mp3_afh.c

   1 /*
   2  * Copyright (C) 2003-2008 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file mp3_afh.c para_server's mp3 audio format handler */
   8
   9 /*
  10  * This file is based in part on mp3tech.c and mp3tech.h, Copyright (C)
  11  * 2000-2001 Cedric Tefft <cedric@earthling.net>, which in turn is based
  12  * in part on
  13  *
  14  *      * MP3Info 0.5 by Ricardo Cerqueira <rmc@rccn.net>
  15  *      * MP3Stat 0.9 by Ed Sweetman <safemode@voicenet.com> and
  16  *                       Johannes Overmann <overmann@iname.com>
  17  */
  18
  19 #include "para.h"
  20 #include "error.h"
  21 #include "afh.h"
  22 #include "string.h"
  23 #include "afs.h"
  24 #include "server.h"
  25
  26 /** \cond some defines and structs which are only used in this file */
  27
  28 /*
  29  * MIN_CONSEC_GOOD_FRAMES defines how many consecutive valid MP3 frames we need
  30  * to see before we decide we are looking at a real MP3 file
  31  */
  32 #define MIN_CONSEC_GOOD_FRAMES 4
  33 #define FRAME_HEADER_SIZE 4
  34 #define MIN_FRAME_SIZE 21
  35
  36 struct mp3header {
  37         unsigned long sync;
  38         unsigned int version;
  39         unsigned int layer;
  40         unsigned int crc;
  41         unsigned int bitrate;
  42         unsigned int freq;
  43         unsigned int padding;
  44         unsigned int mode;
  45         unsigned int copyright;
  46         unsigned int original;
  47         unsigned int emphasis;
  48 };
  49
  50 /** \endcond */
  51 static const int frequencies[3][4] = {
  52         {22050,24000,16000,50000}, /* MPEG 2.0 */
  53         {44100,48000,32000,50000}, /* MPEG 1.0 */
  54         {11025,12000,8000,50000} /* MPEG 2.5 */
  55 };
  56
  57 static const int mp3info_bitrate[2][3][14] = {
  58 { /* MPEG 2.0 */
  59         {32,48,56,64,80,96,112,128,144,160,176,192,224,256}, /* layer 1 */
  60         {8,16,24,32,40,48,56,64,80,96,112,128,144,160}, /* layer 2 */
  61         {8,16,24,32,40,48,56,64,80,96,112,128,144,160} /* layer 3 */
  62 },
  63
  64 { /* MPEG 1.0 */
  65         {32,64,96,128,160,192,224,256,288,320,352,384,416,448}, /* layer 1 */
  66         {32,48,56,64,80,96,112,128,160,192,224,256,320,384}, /* layer 2 */
  67         {32,40,48,56,64,80,96,112,128,160,192,224,256,320} /* layer 3 */
  68 }
  69 };
  70
  71 static const int frame_size_index[] = {24000, 72000, 72000};
  72 static const char *mode_text[] = {"stereo", "joint stereo", "dual channel", "mono", "invalid"};
  73
  74 /*
  75  * Remove trailing whitespace from the end of a string
  76  */
  77 static char *unpad(char *string)
  78 {
  79         char *pos = string + strlen(string) - 1;
  80         while (para_isspace(pos[0]))
  81                 (pos--)[0] = 0;
  82         return string;
  83 }
  84
  85 static char *mp3_get_id3(unsigned char *map, size_t numbytes)
  86 {
  87         char title[31], artist[31], album[31], year[5], comment[31];
  88         off_t fpos;
  89
  90         if (numbytes < 128 || strncmp("TAG", (char *)map + numbytes - 128, 3)) {
  91                 PARA_DEBUG_LOG("no id3 v1 tag\n");
  92                 return make_message("%s: (no id3 v1 tag)\n%s:\n",
  93                         status_item_list[SI_TAGINFO1],
  94                         status_item_list[SI_TAGINFO2]);
  95         }
  96         fpos = numbytes - 125;
  97         memcpy(title, map + fpos, 30);
  98         fpos += 30;
  99         title[30] = '\0';
 100         memcpy(artist, map + fpos, 30);
