firmware/mp3data.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2002 by Daniel Stenberg
  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 /*
  21  * Parts of this code has been stolen from the Ample project and was written
  22  * by David Härdeman. It has since been extended and enhanced pretty much by
  23  * all sorts of friendly Rockbox people.
  24  *
  25  * A nice reference for MPEG header info:
  26  * http://rockbox.haxx.se/docs/mpeghdr.html
  27  *
  28  */
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <stdbool.h>
  34 #include <limits.h>
  35 #include "debug.h"
  36 #include "logf.h"
  37 #include "mp3data.h"
  38 #include "file.h"
  39 #include "buffer.h"
  40
  41 // #define DEBUG_VERBOSE
  42
  43 #define SYNC_MASK (0x7ffL << 21)
  44 #define VERSION_MASK (3L << 19)
  45 #define LAYER_MASK (3L << 17)
  46 #define PROTECTION_MASK (1L << 16)
  47 #define BITRATE_MASK (0xfL << 12)
  48 #define SAMPLERATE_MASK (3L << 10)
  49 #define PADDING_MASK (1L << 9)
  50 #define PRIVATE_MASK (1L << 8)
  51 #define CHANNELMODE_MASK (3L << 6)
  52 #define MODE_EXT_MASK (3L << 4)
  53 #define COPYRIGHT_MASK (1L << 3)
  54 #define ORIGINAL_MASK (1L << 2)
  55 #define EMPHASIS_MASK 3L
  56
  57 /* MPEG Version table, sorted by version index */
  58 static const signed char version_table[4] = {
  59     MPEG_VERSION2_5, -1, MPEG_VERSION2, MPEG_VERSION1
  60 };
  61
  62 /* Bitrate table for mpeg audio, indexed by row index and birate index */
  63 static const short bitrates[5][16] = {
  64     {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0}, /* V1 L1 */
  65     {0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,0}, /* V1 L2 */
  66     {0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,0}, /* V1 L3 */
  67     {0,32,48,56, 64, 80, 96,112,128,144,160,176,192,224,256,0}, /* V2 L1 */
  68     {0, 8,16,24, 32, 40, 48, 56, 64, 80, 96,112,128,144,160,0}  /* V2 L2+L3 */
  69 };
  70
  71 /* Bitrate pointer table, indexed by version and layer */
  72 static const short *bitrate_table[3][3] =
  73 {
  74     {bitrates[0], bitrates[1], bitrates[2]},
  75     {bitrates[3], bitrates[4], bitrates[4]},
  76     {bitrates[3], bitrates[4], bitrates[4]}
  77 };
  78
  79 /* Sampling frequency table, indexed by version and frequency index */
  80 static const unsigned short freq_table[3][3] =
  81 {
  82     {44100, 48000, 32000}, /* MPEG Version 1 */
  83     {22050, 24000, 16000}, /* MPEG version 2 */
  84     {11025, 12000,  8000}, /* MPEG version 2.5 */
  85 };
  86
  87 unsigned long bytes2int(unsigned long b0,
  88                      unsigned long b1,
  89                      unsigned long b2,
  90                      unsigned long b3)
  91 {
  92    return (((long)(b0 & 0xFF) << (3*8)) |
  93            ((long)(b1 & 0xFF) << (2*8)) |
  94            ((long)(b2 & 0xFF) << (1*8)) |
  95            ((long)(b3 & 0xFF) << (0*8)));
  96 }
  97
  98 /* check if 'head' is a valid mp3 frame header */
  99 static bool is_mp3frameheader(unsigned long head)
 100 {
 101     if ((head & SYNC_MASK) != (unsigned long)SYNC_MASK) /* bad sync? */
 102         return false;
 103     if ((head & VERSION_MASK) == (1L << 19)) /* bad version? */
 104         return false;
 105     if (!(head & LAYER_MASK)) /* no layer? */
 106         return false;
 107 #if CONFIG_CODEC != SWCODEC
 108     /* The MAS can't decode layer 1, so treat layer 1 data as invalid */
 109     if ((head & LAYER_MASK) == LAYER_MASK)
 110         return false;
 111 #endif
 112     if ((head & BITRATE_MASK) == BITRATE_MASK) /* bad bitrate? */
 113         return false;
 114     if (!(head & BITRATE_MASK)) /* no bitrate? */
 115         return false;
 116     if ((head & SAMPLERATE_MASK) == SAMPLERATE_MASK) /* bad sample rate? */
