libavformat/ipmovie.c

   1 /*
   2  * Interplay MVE File Demuxer
   3  * Copyright (c) 2003 The ffmpeg Project
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file libavformat/ipmovie.c
  24  * Interplay MVE file demuxer
  25  * by Mike Melanson (melanson@pcisys.net)
  26  * For more information regarding the Interplay MVE file format, visit:
  27  *   http://www.pcisys.net/~melanson/codecs/
  28  * The aforementioned site also contains a command line utility for parsing
  29  * IP MVE files so that you can get a good idea of the typical structure of
  30  * such files. This demuxer is not the best example to use if you are trying
  31  * to write your own as it uses a rather roundabout approach for splitting
  32  * up and sending out the chunks.
  33  */
  34
  35 #include "libavutil/intreadwrite.h"
  36 #include "avformat.h"
  37
  38 /* debugging support: #define DEBUG_IPMOVIE as non-zero to see extremely
  39  * verbose information about the demux process */
  40 #define DEBUG_IPMOVIE 0
  41
  42 #if DEBUG_IPMOVIE
  43 #undef printf
  44 #define debug_ipmovie printf
  45 #else
  46 static inline void debug_ipmovie(const char *format, ...) { }
  47 #endif
  48
  49 #define CHUNK_PREAMBLE_SIZE 4
  50 #define OPCODE_PREAMBLE_SIZE 4
  51
  52 #define CHUNK_INIT_AUDIO   0x0000
  53 #define CHUNK_AUDIO_ONLY   0x0001
  54 #define CHUNK_INIT_VIDEO   0x0002
  55 #define CHUNK_VIDEO        0x0003
  56 #define CHUNK_SHUTDOWN     0x0004
  57 #define CHUNK_END          0x0005
  58 /* these last types are used internally */
  59 #define CHUNK_DONE         0xFFFC
  60 #define CHUNK_NOMEM        0xFFFD
  61 #define CHUNK_EOF          0xFFFE
  62 #define CHUNK_BAD          0xFFFF
  63
  64 #define OPCODE_END_OF_STREAM           0x00
  65 #define OPCODE_END_OF_CHUNK            0x01
  66 #define OPCODE_CREATE_TIMER            0x02
  67 #define OPCODE_INIT_AUDIO_BUFFERS      0x03
  68 #define OPCODE_START_STOP_AUDIO        0x04
  69 #define OPCODE_INIT_VIDEO_BUFFERS      0x05
  70 #define OPCODE_UNKNOWN_06              0x06
  71 #define OPCODE_SEND_BUFFER             0x07
  72 #define OPCODE_AUDIO_FRAME             0x08
  73 #define OPCODE_SILENCE_FRAME           0x09
  74 #define OPCODE_INIT_VIDEO_MODE         0x0A
  75 #define OPCODE_CREATE_GRADIENT         0x0B
  76 #define OPCODE_SET_PALETTE             0x0C
  77 #define OPCODE_SET_PALETTE_COMPRESSED  0x0D
  78 #define OPCODE_UNKNOWN_0E              0x0E
  79 #define OPCODE_SET_DECODING_MAP        0x0F
  80 #define OPCODE_UNKNOWN_10              0x10
  81 #define OPCODE_VIDEO_DATA              0x11
  82 #define OPCODE_UNKNOWN_12              0x12
  83 #define OPCODE_UNKNOWN_13              0x13
  84 #define OPCODE_UNKNOWN_14              0x14
  85 #define OPCODE_UNKNOWN_15              0x15
  86
  87 #define PALETTE_COUNT 256
  88
  89 typedef struct IPMVEContext {
  90
  91     unsigned char *buf;
  92     int buf_size;
  93
  94     uint64_t frame_pts_inc;
  95
  96     unsigned int video_width;
  97     unsigned int video_height;
  98     int64_t video_pts;
  99
 100     unsigned int audio_bits;
 101     unsigned int audio_channels;
 102     unsigned int audio_sample_rate;
 103     enum CodecID audio_type;
 104     unsigned int audio_frame_count;
