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 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 "avformat.h"
  36
  37 /* debugging support: #define DEBUG_IPMOVIE as non-zero to see extremely
  38  * verbose information about the demux process */
  39 #define DEBUG_IPMOVIE 0
  40
  41 #if DEBUG_IPMOVIE
  42 #define debug_ipmovie printf
  43 #else
  44 static inline void debug_ipmovie(const char *format, ...) { }
  45 #endif
  46
  47 #define IPMOVIE_SIGNATURE "Interplay MVE File\x1A\0"
  48 #define IPMOVIE_SIGNATURE_SIZE 20
  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     float fps;
  95     int frame_pts_inc;
  96
  97     unsigned int video_width;
  98     unsigned int video_height;
  99     int64_t video_pts;
 100
 101     unsigned int audio_bits;
 102     unsigned int audio_channels;
 103     unsigned int audio_sample_rate;
 104     unsigned int audio_type;
 105     unsigned int audio_frame_count;
 106
 107     int video_stream_index;
 108     int audio_stream_index;
 109
 110     offset_t audio_chunk_offset;
 111     int audio_chunk_size;
 112     offset_t video_chunk_offset;
 113     int video_chunk_size;
 114     offset_t decode_map_chunk_offset;
 115     int decode_map_chunk_size;
 116
 117     offset_t next_chunk_offset;
 118
 119     AVPaletteControl palette_control;
 120
 121 } IPMVEContext;
 122
 123 static int load_ipmovie_packet(IPMVEContext *s, ByteIOContext *pb,
 124     AVPacket *pkt) {
 125
 126     int chunk_type;
 127     int64_t audio_pts = 0;
 128
 129     if (s->audio_chunk_offset) {
 130
 131         /* adjust for PCM audio by skipping chunk header */
 132         if (s->audio_type != CODEC_ID_INTERPLAY_DPCM) {
 133             s->audio_chunk_offset += 6;
 134             s->audio_chunk_size -= 6;
 135         }
 136
 137         url_fseek(pb, s->audio_chunk_offset, SEEK_SET);
 138         s->audio_chunk_offset = 0;
 139
 140         /* figure out the audio pts */
 141         audio_pts = 90000;
 142         audio_pts *= s->audio_frame_count;
 143         audio_pts /= s->audio_sample_rate;
 144
 145         if (s->audio_chunk_size != av_get_packet(pb, pkt, s->audio_chunk_size))
 146             return CHUNK_EOF;
 147
 148         pkt->stream_index = s->audio_stream_index;
 149         pkt->pts = audio_pts;
 150
 151         /* audio frame maintenance */
 152         if (s->audio_type != CODEC_ID_INTERPLAY_DPCM)
 153             s->audio_frame_count +=
 154             (s->audio_chunk_size / s->audio_channels / (s->audio_bits / 8));
 155         else
 156             s->audio_frame_count +=
 157                 (s->audio_chunk_size - 6) / s->audio_channels;
 158
 159         debug_ipmovie("sending audio frame with pts %"PRId64" (%d audio frames)\n",
 160             audio_pts, s->audio_frame_count);
 161
 162         chunk_type = CHUNK_VIDEO;
 163
 164     } else if (s->decode_map_chunk_offset) {
 165
 166         /* send both the decode map and the video data together */
 167
 168         if (av_new_packet(pkt, s->decode_map_chunk_size + s->video_chunk_size))
 169             return CHUNK_NOMEM;
 170
 171         pkt->pos= s->decode_map_chunk_offset;
 172         url_fseek(pb, s->decode_map_chunk_offset, SEEK_SET);
 173         s->decode_map_chunk_offset = 0;
 174
 175         if (get_buffer(pb, pkt->data, s->decode_map_chunk_size) !=
 176             s->decode_map_chunk_size) {
 177             av_free_packet(pkt);
 178             return CHUNK_EOF;
 179         }
 180
 181         url_fseek(pb, s->video_chunk_offset, SEEK_SET);
 182         s->video_chunk_offset = 0;
 183
 184         if (get_buffer(pb, pkt->data + s->decode_map_chunk_size,
 185             s->video_chunk_size) != s->video_chunk_size) {
 186             av_free_packet(pkt);
 187             return CHUNK_EOF;
 188         }
 189
 190         pkt->stream_index = s->video_stream_index;
 191         pkt->pts = s->video_pts;
 192
 193         debug_ipmovie("sending video frame with pts %"PRId64"\n",
 194             pkt->pts);
 195
 196         s->video_pts += s->frame_pts_inc;
 197
 198         chunk_type = CHUNK_VIDEO;
 199
 200     } else {
 201
 202         url_fseek(pb, s->next_chunk_offset, SEEK_SET);
 203         chunk_type = CHUNK_DONE;
 204
 205     }
 206
 207     return chunk_type;
 208 }
 209
 210 /* This function loads and processes a single chunk in an IP movie file.