 117         return false;
 118
 119     return true;
 120 }
 121
 122 static bool mp3headerinfo(struct mp3info *info, unsigned long header)
 123 {
 124     int bitindex, freqindex;
 125
 126     /* MPEG Audio Version */
 127     if ((header & VERSION_MASK) >> 19 >= sizeof(version_table))
 128         return false;
 129
 130     info->version = version_table[(header & VERSION_MASK) >> 19];
 131     if (info->version < 0)
 132         return false;
 133
 134     /* Layer */
 135     info->layer = 3 - ((header & LAYER_MASK) >> 17);
 136     if (info->layer == 3)
 137         return false;
 138
 139     info->protection = (header & PROTECTION_MASK) ? true : false;
 140
 141     /* Bitrate */
 142     bitindex = (header & BITRATE_MASK) >> 12;
 143     info->bitrate = bitrate_table[info->version][info->layer][bitindex];
 144     if(info->bitrate == 0)
 145         return false;
 146
 147     /* Sampling frequency */
 148     freqindex = (header & SAMPLERATE_MASK) >> 10;
 149     if (freqindex == 3)
 150         return false;
 151     info->frequency = freq_table[info->version][freqindex];
 152
 153     info->padding = (header & PADDING_MASK) ? 1 : 0;
 154
 155     /* Calculate number of bytes, calculation depends on layer */
 156     if (info->layer == 0) {
 157         info->frame_samples = 384;
 158         info->frame_size = (12000 * info->bitrate / info->frequency
 159                             + info->padding) * 4;
 160     }
 161     else {
 162         if ((info->version > MPEG_VERSION1) && (info->layer == 2))
 163             info->frame_samples = 576;
 164         else
 165             info->frame_samples = 1152;
 166         info->frame_size = (1000/8) * info->frame_samples * info->bitrate
 167                            / info->frequency + info->padding;
 168     }
 169
 170     /* Frametime fraction denominator */
 171     if (freqindex != 0) {      /* 48/32/24/16/12/8 kHz */
 172         info->ft_den = 1;      /* integer number of milliseconds */
 173     }
 174     else {                     /* 44.1/22.05/11.025 kHz */
 175         if (info->layer == 0)     /* layer 1 */
 176             info->ft_den = 147;
 177         else                      /* layer 2+3 */
 178             info->ft_den = 49;
 179     }
 180     /* Frametime fraction numerator */
 181     info->ft_num = 1000 * info->ft_den * info->frame_samples / info->frequency;
 182
 183     info->channel_mode = (header & CHANNELMODE_MASK) >> 6;
 184     info->mode_extension = (header & MODE_EXT_MASK) >> 4;
 185     info->emphasis = header & EMPHASIS_MASK;
 186
 187 #ifdef DEBUG_VERBOSE
 188     DEBUGF( "Header: %08lx, Ver %d, lay %d, bitr %d, freq %ld, "
 189             "chmode %d, mode_ext %d, emph %d, bytes: %d time: %d/%d\n",
 190             header, info->version, info->layer+1, info->bitrate,
 191             info->frequency, info->channel_mode, info->mode_extension,
 192             info->emphasis, info->frame_size, info->ft_num, info->ft_den);
 193 #endif
 194     return true;
 195 }
 196
 197 static unsigned long __find_next_frame(int fd, long *offset, long max_offset,
 198                                        unsigned long last_header,
 199                                        int(*getfunc)(int fd, unsigned char *c))
 200 {
 201     unsigned long header=0;
 202     unsigned char tmp;
 203     int i;
 204
 205     long pos = 0;
 206
 207     /* We remember the last header we found, to use as a template to see if
 208        the header we find has the same frequency, layer etc */
 209     last_header &= 0xffff0c00;
 210
 211     /* Fill up header with first 24 bits */
 212     for(i = 0; i < 3; i++) {
 213         header <<= 8;
 214         if(!getfunc(fd, &tmp))