 101         fpos += 30;
 102         artist[30] = '\0';
 103         memcpy(album, map + fpos, 30);
 104         fpos += 30;
 105         album[30] = '\0';
 106         memcpy(year, map + fpos, 4);
 107         fpos += 4;
 108         year[4] = '\0';
 109         memcpy(comment, map + fpos, 30);
 110         comment[30] = '\0';
 111         unpad(title);
 112         unpad(artist);
 113         unpad(album);
 114         unpad(year);
 115         unpad(comment);
 116         return make_message("%s: %s, by %s\n" /* taginfo1 */
 117                 "%s: A: %s, Y: %s, C: %s\n", /* taginfo 2*/
 118                 status_item_list[SI_TAGINFO1],
 119                 *title? title : "(title tag not set)",
 120                 *artist? artist : "(artist tag not set)",
 121                 status_item_list[SI_TAGINFO2],
 122                 *album?  album : "(album tag not set)",
 123                 *year? year : "????",
 124                 *comment? comment : "(comment tag not set)"
 125         );
 126 }
 127
 128 static int header_frequency(struct mp3header *h)
 129 {
 130         if (h->version > 2 || h->freq > 3)
 131                 return -E_HEADER_FREQ;
 132         return frequencies[h->version][h->freq];
 133 }
 134
 135 static const char *header_mode(struct mp3header *h)
 136 {
 137         if (h->mode > 4)
 138                 h->mode = 4; /* invalid */
 139         return mode_text[h->mode];
 140 }
 141
 142 static int header_channels(struct mp3header *h)
 143 {
 144         if (h->mode > 3)
 145                 return 0;
 146         if (h->mode < 3)
 147                 return 2;
 148         return 1;
 149 }
 150
 151 static int header_bitrate(struct mp3header *h)
 152 {
 153         if (!h->layer || h->layer > 3 || h->bitrate > 14 || !h->bitrate)
 154                 return -E_HEADER_BITRATE;
 155         return mp3info_bitrate[h->version & 1][3 - h->layer][h->bitrate - 1];
 156 }
 157
 158 static int frame_length(struct mp3header *header)
 159 {
 160         int hb, hf = header_frequency(header);
 161
 162         if (hf < 0)
 163                 return hf;
 164         hb = header_bitrate(header);
 165         if (hb < 0)
 166                 return hb;
 167         if (header->sync != 0xFFE || header->layer > 3)
 168                 return -E_FRAME;
 169         return frame_size_index[3 - header->layer] *
 170                 ((header->version & 1) + 1) * hb / hf
 171                 + header->padding;
 172 }
 173
 174 static int compare_headers(struct mp3header *h1,struct mp3header *h2)
 175 {
 176         if ((*(uint*)h1) == (*(uint*)h2))
 177                 return 1;
 178         if ((h1->version == h2->version) &&
 179                         (h1->layer == h2->layer) &&
 180                         (h1->crc == h2->crc) &&
 181                         (h1->freq == h2->freq) &&
 182                         (h1->mode == h2->mode) &&
 183                         (h1->copyright == h2->copyright) &&
 184                         (h1->original == h2->original) &&
 185                         (h1->emphasis == h2->emphasis))
 186                 return 1;
 187         return 0;
 188 }
 189
 190 /*
 191  * get next MP3 frame header.
 192  *
 193  * On success, the header frame length is returned and the given header
 194  * structure that is filled in.  A return value of zero means that we did not
 195  * retrieve a valid frame header, and a negative return value indicates an
 196  * error.