 211  * It returns the type of chunk that was processed. */
 212 static int process_ipmovie_chunk(IPMVEContext *s, ByteIOContext *pb,
 213     AVPacket *pkt)
 214 {
 215     unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
 216     int chunk_type;
 217     int chunk_size;
 218     unsigned char opcode_preamble[OPCODE_PREAMBLE_SIZE];
 219     unsigned char opcode_type;
 220     unsigned char opcode_version;
 221     int opcode_size;
 222     unsigned char scratch[1024];
 223     int i, j;
 224     int first_color, last_color;
 225     int audio_flags;
 226     unsigned char r, g, b;
 227
 228     /* see if there are any pending packets */
 229     chunk_type = load_ipmovie_packet(s, pb, pkt);
 230     if (chunk_type != CHUNK_DONE)
 231         return chunk_type;
 232
 233     /* read the next chunk, wherever the file happens to be pointing */
 234     if (url_feof(pb))
 235         return CHUNK_EOF;
 236     if (get_buffer(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
 237         CHUNK_PREAMBLE_SIZE)
 238         return CHUNK_BAD;
 239     chunk_size = AV_RL16(&chunk_preamble[0]);
 240     chunk_type = AV_RL16(&chunk_preamble[2]);
 241
 242     debug_ipmovie("chunk type 0x%04X, 0x%04X bytes: ", chunk_type, chunk_size);
 243
 244     switch (chunk_type) {
 245
 246     case CHUNK_INIT_AUDIO:
 247         debug_ipmovie("initialize audio\n");
 248         break;
 249
 250     case CHUNK_AUDIO_ONLY:
 251         debug_ipmovie("audio only\n");
 252         break;
 253
 254     case CHUNK_INIT_VIDEO:
 255         debug_ipmovie("initialize video\n");
 256         break;
 257
 258     case CHUNK_VIDEO:
 259         debug_ipmovie("video (and audio)\n");
 260         break;
 261
 262     case CHUNK_SHUTDOWN:
 263         debug_ipmovie("shutdown\n");
 264         break;
 265
 266     case CHUNK_END:
 267         debug_ipmovie("end\n");
 268         break;
 269
 270     default:
 271         debug_ipmovie("invalid chunk\n");
 272         chunk_type = CHUNK_BAD;
 273         break;
 274
 275     }
 276
 277     while ((chunk_size > 0) && (chunk_type != CHUNK_BAD)) {
 278
 279         /* read the next chunk, wherever the file happens to be pointing */
 280        if (url_feof(pb)) {
 281             chunk_type = CHUNK_EOF;
 282             break;
 283         }
 284         if (get_buffer(pb, opcode_preamble, CHUNK_PREAMBLE_SIZE) !=
 285             CHUNK_PREAMBLE_SIZE) {
 286             chunk_type = CHUNK_BAD;
 287             break;
 288         }
 289
 290         opcode_size = AV_RL16(&opcode_preamble[0]);
 291         opcode_type = opcode_preamble[2];
 292         opcode_version = opcode_preamble[3];
 293
 294         chunk_size -= OPCODE_PREAMBLE_SIZE;
 295         chunk_size -= opcode_size;
 296         if (chunk_size < 0) {
 297             debug_ipmovie("chunk_size countdown just went negative\n");
 298             chunk_type = CHUNK_BAD;
 299             break;
 300         }
 301
 302         debug_ipmovie("  opcode type %02X, version %d, 0x%04X bytes: ",
 303             opcode_type, opcode_version, opcode_size);
 304         switch (opcode_type) {
 305
 306         case OPCODE_END_OF_STREAM:
 307             debug_ipmovie("end of stream\n");
 308             url_fseek(pb, opcode_size, SEEK_CUR);
 309             break;
 310
 311         case OPCODE_END_OF_CHUNK:
 312             debug_ipmovie("end of chunk\n");
 313             url_fseek(pb, opcode_size, SEEK_CUR);
 314             break;
 315
 316         case OPCODE_CREATE_TIMER:
 317             debug_ipmovie("create timer\n");
 318             if ((opcode_version > 0) || (opcode_size > 6)) {
 319                 debug_ipmovie("bad create_timer opcode\n");
 320                 chunk_type = CHUNK_BAD;
 321                 break;
 322             }
 323             if (get_buffer(pb, scratch, opcode_size) !=
 324                 opcode_size) {
 325                 chunk_type = CHUNK_BAD;
 326                 break;