 105
 106     int video_stream_index;
 107     int audio_stream_index;
 108
 109     int64_t audio_chunk_offset;
 110     int audio_chunk_size;
 111     int64_t video_chunk_offset;
 112     int video_chunk_size;
 113     int64_t decode_map_chunk_offset;
 114     int decode_map_chunk_size;
 115
 116     int64_t next_chunk_offset;
 117
 118     AVPaletteControl palette_control;
 119
 120 } IPMVEContext;
 121
 122 static int load_ipmovie_packet(IPMVEContext *s, ByteIOContext *pb,
 123     AVPacket *pkt) {
 124
 125     int chunk_type;
 126
 127     if (s->audio_chunk_offset) {
 128
 129         /* adjust for PCM audio by skipping chunk header */
 130         if (s->audio_type != CODEC_ID_INTERPLAY_DPCM) {
 131             s->audio_chunk_offset += 6;
 132             s->audio_chunk_size -= 6;
 133         }
 134
 135         url_fseek(pb, s->audio_chunk_offset, SEEK_SET);
 136         s->audio_chunk_offset = 0;
 137
 138         if (s->audio_chunk_size != av_get_packet(pb, pkt, s->audio_chunk_size))
 139             return CHUNK_EOF;
 140
 141         pkt->stream_index = s->audio_stream_index;
 142         pkt->pts = s->audio_frame_count;
 143
 144         /* audio frame maintenance */
 145         if (s->audio_type != CODEC_ID_INTERPLAY_DPCM)
 146             s->audio_frame_count +=
 147             (s->audio_chunk_size / s->audio_channels / (s->audio_bits / 8));
 148         else
 149             s->audio_frame_count +=
 150                 (s->audio_chunk_size - 6) / s->audio_channels;
 151
 152         debug_ipmovie("sending audio frame with pts %"PRId64" (%d audio frames)\n",
 153             pkt->pts, s->audio_frame_count);
 154
 155         chunk_type = CHUNK_VIDEO;
 156
 157     } else if (s->decode_map_chunk_offset) {
 158
 159         /* send both the decode map and the video data together */
 160
 161         if (av_new_packet(pkt, s->decode_map_chunk_size + s->video_chunk_size))
 162             return CHUNK_NOMEM;
 163
 164         pkt->pos= s->decode_map_chunk_offset;
 165         url_fseek(pb, s->decode_map_chunk_offset, SEEK_SET);
 166         s->decode_map_chunk_offset = 0;
 167
 168         if (get_buffer(pb, pkt->data, s->decode_map_chunk_size) !=
 169             s->decode_map_chunk_size) {
 170             av_free_packet(pkt);
 171             return CHUNK_EOF;
 172         }
 173
 174         url_fseek(pb, s->video_chunk_offset, SEEK_SET);
 175         s->video_chunk_offset = 0;
 176
 177         if (get_buffer(pb, pkt->data + s->decode_map_chunk_size,
 178             s->video_chunk_size) != s->video_chunk_size) {
 179             av_free_packet(pkt);
 180             return CHUNK_EOF;
 181         }
 182
 183         pkt->stream_index = s->video_stream_index;
 184         pkt->pts = s->video_pts;
 185
 186         debug_ipmovie("sending video frame with pts %"PRId64"\n",
 187             pkt->pts);
 188
 189         s->video_pts += s->frame_pts_inc;
 190
 191         chunk_type = CHUNK_VIDEO;
 192
 193     } else {
 194
 195         url_fseek(pb, s->next_chunk_offset, SEEK_SET);
 196         chunk_type = CHUNK_DONE;
 197
 198     }
 199
 200     return chunk_type;
 201 }
 202
 203 /* This function loads and processes a single chunk in an IP movie file.