 215             return 0;
 216         header |= tmp;
 217         pos++;
 218     }
 219
 220     do {
 221         header <<= 8;
 222         if(!getfunc(fd, &tmp))
 223             return 0;
 224         header |= tmp;
 225         pos++;
 226         if(max_offset > 0 && pos > max_offset)
 227             return 0;
 228     } while(!is_mp3frameheader(header) ||
 229             (last_header?((header & 0xffff0c00) != last_header):false));
 230
 231     *offset = pos - 4;
 232
 233 #if defined(DEBUG)
 234     if(*offset)
 235         DEBUGF("Warning: skipping %ld bytes of garbage\n", *offset);
 236 #endif
 237
 238     return header;
 239 }
 240
 241 static int fileread(int fd, unsigned char *c)
 242 {
 243     return read(fd, c, 1);
 244 }
 245
 246 unsigned long find_next_frame(int fd, long *offset, long max_offset, unsigned long last_header)
 247 {
 248     return __find_next_frame(fd, offset, max_offset, last_header, fileread);
 249 }
 250
 251 #ifndef __PCTOOL__
 252 static int fnf_read_index;
 253 static int fnf_buf_len;
 254
 255 static int buf_getbyte(int fd, unsigned char *c)
 256 {
 257     if(fnf_read_index < fnf_buf_len)
 258     {
 259         *c = audiobuf[fnf_read_index++];
 260         return 1;
 261     }
 262     else
 263     {
 264         fnf_buf_len = read(fd, audiobuf, audiobufend - audiobuf);
 265         if(fnf_buf_len < 0)
 266             return -1;
 267
 268         fnf_read_index = 0;
 269
 270         if(fnf_buf_len > 0)
 271         {
 272             *c = audiobuf[fnf_read_index++];
 273             return 1;
 274         }
 275         else
 276             return 0;
 277     }
 278     return 0;
 279 }
 280
 281 static int buf_seek(int fd, int len)
 282 {
 283     fnf_read_index += len;
 284     if(fnf_read_index > fnf_buf_len)
 285     {
 286         len = fnf_read_index - fnf_buf_len;
 287
 288         fnf_buf_len = read(fd, audiobuf, audiobufend - audiobuf);
 289         if(fnf_buf_len < 0)
 290             return -1;
 291
 292         fnf_read_index = 0;
 293         fnf_read_index += len;
 294     }
 295
 296     if(fnf_read_index > fnf_buf_len)
 297     {
 298         return -1;
 299     }
 300     else
 301         return 0;
 302 }
 303
 304 static void buf_init(void)
 305 {
 306     fnf_buf_len = 0;
 307     fnf_read_index = 0;
 308 }
 309
 310 static unsigned long buf_find_next_frame(int fd, long *offset, long max_offset,
 311                                          unsigned long last_header)
 312 {
 313     return __find_next_frame(fd, offset, max_offset, last_header, buf_getbyte);
 314 }
 315
 316 static int audiobuflen;
 317 static int mem_pos;
 318 static int mem_cnt;
 319 static int mem_maxlen;
 320
 321 static int mem_getbyte(int dummy, unsigned char *c)
 322 {
 323     dummy = dummy;
 324
 325     *c = audiobuf[mem_pos++];
 326     if(mem_pos >= audiobuflen)
 327         mem_pos = 0;
 328
 329     if(mem_cnt++ >= mem_maxlen)
 330         return 0;
 331     else
 332         return 1;
 333 }
 334
 335 unsigned long mem_find_next_frame(int startpos, long *offset, long max_offset,
 336                                   unsigned long last_header)
 337 {
 338     audiobuflen = audiobufend - audiobuf;
 339     mem_pos = startpos;
 340     mem_cnt = 0;
 341     mem_maxlen = max_offset;
 342
 343     return __find_next_frame(0, offset, max_offset, last_header, mem_getbyte);
 344 }
 345 #endif
 346
 347 int get_mp3file_info(int fd, struct mp3info *info)
 348 {
 349     unsigned char frame[1800];
 350     unsigned char *vbrheader;
 351     unsigned long header;
 352     long bytecount;
 353     int num_offsets;
 354     int frames_per_entry;
 355     int i;
 356     long offset;
 357     int j;
 358     long tmp;
 359