 327             }
 328             s->fps = 1000000.0 / (AV_RL32(&scratch[0]) * AV_RL16(&scratch[4]));
 329             s->frame_pts_inc = 90000 / s->fps;
 330             debug_ipmovie("  %.2f frames/second (timer div = %d, subdiv = %d)\n",
 331                 s->fps, AV_RL32(&scratch[0]), AV_RL16(&scratch[4]));
 332             break;
 333
 334         case OPCODE_INIT_AUDIO_BUFFERS:
 335             debug_ipmovie("initialize audio buffers\n");
 336             if ((opcode_version > 1) || (opcode_size > 10)) {
 337                 debug_ipmovie("bad init_audio_buffers opcode\n");
 338                 chunk_type = CHUNK_BAD;
 339                 break;
 340             }
 341             if (get_buffer(pb, scratch, opcode_size) !=
 342                 opcode_size) {
 343                 chunk_type = CHUNK_BAD;
 344                 break;
 345             }
 346             s->audio_sample_rate = AV_RL16(&scratch[4]);
 347             audio_flags = AV_RL16(&scratch[2]);
 348             /* bit 0 of the flags: 0 = mono, 1 = stereo */
 349             s->audio_channels = (audio_flags & 1) + 1;
 350             /* bit 1 of the flags: 0 = 8 bit, 1 = 16 bit */
 351             s->audio_bits = (((audio_flags >> 1) & 1) + 1) * 8;
 352             /* bit 2 indicates compressed audio in version 1 opcode */
 353             if ((opcode_version == 1) && (audio_flags & 0x4))
 354                 s->audio_type = CODEC_ID_INTERPLAY_DPCM;
 355             else if (s->audio_bits == 16)
 356                 s->audio_type = CODEC_ID_PCM_S16LE;
 357             else
 358                 s->audio_type = CODEC_ID_PCM_U8;
 359             debug_ipmovie("audio: %d bits, %d Hz, %s, %s format\n",
 360                 s->audio_bits,
 361                 s->audio_sample_rate,
 362                 (s->audio_channels == 2) ? "stereo" : "mono",
 363                 (s->audio_type == CODEC_ID_INTERPLAY_DPCM) ?
 364                 "Interplay audio" : "PCM");
 365             break;
 366
 367         case OPCODE_START_STOP_AUDIO:
 368             debug_ipmovie("start/stop audio\n");
 369             url_fseek(pb, opcode_size, SEEK_CUR);
 370             break;
 371
 372         case OPCODE_INIT_VIDEO_BUFFERS:
 373             debug_ipmovie("initialize video buffers\n");
 374             if ((opcode_version > 2) || (opcode_size > 8)) {
 375                 debug_ipmovie("bad init_video_buffers opcode\n");
 376                 chunk_type = CHUNK_BAD;
 377                 break;
 378             }
 379             if (get_buffer(pb, scratch, opcode_size) !=
 380                 opcode_size) {
 381                 chunk_type = CHUNK_BAD;
 382                 break;
 383             }
 384             s->video_width = AV_RL16(&scratch[0]) * 8;
 385             s->video_height = AV_RL16(&scratch[2]) * 8;
 386             debug_ipmovie("video resolution: %d x %d\n",
 387                 s->video_width, s->video_height);
 388             break;
 389
 390         case OPCODE_UNKNOWN_06:
 391         case OPCODE_UNKNOWN_0E:
 392         case OPCODE_UNKNOWN_10:
 393         case OPCODE_UNKNOWN_12:
 394         case OPCODE_UNKNOWN_13:
 395         case OPCODE_UNKNOWN_14:
 396         case OPCODE_UNKNOWN_15:
 397             debug_ipmovie("unknown (but documented) opcode %02X\n", opcode_type);
 398             url_fseek(pb, opcode_size, SEEK_CUR);
 399             break;
 400
 401         case OPCODE_SEND_BUFFER:
 402             debug_ipmovie("send buffer\n");
 403             url_fseek(pb, opcode_size, SEEK_CUR);
 404             break;
 405
 406         case OPCODE_AUDIO_FRAME:
 407             debug_ipmovie("audio frame\n");
 408
 409             /* log position and move on for now */
 410             s->audio_chunk_offset = url_ftell(pb);
 411             s->audio_chunk_size = opcode_size;
 412             url_fseek(pb, opcode_size, SEEK_CUR);
 413             break;
 414
 415         case OPCODE_SILENCE_FRAME:
 416             debug_ipmovie("silence frame\n");
 417             url_fseek(pb, opcode_size, SEEK_CUR);
 418             break;
 419
 420         case OPCODE_INIT_VIDEO_MODE:
 421             debug_ipmovie("initialize video mode\n");
 422             url_fseek(pb, opcode_size, SEEK_CUR);
 423             break;
 424
 425         case OPCODE_CREATE_GRADIENT:
 426             debug_ipmovie("create gradient\n");
 427             url_fseek(pb, opcode_size, SEEK_CUR);
 428             break;
 429
 430         case OPCODE_SET_PALETTE:
 431             debug_ipmovie("set palette\n");
 432             /* check for the logical maximum palette size
 433              * (3 * 256 + 4 bytes) */
 434             if (opcode_size > 0x304) {
 435                 debug_ipmovie("demux_ipmovie: set_palette opcode too large\n");
 436                 chunk_type = CHUNK_BAD;
 437                 break;
 438             }
 439             if (get_buffer(pb, scratch, opcode_size) != opcode_size) {
 440                 chunk_type = CHUNK_BAD;
 441                 break;
 442             }
 443
 444             /* load the palette into internal data structure */
 445             first_color = AV_RL16(&scratch[0]);
 446             last_color = first_color + AV_RL16(&scratch[2]) - 1;
 447             /* sanity check (since they are 16 bit values) */
 448             if ((first_color > 0xFF) || (last_color > 0xFF)) {
 449                 debug_ipmovie("demux_ipmovie: set_palette indexes out of range (%d -> %d)\n",
 450                     first_color, last_color);
 451                 chunk_type = CHUNK_BAD;
 452                 break;
 453             }
 454             j = 4;  /* offset of first palette data */
 455             for (i = first_color; i <= last_color; i++) {
 456                 /* the palette is stored as a 6-bit VGA palette, thus each
 457                  * component is shifted up to a 8-bit range */
 458                 r = scratch[j++] * 4;
 459                 g = scratch[j++] * 4;
 460                 b = scratch[j++] * 4;
 461                 s->palette_control.palette[i] = (r << 16) | (g << 8) | (b);
 462             }
 463             /* indicate a palette change */
 464             s->palette_control.palette_changed = 1;
 465             break;
 466
 467         case OPCODE_SET_PALETTE_COMPRESSED:
 468             debug_ipmovie("set palette compressed\n");
 469             url_fseek(pb, opcode_size, SEEK_CUR);
 470             break;
 471
 472         case OPCODE_SET_DECODING_MAP:
 473             debug_ipmovie("set decoding map\n");
 474
 475             /* log position and move on for now */
 476             s->decode_map_chunk_offset = url_ftell(pb);
 477             s->decode_map_chunk_size = opcode_size;
 478             url_fseek(pb, opcode_size, SEEK_CUR);
 479             break;
 480
 481         case OPCODE_VIDEO_DATA:
 482             debug_ipmovie("set video data\n");
 483
 484             /* log position and move on for now */
 485             s->video_chunk_offset = url_ftell(pb);
 486             s->video_chunk_size = opcode_size;
 487             url_fseek(pb, opcode_size, SEEK_CUR);
 488             break;
 489
 490         default:
 491             debug_ipmovie("*** unknown opcode type\n");
 492             chunk_type = CHUNK_BAD;
 493             break;
 494
 495         }
 496     }
 497
 498     /* make a note of where the stream is sitting */
 499     s->next_chunk_offset = url_ftell(pb);
 500
 501     /* dispatch the first of any pending packets */
 502     if ((chunk_type == CHUNK_VIDEO) || (chunk_type == CHUNK_AUDIO_ONLY))
 503         chunk_type = load_ipmovie_packet(s, pb, pkt);
 504
 505     return chunk_type;
 506 }
 507
 508 static int ipmovie_probe(AVProbeData *p)
 509 {
 510     if (strncmp(p->buf, IPMOVIE_SIGNATURE, IPMOVIE_SIGNATURE_SIZE) != 0)
 511         return 0;
 512
 513     return AVPROBE_SCORE_MAX;
 514 }
 515