 204  * It returns the type of chunk that was processed. */
 205 static int process_ipmovie_chunk(IPMVEContext *s, ByteIOContext *pb,
 206     AVPacket *pkt)
 207 {
 208     unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
 209     int chunk_type;
 210     int chunk_size;
 211     unsigned char opcode_preamble[OPCODE_PREAMBLE_SIZE];
 212     unsigned char opcode_type;
 213     unsigned char opcode_version;
 214     int opcode_size;
 215     unsigned char scratch[1024];
 216     int i, j;
 217     int first_color, last_color;
 218     int audio_flags;
 219     unsigned char r, g, b;
 220
 221     /* see if there are any pending packets */
 222     chunk_type = load_ipmovie_packet(s, pb, pkt);
 223     if (chunk_type != CHUNK_DONE)
 224         return chunk_type;
 225
 226     /* read the next chunk, wherever the file happens to be pointing */
 227     if (url_feof(pb))
 228         return CHUNK_EOF;
 229     if (get_buffer(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
 230         CHUNK_PREAMBLE_SIZE)
 231         return CHUNK_BAD;
 232     chunk_size = AV_RL16(&chunk_preamble[0]);
 233     chunk_type = AV_RL16(&chunk_preamble[2]);
 234
 235     debug_ipmovie("chunk type 0x%04X, 0x%04X bytes: ", chunk_type, chunk_size);
 236
 237     switch (chunk_type) {
 238
 239     case CHUNK_INIT_AUDIO:
 240         debug_ipmovie("initialize audio\n");
 241         break;
 242
 243     case CHUNK_AUDIO_ONLY:
 244         debug_ipmovie("audio only\n");
 245         break;
 246
 247     case CHUNK_INIT_VIDEO:
 248         debug_ipmovie("initialize video\n");
 249         break;
 250
 251     case CHUNK_VIDEO:
 252         debug_ipmovie("video (and audio)\n");
 253         break;
 254
 255     case CHUNK_SHUTDOWN:
 256         debug_ipmovie("shutdown\n");
 257         break;
 258
 259     case CHUNK_END:
 260         debug_ipmovie("end\n");
 261         break;
 262
 263     default:
 264         debug_ipmovie("invalid chunk\n");
 265         chunk_type = CHUNK_BAD;
 266         break;
 267
 268     }
 269
 270     while ((chunk_size > 0) && (chunk_type != CHUNK_BAD)) {
 271
 272         /* read the next chunk, wherever the file happens to be pointing */
 273        if (url_feof(pb)) {
 274             chunk_type = CHUNK_EOF;
 275             break;
 276         }
 277         if (get_buffer(pb, opcode_preamble, CHUNK_PREAMBLE_SIZE) !=
 278             CHUNK_PREAMBLE_SIZE) {
 279             chunk_type = CHUNK_BAD;
 280             break;
 281         }
 282
 283         opcode_size = AV_RL16(&opcode_preamble[0]);
 284         opcode_type = opcode_preamble[2];
 285         opcode_version = opcode_preamble[3];
 286
 287         chunk_size -= OPCODE_PREAMBLE_SIZE;
 288         chunk_size -= opcode_size;
 289         if (chunk_size < 0) {
 290             debug_ipmovie("chunk_size countdown just went negative\n");
 291             chunk_type = CHUNK_BAD;
 292             break;
 293         }
 294
 295         debug_ipmovie("  opcode type %02X, version %d, 0x%04X bytes: ",
 296             opcode_type, opcode_version, opcode_size);
 297         switch (opcode_type) {
 298
 299         case OPCODE_END_OF_STREAM:
 300             debug_ipmovie("end of stream\n");
 301             url_fseek(pb, opcode_size, SEEK_CUR);
 302             break;
 303
 304         case OPCODE_END_OF_CHUNK:
 305             debug_ipmovie("end of chunk\n");
 306             url_fseek(pb, opcode_size, SEEK_CUR);
 307             break;
 308
 309         case OPCODE_CREATE_TIMER:
 310             debug_ipmovie("create timer\n");
 311             if ((opcode_version > 0) || (opcode_size > 6)) {
 312                 debug_ipmovie("bad create_timer opcode\n");
 313                 chunk_type = CHUNK_BAD;
 314                 break;
 315             }
 316             if (get_buffer(pb, scratch, opcode_size) !=
 317                 opcode_size) {
 318                 chunk_type = CHUNK_BAD;
 319                 break;
 320             }
 321             s->frame_pts_inc = ((uint64_t)AV_RL32(&scratch[0])) * AV_RL16(&scratch[4]);
 322             debug_ipmovie("  %.2f frames/second (timer div = %d, subdiv = %d)\n",