 197  */
 198 static int get_header(unsigned char *map, size_t numbytes, off_t *fpos,
 199         struct mp3header *header)
 200 {
 201         int fl, ret;
 202
 203         if (*fpos + FRAME_HEADER_SIZE > numbytes) {
 204                 *fpos = numbytes - 1;
 205                 header->sync = 0;
 206                 return 0;
 207         }
 208         header->layer = (map[*fpos + 1] >> 1) & 3;
 209         header->sync = (((int)map[*fpos]<<4) | ((int)(map[*fpos + 1]&0xE0)>>4));
 210         if (map[*fpos + 1] & 0x10)
 211                 header->version = (map[*fpos + 1] >> 3) & 1;
 212         else
 213                 header->version = 2;
 214         if ((header->sync != 0xFFE) || (header->layer != 1)) {
 215                 ret = 0;
 216                 header->sync = 0;
 217                 goto out;
 218         }
 219         header->crc = map[*fpos + 1] & 1;
 220         header->bitrate = (map[*fpos + 2] >> 4) & 0x0F;
 221         header->freq = (map[*fpos + 2] >> 2) & 0x3;
 222         header->padding = (map[*fpos + 2] >>1) & 0x1;
 223         header->mode = (map[*fpos + 3] >> 6) & 0x3;
 224         fl = frame_length(header);
 225         ret = (fl >= MIN_FRAME_SIZE)? fl : -E_FRAME_LENGTH;
 226 out:
 227         *fpos += FRAME_HEADER_SIZE;
 228         return ret;
 229 }
 230
 231 /*
 232  * find the next mp3 header
 233  *
 234  * Return the length of the next frame header or zero if the end of the file is
 235  * reached.
 236  */
 237 static int mp3_seek_next_header(unsigned char *map, size_t numbytes, off_t *fpos,
 238         struct mp3header *result)
 239 {
 240         int k, l = 0, first_len;
 241         struct mp3header h, h2;
 242         long valid_start = 0;
 243
 244         for (; *fpos < numbytes; (*fpos)++) {
 245                 if (map[*fpos] != 0xff)
 246                         continue;
 247                 valid_start = *fpos;
 248                 first_len = get_header(map, numbytes, fpos, &h);
 249                 if (first_len <= 0)
 250                         continue;
 251                 *fpos += first_len - FRAME_HEADER_SIZE;
 252                 for (k = 1; k < MIN_CONSEC_GOOD_FRAMES; k++) {
 253                         if ((l = get_header(map, numbytes, fpos, &h2)) <= 0)
 254                                 break;
 255                         if (!compare_headers(&h, &h2))
 256                                 break;
 257                         *fpos += l - FRAME_HEADER_SIZE;
 258                 }
 259                 if (k == MIN_CONSEC_GOOD_FRAMES) {
 260                         *fpos = valid_start;
 261                         *result = h2;
 262                         return first_len;
 263                 }
 264         }
 265         return 0;
 266 }
 267
 268 static int find_valid_start(unsigned char *map, size_t numbytes, off_t *fpos,
 269         struct mp3header *header)
 270 {
 271         int frame_len;
 272
 273         frame_len = get_header(map, numbytes, fpos, header);
 274         if (frame_len < 0)
 275                 return frame_len;
 276         if (!frame_len) {
 277                 frame_len = mp3_seek_next_header(map, numbytes, fpos, header);
 278                 if (frame_len <= 0)
 279                         return frame_len;
 280         } else
 281                 *fpos -= FRAME_HEADER_SIZE;
 282         if (frame_len <= 1)
 283                 return -E_FRAME_LENGTH;
 284         return frame_len;
 285 }
 286
 287 static int mp3_read_info(unsigned char *map, size_t numbytes,
 288                 struct afh_info *afhi)
 289 {
 290         long freq_avg = 0, br_avg = 0;
 291         int ret, len = 0, old_br = -1, vbr = 0;
 292         struct timeval total_time = {0, 0};
 293         unsigned chunk_table_size = 1000; /* gets increased on demand */
 294         off_t fpos = 0;
 295         struct mp3header header;
 296         char *taginfo;
 297
 298         afhi->chunks_total = 0;
 299         afhi->chunk_table = para_malloc(chunk_table_size * sizeof(size_t));
 300         taginfo = mp3_get_id3(map, numbytes);
 301         while (1) {
 302                 unsigned long freq, br, fl;
 303                 struct timeval tmp, cct; /* current chunk time */