 360     header = find_next_frame(fd, &bytecount, 0x20000, 0);
 361     /* Quit if we haven't found a valid header within 128K */
 362     if(header == 0)
 363         return -1;
 364
 365     memset(info, 0, sizeof(struct mp3info));
 366 #if CONFIG_CODEC==SWCODEC
 367     /* These two are needed for proper LAME gapless MP3 playback */
 368     info->enc_delay = -1;
 369     info->enc_padding = -1;
 370 #endif
 371     if(!mp3headerinfo(info, header))
 372         return -2;
 373
 374     /* OK, we have found a frame. Let's see if it has a Xing header */
 375     if (info->frame_size-4 >= (int)sizeof(frame))
 376     {
 377 #if defined(DEBUG)
 378         DEBUGF("Error: Invalid id3 header, frame_size: %d\n", info->frame_size);
 379 #endif
 380         return -8;
 381     }
 382
 383     if(read(fd, frame, info->frame_size-4) < 0)
 384         return -3;
 385
 386     /* calculate position of VBR header */
 387     if ( info->version == MPEG_VERSION1 ) {
 388         if (info->channel_mode == 3) /* mono */
 389             vbrheader = frame + 17;
 390         else
 391             vbrheader = frame + 32;
 392     }
 393     else {
 394         if (info->channel_mode == 3) /* mono */
 395             vbrheader = frame + 9;
 396         else
 397             vbrheader = frame + 17;
 398     }
 399
 400     if (!memcmp(vbrheader, "Xing", 4)
 401         || !memcmp(vbrheader, "Info", 4))
 402     {
 403         int i = 8; /* Where to start parsing info */
 404
 405         /* DEBUGF("Xing/Info header\n"); */
 406
 407         /* Remember where in the file the Xing header is */
 408         info->vbr_header_pos = lseek(fd, 0, SEEK_CUR) - info->frame_size;
 409
 410         /* We want to skip the Xing frame when playing the stream */
 411         bytecount += info->frame_size;
 412
 413         /* Now get the next frame to find out the real info about
 414            the mp3 stream */
 415         header = find_next_frame(fd, &tmp, 0x20000, 0);
 416         if(header == 0)
 417             return -4;
 418
 419         if(!mp3headerinfo(info, header))
 420             return -5;
 421
 422         /* Is it a VBR file? */
 423         info->is_vbr = info->is_xing_vbr = !memcmp(vbrheader, "Xing", 4);
 424
 425         if (vbrheader[7] & VBR_FRAMES_FLAG) /* Is the frame count there? */
 426         {
 427             info->frame_count = bytes2int(vbrheader[i], vbrheader[i+1],
 428                                           vbrheader[i+2], vbrheader[i+3]);
 429             if (info->frame_count <= ULONG_MAX / info->ft_num)
 430                 info->file_time = info->frame_count * info->ft_num / info->ft_den;
 431             else
 432                 info->file_time = info->frame_count / info->ft_den * info->ft_num;
 433             i += 4;
 434         }
 435
 436         if (vbrheader[7] & VBR_BYTES_FLAG) /* Is byte count there? */
 437         {
 438             info->byte_count = bytes2int(vbrheader[i], vbrheader[i+1],
 439                                          vbrheader[i+2], vbrheader[i+3]);
 440             i += 4;
 441         }
 442
 443         if (info->file_time && info->byte_count)
 444         {
 445             if (info->byte_count <= (ULONG_MAX/8))
 446                 info->bitrate = info->byte_count * 8 / info->file_time;
 447             else
 448                 info->bitrate = info->byte_count / (info->file_time >> 3);
 449         }
 450         else
 451             info->bitrate = 0;
 452
 453         if (vbrheader[7] & VBR_TOC_FLAG) /* Is table-of-contents there? */
 454         {
 455             info->has_toc = true;
 456             memcpy( info->toc, vbrheader+i, 100 );
 457             i += 100;
 458         }
 459         if (vbrheader[7] & VBR_QUALITY_FLAG)
 460         {
