEREO_MONO : STEREO_NONINTERLEAVED);
 460     codec_set_replaygain(ci->id3);
 461
 462     flac_seek_offset(&fc, samplesdone);
 463     samplesdone=0;
 464
 465     /* The main decoding loop */
 466     frame=0;
 467     buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 468     while (bytesleft) {
 469         enum codec_command_action action = ci->get_command(&param);
 470
 471         if (action == CODEC_ACTION_HALT)
 472             break;
 473
 474         /* Deal with any pending seek requests */
 475         if (action == CODEC_ACTION_SEEK_TIME) {
 476             if (flac_seek(&fc,(uint32_t)(((uint64_t)param
 477                 *ci->id3->frequency)/1000))) {
 478                 /* Refill the input buffer */
 479                 buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 480             }
 481
 482             ci->set_elapsed(param);
 483             ci->seek_complete();
 484         }
 485
 486         if((res=flac_decode_frame(&fc,decoded0,decoded1,buf,
 487                              bytesleft,ci->yield)) < 0) {
 488              LOGF("FLAC: Frame %d, error %d\n",frame,res);
 489              return CODEC_ERROR;
 490         }
 491         consumed=fc.gb.index/8;
 492         frame++;
 493
 494         ci->yield();
 495         ci->pcmbuf_insert(&decoded0[fc.sample_skip], &decoded1[fc.sample_skip],
 496                           fc.blocksize - fc.sample_skip);
 497
 498         fc.sample_skip = 0;
 499
 500         /* Update the elapsed-time indicator */
 501         samplesdone=fc.samplenumber+fc.blocksize;
 502         elapsedtime=(samplesdone*10)/(ci->id3->frequency/100);
 503         ci->set_elapsed(elapsedtime);
 504
 505         ci->advance_buffer(consumed);
 506
 507         buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
 508     }
 509
 510     LOGF("FLAC: Decoded %lu samples\n",(unsigned long)samplesdone);
 511     return CODEC_OK;
 512 }