 304                 fpos += len;
 305                 len = find_valid_start(map, numbytes, &fpos, &header);
 306                 if (len <= 0)
 307                         break;
 308                 ret = header_frequency(&header);
 309                 if (ret < 0)
 310                         continue;
 311                 freq = ret;
 312                 ret = header_bitrate(&header);
 313                 if (ret < 0)
 314                         continue;
 315                 br = ret;
 316                 ret = frame_length(&header);
 317                 if (ret < 0)
 318                         continue;
 319                 fl = ret;
 320                 tmp.tv_sec = fl;
 321                 tmp.tv_usec = 0;
 322                 tv_divide(br * 125, &tmp, &cct);
 323                 tv_add(&cct, &total_time, &tmp);
 324                 total_time = tmp;
 325                 //PARA_DEBUG_LOG("%s: br: %d, freq: %d, fl: %d, cct: %lu\n", __func__, br, freq, fl, cct.tv_usec);
 326                 if (afhi->chunks_total >= chunk_table_size) {
 327                         chunk_table_size *= 2;
 328                         afhi->chunk_table = para_realloc(afhi->chunk_table,
 329                                 chunk_table_size * sizeof(size_t));
 330                 }
 331                 afhi->chunk_table[afhi->chunks_total] = fpos;
 332 //              if (afhi->chunks_total < 10 || !(afhi->chunks_total % 1000))
 333 //                      PARA_INFO_LOG("chunk #%lu: %zd\n", afhi->chunks_total,
 334 //                              afhi->chunk_table[afhi->chunks_total]);
 335                 afhi->chunks_total++;
 336                 if (afhi->chunks_total == 1) {
 337                         freq_avg = freq;
 338                         br_avg = br;
 339                         old_br = br;
 340                         continue;
 341                 }
 342                 freq_avg += ((long)freq - freq_avg) / ((long)afhi->chunks_total + 1);
 343                 br_avg += ((long)br - br_avg) / ((long)afhi->chunks_total + 1);
 344                 if (old_br != br)
 345                         vbr = 1;
 346                 old_br = br;
 347         }
 348         ret = -E_MP3_INFO;
 349         if (!afhi->chunks_total || !freq_avg || !br_avg)
 350                 goto err_out;
 351         afhi->chunk_table[afhi->chunks_total] = numbytes - 1;
 352         afhi->bitrate = br_avg;
 353         afhi->frequency = freq_avg;
 354         afhi->channels = header_channels(&header);
 355         afhi->seconds_total = (tv2ms(&total_time) + 500) / 1000;
 356         tv_divide(afhi->chunks_total, &total_time, &afhi->chunk_tv);
 357         PARA_DEBUG_LOG("%lu chunks, each %lums\n", afhi->chunks_total,
 358                 tv2ms(&afhi->chunk_tv));
 359         tv_scale(3, &afhi->chunk_tv, &afhi->eof_tv);
 360         PARA_DEBUG_LOG("eof timeout: %lu\n", tv2ms(&afhi->eof_tv));
 361         afhi->info_string = make_message("%s: %cbr, %s\n%s",
 362                 status_item_list[SI_AUDIO_FILE_INFO], vbr? 'v' : 'c',
 363                 header_mode(&header), taginfo);
 364         free(taginfo);
 365         return 1;
 366 err_out:
 367         free(taginfo);
 368         PARA_ERROR_LOG("%s\n", para_strerror(-ret));
 369         free(afhi->chunk_table);
 370         return ret;
 371 }
 372
 373 /*
 374  * Read mp3 information from audio file
 375  */
 376 int mp3_get_file_info(char *map, size_t numbytes,
 377                 struct afh_info *afhi)
 378 {
 379         int ret;
 380
 381         ret = mp3_read_info((unsigned char *)map, numbytes, afhi);
 382         if (ret < 0)
 383                 return ret;
 384         if (afhi->seconds_total < 2 || !afhi->chunks_total)
 385                 return -E_MP3_INFO;
 386         return 1;
 387 }
 388
 389 static const char* mp3_suffixes[] = {"mp3", NULL};
 390
 391 /**
 392  * the init function of the mp3 audio format handler
 393  *
 394  * \param afh pointer to the struct to initialize
 395  */
 396 void mp3_init(struct audio_format_handler *afh)
 397 {
 398         afh->get_file_info = mp3_get_file_info;
 399         afh->suffixes = mp3_suffixes;
 400 }