 461             /* We don't care about this, but need to skip it */
 462             i += 4;
 463         }
 464 #if CONFIG_CODEC==SWCODEC
 465         i += 21;
 466         info->enc_delay = (vbrheader[i] << 4) | (vbrheader[i + 1] >> 4);
 467         info->enc_padding = ((vbrheader[i + 1] & 0x0f) << 8) | vbrheader[i + 2];
 468         /* TODO: This sanity checking is rather silly, seeing as how the LAME
 469            header contains a CRC field that can be used to verify integrity. */
 470         if (!(info->enc_delay >= 0 && info->enc_delay <= 2880 &&
 471             info->enc_padding >= 0 && info->enc_padding <= 2*1152))
 472         {
 473            /* Invalid data */
 474            info->enc_delay = -1;
 475            info->enc_padding = -1;
 476         }
 477 #endif
 478     }
 479
 480     if (!memcmp(vbrheader, "VBRI", 4))
 481     {
 482         DEBUGF("VBRI header\n");
 483
 484         /* We want to skip the VBRI frame when playing the stream */
 485         bytecount += info->frame_size;
 486
 487         /* Now get the next frame to find out the real info about
 488            the mp3 stream */
 489         header = find_next_frame(fd, &tmp, 0x20000, 0);
 490         if(header == 0)
 491             return -6;
 492
 493         bytecount += tmp;
 494
 495         if(!mp3headerinfo(info, header))
 496             return -7;
 497
 498         DEBUGF("%04x: %04x %04x ", 0, (short)(header >> 16),
 499                (short)(header & 0xffff));
 500         for(i = 4;i < (int)sizeof(frame)-4;i+=2) {
 501             if(i % 16 == 0) {
 502                 DEBUGF("\n%04x: ", i-4);
 503             }
 504             DEBUGF("%04x ", (frame[i-4] << 8) | frame[i-4+1]);
 505         }
 506
 507         DEBUGF("\n");
 508
 509         /* Yes, it is a FhG VBR file */
 510         info->is_vbr = true;
 511         info->is_vbri_vbr = true;
 512         info->has_toc = false; /* We don't parse the TOC (yet) */
 513
 514         info->byte_count = bytes2int(vbrheader[10], vbrheader[11],
 515                                      vbrheader[12], vbrheader[13]);
 516         info->frame_count = bytes2int(vbrheader[14], vbrheader[15],
 517                                       vbrheader[16], vbrheader[17]);
 518         if (info->frame_count <= ULONG_MAX / info->ft_num)
 519             info->file_time = info->frame_count * info->ft_num / info->ft_den;
 520         else
 521             info->file_time = info->frame_count / info->ft_den * info->ft_num;
 522
 523         if (info->byte_count <= (ULONG_MAX/8))
 524             info->bitrate = info->byte_count * 8 / info->file_time;
 525         else
 526             info->bitrate = info->byte_count / (info->file_time >> 3);
 527
 528         /* We don't parse the TOC, since we don't yet know how to (FIXME) */
 529         num_offsets = bytes2int(0, 0, vbrheader[18], vbrheader[19]);
 530         frames_per_entry = bytes2int(0, 0, vbrheader[24], vbrheader[25]);
 531         DEBUGF("Frame size (%dkpbs): %d bytes (0x%x)\n",
 532                info->bitrate, info->frame_size, info->frame_size);
 533         DEBUGF("Frame count: %lx\n", info->frame_count);
 534         DEBUGF("Byte count: %lx\n", info->byte_count);
 535         DEBUGF("Offsets: %d\n", num_offsets);
 536         DEBUGF("Frames/entry: %d\n", frames_per_entry);
 537
 538         offset = 0;
 539
 540         for(i = 0;i < num_offsets;i++)
 541         {
 542            j = bytes2int(0, 0, vbrheader[26+i*2], vbrheader[27+i*2]);
 543            offset += j;
 544            DEBUGF("%03d: %lx (%x)\n", i, offset - bytecount, j);
 545         }
 546     }
 547
 548     return bytecount;
 549 }
 550
 551 static void long2bytes(unsigned char *buf, long val)
 552 {
