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