 323                 1000000.0/s->frame_pts_inc, AV_RL32(&scratch[0]), AV_RL16(&scratch[4]));
 324             break;
 325
 326         case OPCODE_INIT_AUDIO_BUFFERS:
 327             debug_ipmovie("initialize audio buffers\n");
 328             if ((opcode_version > 1) || (opcode_size > 10)) {
 329                 debug_ipmovie("bad init_audio_buffers opcode\n");
 330                 chunk_type = CHUNK_BAD;
 331                 break;
 332             }
 333             if (get_buffer(pb, scratch, opcode_size) !=
 334                 opcode_size) {
 335                 chunk_type = CHUNK_BAD;
 336                 break;
 337             }
 338             s->audio_sample_rate = AV_RL16(&scratch[4]);
 339             audio_flags = AV_RL16(&scratch[2]);
 340             /* bit 0 of the flags: 0 = mono, 1 = stereo */
 341             s->audio_channels = (audio_flags & 1) + 1;
 342             /* bit 1 of the flags: 0 = 8 bit, 1 = 16 bit */
 343             s->audio_bits = (((audio_flags >> 1) & 1) + 1) * 8;
 344             /* bit 2 indicates compressed audio in version 1 opcode */
 345             if ((opcode_version == 1) && (audio_flags & 0x4))
 346                 s->audio_type = CODEC_ID_INTERPLAY_DPCM;
 347             else if (s->audio_bits == 16)
 348                 s->audio_type = CODEC_ID_PCM_S16LE;
 349             else
 350                 s->audio_type = CODEC_ID_PCM_U8;
 351             debug_ipmovie("audio: %d bits, %d Hz, %s, %s format\n",
 352                 s->audio_bits,
 353                 s->audio_sample_rate,
 354                 (s->audio_channels == 2) ? "stereo" : "mono",
 355                 (s->audio_type == CODEC_ID_INTERPLAY_DPCM) ?
 356                 "Interplay audio" : "PCM");
 357             break;
 358
 359         case OPCODE_START_STOP_AUDIO:
 360             debug_ipmovie("start/stop audio\n");
 361             url_fseek(pb, opcode_size, SEEK_CUR);
 362             break;
 363
 364         case OPCODE_INIT_VIDEO_BUFFERS:
 365             debug_ipmovie("initialize video buffers\n");
 366             if ((opcode_version > 2) || (opcode_size > 8)) {
 367                 debug_ipmovie("bad init_video_buffers opcode\n");
 368                 chunk_type = CHUNK_BAD;
 369                 break;
 370             }
 371             if (get_buffer(pb, scratch, opcode_size) !=
 372                 opcode_size) {
 373                 chunk_type = CHUNK_BAD;
 374                 break;
 375             }
 376             s->video_width = AV_RL16(&scratch[0]) * 8;
 377             s->video_height = AV_RL16(&scratch[2]) * 8;
 378             debug_ipmovie("video resolution: %d x %d\n",
 379                 s->video_width, s->video_height);
 380             break;
 381
 382         case OPCODE_UNKNOWN_06:
 383         case OPCODE_UNKNOWN_0E:
 384         case OPCODE_UNKNOWN_10:
 385         case OPCODE_UNKNOWN_12:
 386         case OPCODE_UNKNOWN_13:
 387         case OPCODE_UNKNOWN_14:
 388         case OPCODE_UNKNOWN_15:
 389             debug_ipmovie("unknown (but documented) opcode %02X\n", opcode_type);
 390             url_fseek(pb, opcode_size, SEEK_CUR);
 391             break;
 392
 393         case OPCODE_SEND_BUFFER:
 394             debug_ipmovie("send buffer\n");
 395             url_fseek(pb, opcode_size, SEEK_CUR);
 396             break;
 397
 398         case OPCODE_AUDIO_FRAME:
 399             debug_ipmovie("audio frame\n");
 400
 401             /* log position and move on for now */
 402             s->audio_chunk_offset = url_ftell(pb);
 403             s->audio_chunk_size = opcode_size;
 404             url_fseek(pb, opcode_size, SEEK_CUR);
 405             break;
 406
 407         case OPCODE_SILENCE_FRAME:
 408             debug_ipmovie("silence frame\n");
 409             url_fseek(pb, opcode_size, SEEK_CUR);
 410             break;
 411
 412         case OPCODE_INIT_VIDEO_MODE:
 413             debug_ipmovie("initialize video mode\n");
 414             url_fseek(pb, opcode_size, SEEK_CUR);
 415             break;
 416
 417         case OPCODE_CREATE_GRADIENT:
 418             debug_ipmovie("create gradient\n");
 419             url_fseek(pb, opcode_size, SEEK_CUR);
 420             break;
 421
 422         case OPCODE_SET_PALETTE:
 423             debug_ipmovie("set palette\n");
 424             /* check for the logical maximum palette size
 425              * (3 * 256 + 4 bytes) */
 426             if (opcode_size > 0x304) {
 427                 debug_ipmovie("demux_ipmovie: set_palette opcode too large\n");
 428                 chunk_type = CHUNK_BAD;
 429                 break;
 430             }
 431             if (get_buffer(pb, scratch, opcode_size) != opcode_size) {
 432                 chunk_type = CHUNK_BAD;
 433                 break;
 434             }
 435
 436             /* load the palette into internal data structure */
 437             first_color = AV_RL16(&scratch[0]);
 438             last_color = first_color + AV_RL16(&scratch[2]) - 1;
 439             /* sanity check (since they are 16 bit values) */
 440             if ((first_color > 0xFF) || (last_color > 0xFF)) {
 441                 debug_ipmovie("demux_ipmovie: set_palette indexes out of range (%d -> %d)\n",
 442                     first_color, last_color);
 443                 chunk_type = CHUNK_BAD;
 444                 break;
 445             }
 446             j = 4;  /* offset of first palette data */
 447             for (i = first_color; i <= last_color; i++) {
 448                 /* the palette is stored as a 6-bit VGA palette, thus each
 449                  * component is shifted up to a 8-bit range */
 450                 r = scratch[j++] * 4;
 451                 g = scratch[j++] * 4;
 452                 b = scratch[j++] * 4;
 453                 s->palette_control.palette[i] = (r << 16) | (g << 8) | (b);
 454             }
 455             /* indicate a palette change */
 456             s->palette_control.palette_changed = 1;
 457             break;
 458
 459         case OPCODE_SET_PALETTE_COMPRESSED:
 460             debug_ipmovie("set palette compressed\n");
 461             url_fseek(pb, opcode_size, SEEK_CUR);
 462             break;
 463
 464         case OPCODE_SET_DECODING_MAP:
 465             debug_ipmovie("set decoding map\n");
 466
 467             /* log position and move on for now */
 468             s->decode_map_chunk_offset = url_ftell(pb);
 469             s->decode_map_chunk_size = opcode_size;
 470             url_fseek(pb, opcode_size, SEEK_CUR);
 471             break;
 472
 473         case OPCODE_VIDEO_DATA:
 474             debug_ipmovie("set video data\n");
 475
 476             /* log position and move on for now */
 477             s->video_chunk_offset = url_ftell(pb);
 478             s->video_chunk_size = opcode_size;
 479             url_fseek(pb, opcode_size, SEEK_CUR);
 480             break;
 481
 482         default:
 483             debug_ipmovie("*** unknown opcode type\n");
 484             chunk_type = CHUNK_BAD;
 485             break;
 486
 487         }
 488     }
 489
 490     /* make a note of where the stream is sitting */
 491     s->next_chunk_offset = url_ftell(pb);
 492
 493     /* dispatch the first of any pending packets */
 494     if ((chunk_type == CHUNK_VIDEO) || (chunk_type == CHUNK_AUDIO_ONLY))
 495         chunk_type = load_ipmovie_packet(s, pb, pkt);
 496
 497     return chunk_type;
 498 }
 499
 500 static const char signature[] = "Interplay MVE File\x1A\0\x1A";
 501
 502 static int ipmovie_probe(AVProbeData *p)
 503 {
 504     uint8_t *b = p->buf;
 505     uint8_t *b_end = p->buf + p->buf_size - sizeof(signature);
 506     do {
 507         if (memcmp(b++, signature, sizeof(signature)) == 0)
 508             return AVPROBE_SCORE_MAX;
 509     } while (b < b_end);
 510
 511     return 0;
 512 }
 513
 514 static int ipmovie_read_header(AVFormatContext *s,
 515                                AVFormatParameters *ap)
 516 {
 517     IPMVEContext *ipmovie = s->priv_data;
 518     ByteIOContext *pb = s->pb;
 519     AVPacket pkt;
 520     AVStream *st;
 521     unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
 522     int chunk_type;