 553     buf[0] = (val >> 24) & 0xff;
 554     buf[1] = (val >> 16) & 0xff;
 555     buf[2] = (val >> 8) & 0xff;
 556     buf[3] = val & 0xff;
 557 }
 558
 559 #ifndef __PCTOOL__
 560 int count_mp3_frames(int fd, int startpos, int filesize,
 561                      void (*progressfunc)(int))
 562 {
 563     unsigned long header = 0;
 564     struct mp3info info;
 565     int num_frames;
 566     long bytes;
 567     int cnt;
 568     long progress_chunk = filesize / 50; /* Max is 50%, in 1% increments */
 569     int progress_cnt = 0;
 570     bool is_vbr = false;
 571     int last_bitrate = 0;
 572     int header_template = 0;
 573
 574     if(lseek(fd, startpos, SEEK_SET) < 0)
 575         return -1;
 576
 577     buf_init();
 578
 579     /* Find out the total number of frames */
 580     num_frames = 0;
 581     cnt = 0;
 582
 583     while((header = buf_find_next_frame(fd, &bytes, -1, header_template))) {
 584         mp3headerinfo(&info, header);
 585
 586         if(!header_template)
 587             header_template = header;
 588
 589         /* See if this really is a VBR file */
 590         if(last_bitrate && info.bitrate != last_bitrate)
 591         {
 592             is_vbr = true;
 593         }
 594         last_bitrate = info.bitrate;
 595
 596         buf_seek(fd, info.frame_size-4);
 597         num_frames++;
 598         if(progressfunc)
 599         {
 600             cnt += bytes + info.frame_size;
 601             if(cnt > progress_chunk)
 602             {
 603                 progress_cnt++;
 604                 progressfunc(progress_cnt);
 605                 cnt = 0;
 606             }
 607         }
 608     }
 609     DEBUGF("Total number of frames: %d\n", num_frames);
 610
 611     if(is_vbr)
 612         return num_frames;
 613     else
 614     {
 615         DEBUGF("Not a VBR file\n");
 616         return 0;
 617     }
 618 }
 619
 620 static const char cooltext[] = "Rockbox - rocks your box";
 621
 622 /* buf needs to be the audio buffer with TOC generation enabled,
 623    and at least MAX_XING_HEADER_SIZE bytes otherwise */
 624 int create_xing_header(int fd, long startpos, long filesize,
 625                        unsigned char *buf, unsigned long num_frames,
 626                        unsigned long rec_time, unsigned long header_template,
 627                        void (*progressfunc)(int), bool generate_toc)
 628 {
 629     struct mp3info info;
 630     unsigned char toc[100];
 631     unsigned long header = 0;
 632     unsigned long xing_header_template = header_template;
 633     unsigned long filepos;
 634     long pos, last_pos;
 635     long j;
 636     long bytes;
 637     int i;
 638     int index;
 639
 640     DEBUGF("create_xing_header()\n");
 641
 642     if(generate_toc)
 643     {
 644         lseek(fd, startpos, SEEK_SET);
 645         buf_init();
 646
 647         /* Generate filepos table */
 648         last_pos = 0;
 649         filepos = 0;
 650         header = 0;
 651         for(i = 0;i < 100;i++) {
 652             /* Calculate the absolute frame number for this seek point */
 653             pos = i * num_frames / 100;
 654
 655             /* Advance from the last seek point to this one */
 656             for(j = 0;j < pos - last_pos;j++)
 657             {
 658                 header = buf_find_next_frame(fd, &bytes, -1, header_template);
 659                 filepos += bytes;
 660                 mp3headerinfo(&info, header);
 661                 buf_seek(fd, info.frame_size-4);
 662                 filepos += info.frame_size;
 663
 664                 if(!header_template)
 665                     header_template = header;
 666             }
 667
 668             /* Save a header for later use if header_template is empty.