 516 static int ipmovie_read_header(AVFormatContext *s,
 517                                AVFormatParameters *ap)
 518 {
 519     IPMVEContext *ipmovie = s->priv_data;
 520     ByteIOContext *pb = s->pb;
 521     AVPacket pkt;
 522     AVStream *st;
 523     unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
 524     int chunk_type;
 525
 526     /* initialize private context members */
 527     ipmovie->video_pts = ipmovie->audio_frame_count = 0;
 528     ipmovie->audio_chunk_offset = ipmovie->video_chunk_offset =
 529     ipmovie->decode_map_chunk_offset = 0;
 530
 531     /* on the first read, this will position the stream at the first chunk */
 532     ipmovie->next_chunk_offset = IPMOVIE_SIGNATURE_SIZE + 6;
 533
 534     /* process the first chunk which should be CHUNK_INIT_VIDEO */
 535     if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_VIDEO)
 536         return AVERROR_INVALIDDATA;
 537
 538     /* peek ahead to the next chunk-- if it is an init audio chunk, process
 539      * it; if it is the first video chunk, this is a silent file */
 540     if (get_buffer(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
 541         CHUNK_PREAMBLE_SIZE)
 542         return AVERROR(EIO);
 543     chunk_type = AV_RL16(&chunk_preamble[2]);
 544     url_fseek(pb, -CHUNK_PREAMBLE_SIZE, SEEK_CUR);
 545
 546     if (chunk_type == CHUNK_VIDEO)
 547         ipmovie->audio_type = 0;  /* no audio */
 548     else if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_AUDIO)
 549         return AVERROR_INVALIDDATA;
 550
 551     /* initialize the stream decoders */
 552     st = av_new_stream(s, 0);
 553     if (!st)
 554         return AVERROR(ENOMEM);
 555     av_set_pts_info(st, 33, 1, 90000);
 556     ipmovie->video_stream_index = st->index;
 557     st->codec->codec_type = CODEC_TYPE_VIDEO;
 558     st->codec->codec_id = CODEC_ID_INTERPLAY_VIDEO;
 559     st->codec->codec_tag = 0;  /* no fourcc */
 560     st->codec->width = ipmovie->video_width;
 561     st->codec->height = ipmovie->video_height;
 562
 563     /* palette considerations */
 564     st->codec->palctrl = &ipmovie->palette_control;
 565
 566     if (ipmovie->audio_type) {
 567         st = av_new_stream(s, 0);
 568         if (!st)
 569             return AVERROR(ENOMEM);
 570         av_set_pts_info(st, 33, 1, 90000);
 571         ipmovie->audio_stream_index = st->index;
 572         st->codec->codec_type = CODEC_TYPE_AUDIO;
 573         st->codec->codec_id = ipmovie->audio_type;
 574         st->codec->codec_tag = 0;  /* no tag */
 575         st->codec->channels = ipmovie->audio_channels;
 576         st->codec->sample_rate = ipmovie->audio_sample_rate;
 577         st->codec->bits_per_sample = ipmovie->audio_bits;
 578         st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
 579             st->codec->bits_per_sample;
 580         if (st->codec->codec_id == CODEC_ID_INTERPLAY_DPCM)
 581             st->codec->bit_rate /= 2;
 582         st->codec->block_align = st->codec->channels * st->codec->bits_per_sample;
 583     }
 584
 585     return 0;
 586 }
 587
 588 static int ipmovie_read_packet(AVFormatContext *s,
 589                                AVPacket *pkt)
 590 {
 591     IPMVEContext *ipmovie = s->priv_data;
 592     ByteIOContext *pb = s->pb;
 593     int ret;
 594
 595     ret = process_ipmovie_chunk(ipmovie, pb, pkt);
 596     if (ret == CHUNK_BAD)
 597         ret = AVERROR_INVALIDDATA;
 598     else if (ret == CHUNK_EOF)
 599         ret = AVERROR(EIO);
 600     else if (ret == CHUNK_NOMEM)
 601         ret = AVERROR(ENOMEM);
 602     else if (ret == CHUNK_VIDEO)
 603         ret = 0;
 604     else
 605         ret = -1;
 606
 607     return ret;
 608 }
 609
 610 AVInputFormat ipmovie_demuxer = {
 611     "ipmovie",
 612     NULL_IF_CONFIG_SMALL("Interplay MVE format"),
 613     sizeof(IPMVEContext),
 614     ipmovie_probe,
 615     ipmovie_read_header,
 616     ipmovie_read_packet,
 617 };