 523     uint8_t signature_buffer[sizeof(signature)];
 524
 525     get_buffer(pb, signature_buffer, sizeof(signature_buffer));
 526     while (memcmp(signature_buffer, signature, sizeof(signature))) {
 527         memmove(signature_buffer, signature_buffer + 1, sizeof(signature_buffer) - 1);
 528         signature_buffer[sizeof(signature_buffer) - 1] = get_byte(pb);
 529         if (url_feof(pb))
 530             return AVERROR_EOF;
 531     }
 532     /* initialize private context members */
 533     ipmovie->video_pts = ipmovie->audio_frame_count = 0;
 534     ipmovie->audio_chunk_offset = ipmovie->video_chunk_offset =
 535     ipmovie->decode_map_chunk_offset = 0;
 536
 537     /* on the first read, this will position the stream at the first chunk */
 538     ipmovie->next_chunk_offset = url_ftell(pb) + 4;
 539
 540     /* process the first chunk which should be CHUNK_INIT_VIDEO */
 541     if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_VIDEO)
 542         return AVERROR_INVALIDDATA;
 543
 544     /* peek ahead to the next chunk-- if it is an init audio chunk, process
 545      * it; if it is the first video chunk, this is a silent file */
 546     if (get_buffer(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
 547         CHUNK_PREAMBLE_SIZE)
 548         return AVERROR(EIO);
 549     chunk_type = AV_RL16(&chunk_preamble[2]);
 550     url_fseek(pb, -CHUNK_PREAMBLE_SIZE, SEEK_CUR);
 551
 552     if (chunk_type == CHUNK_VIDEO)
 553         ipmovie->audio_type = CODEC_ID_NONE;  /* no audio */
 554     else if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_AUDIO)
 555         return AVERROR_INVALIDDATA;
 556
 557     /* initialize the stream decoders */
 558     st = av_new_stream(s, 0);
 559     if (!st)
 560         return AVERROR(ENOMEM);
 561     av_set_pts_info(st, 63, 1, 1000000);
 562     ipmovie->video_stream_index = st->index;
 563     st->codec->codec_type = CODEC_TYPE_VIDEO;
 564     st->codec->codec_id = CODEC_ID_INTERPLAY_VIDEO;
 565     st->codec->codec_tag = 0;  /* no fourcc */
 566     st->codec->width = ipmovie->video_width;
 567     st->codec->height = ipmovie->video_height;
 568
 569     /* palette considerations */
 570     st->codec->palctrl = &ipmovie->palette_control;
 571
 572     if (ipmovie->audio_type) {
 573         st = av_new_stream(s, 0);
 574         if (!st)
 575             return AVERROR(ENOMEM);
 576         av_set_pts_info(st, 32, 1, ipmovie->audio_sample_rate);
 577         ipmovie->audio_stream_index = st->index;
 578         st->codec->codec_type = CODEC_TYPE_AUDIO;
 579         st->codec->codec_id = ipmovie->audio_type;
 580         st->codec->codec_tag = 0;  /* no tag */
 581         st->codec->channels = ipmovie->audio_channels;
 582         st->codec->sample_rate = ipmovie->audio_sample_rate;
 583         st->codec->bits_per_coded_sample = ipmovie->audio_bits;
 584         st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
 585             st->codec->bits_per_coded_sample;
 586         if (st->codec->codec_id == CODEC_ID_INTERPLAY_DPCM)
 587             st->codec->bit_rate /= 2;
 588         st->codec->block_align = st->codec->channels * st->codec->bits_per_coded_sample;
 589     }
 590
 591     return 0;
 592 }
 593
 594 static int ipmovie_read_packet(AVFormatContext *s,
 595                                AVPacket *pkt)
 596 {
 597     IPMVEContext *ipmovie = s->priv_data;
 598     ByteIOContext *pb = s->pb;
 599     int ret;
 600
 601     ret = process_ipmovie_chunk(ipmovie, pb, pkt);
 602     if (ret == CHUNK_BAD)
 603         ret = AVERROR_INVALIDDATA;
 604     else if (ret == CHUNK_EOF)
 605         ret = AVERROR(EIO);
 606     else if (ret == CHUNK_NOMEM)
 607         ret = AVERROR(ENOMEM);
 608     else if (ret == CHUNK_VIDEO)
 609         ret = 0;
 610     else
 611         ret = -1;
 612
 613     return ret;
 614 }
 615
 616 AVInputFormat ipmovie_demuxer = {
 617     "ipmovie",
 618     NULL_IF_CONFIG_SMALL("Interplay MVE format"),
 619     sizeof(IPMVEContext),
 620     ipmovie_probe,
 621     ipmovie_read_header,
 622     ipmovie_read_packet,
 623 };