 669                We only save one header, and we want to save one in the
 670                middle of the stream, just in case the first and the last
 671                headers are corrupt. */
 672             if(!xing_header_template && i == 1)
 673                 xing_header_template = header;
 674
 675             if(progressfunc)
 676             {
 677                 progressfunc(50 + i/2);
 678             }
 679
 680             /* Fill in the TOC entry */
 681             /* each toc is a single byte indicating how many 256ths of the
 682              * way through the file, is that percent of the way through the
 683              * song. the easy method, filepos*256/filesize, chokes when
 684              * the upper 8 bits of the file position are nonzero
 685              * (i.e. files over 16mb in size).
 686              */
 687             if (filepos > (ULONG_MAX/256))
 688             {
 689                 /* instead of multiplying filepos by 256, we divide
 690                  * filesize by 256.
 691                  */
 692                 toc[i] = filepos / (filesize >> 8);
 693             }
 694             else
 695             {
 696                 toc[i] = filepos * 256 / filesize;
 697             }
 698
 699             DEBUGF("Pos %d: %ld  relpos: %ld  filepos: %lx tocentry: %x\n",
 700                    i, pos, pos-last_pos, filepos, toc[i]);
 701
 702             last_pos = pos;
 703         }
 704     }
 705
 706     /* Use the template header and create a new one.
 707        We ignore the Protection bit even if the rest of the stream is
 708        protected. */
 709     header = xing_header_template & ~(BITRATE_MASK|PROTECTION_MASK|PADDING_MASK);
 710     header |= 8 << 12; /* This gives us plenty of space, 192..576 bytes */
 711
 712     if (!mp3headerinfo(&info, header))
 713         return 0;  /* invalid header */
 714
 715     if (num_frames == 0 && rec_time) {
 716         /* estimate the number of frames based on the recording time */
 717         if (rec_time <= ULONG_MAX / info.ft_den)
 718             num_frames = rec_time * info.ft_den / info.ft_num;
 719         else
 720             num_frames = rec_time / info.ft_num * info.ft_den;
 721     }
 722
 723     /* Clear the frame */
 724     memset(buf, 0, MAX_XING_HEADER_SIZE);
 725
 726     /* Write the header to the buffer */
 727     long2bytes(buf, header);
 728
 729     /* Calculate position of VBR header */
 730     if (info.version == MPEG_VERSION1) {
 731         if (info.channel_mode == 3) /* mono */
 732             index = 21;
 733         else
 734             index = 36;
 735     }
 736     else {
 737         if (info.channel_mode == 3) /* mono */
 738             index = 13;
 739         else
 740             index = 21;
 741     }
 742
 743     /* Create the Xing data */
 744     memcpy(&buf[index], "Xing", 4);
 745     long2bytes(&buf[index+4], (num_frames ? VBR_FRAMES_FLAG : 0)
 746                               | (filesize ? VBR_BYTES_FLAG : 0)
 747                               | (generate_toc ? VBR_TOC_FLAG : 0));
 748     index += 8;
 749     if(num_frames)
 750     {
 751         long2bytes(&buf[index], num_frames);
 752         index += 4;
 753     }
 754
 755     if(filesize)
 756     {
 757         long2bytes(&buf[index], filesize - startpos);
 758         index += 4;
 759     }
 760
 761     /* Copy the TOC */
 762     memcpy(buf + index, toc, 100);
 763
 764     /* And some extra cool info */
 765     memcpy(buf + index + 100, cooltext, sizeof(cooltext));
 766
 767 #ifdef DEBUG
 768     for(i = 0;i < info.frame_size;i++)
 769     {
 770         if(i && !(i % 16))
 771             DEBUGF("\n");
 772
 773         DEBUGF("%02x ", buf[i]);
 774     }
 775 #endif
 776
 777     return info.frame_size;
 778 }
 779
 780 #endif