FFmpeg: libavformat/ipmovie.c Source File

00001 /*
00002  * Interplay MVE File Demuxer
00003  * Copyright (c) 2003 The ffmpeg Project
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00035 #include "libavutil/intreadwrite.h"
00036 #include "avformat.h"
00037 
00038 #define CHUNK_PREAMBLE_SIZE 4
00039 #define OPCODE_PREAMBLE_SIZE 4
00040 
00041 #define CHUNK_INIT_AUDIO   0x0000
00042 #define CHUNK_AUDIO_ONLY   0x0001
00043 #define CHUNK_INIT_VIDEO   0x0002
00044 #define CHUNK_VIDEO        0x0003
00045 #define CHUNK_SHUTDOWN     0x0004
00046 #define CHUNK_END          0x0005
00047 /* these last types are used internally */
00048 #define CHUNK_DONE         0xFFFC
00049 #define CHUNK_NOMEM        0xFFFD
00050 #define CHUNK_EOF          0xFFFE
00051 #define CHUNK_BAD          0xFFFF
00052 
00053 #define OPCODE_END_OF_STREAM           0x00
00054 #define OPCODE_END_OF_CHUNK            0x01
00055 #define OPCODE_CREATE_TIMER            0x02
00056 #define OPCODE_INIT_AUDIO_BUFFERS      0x03
00057 #define OPCODE_START_STOP_AUDIO        0x04
00058 #define OPCODE_INIT_VIDEO_BUFFERS      0x05
00059 #define OPCODE_UNKNOWN_06              0x06
00060 #define OPCODE_SEND_BUFFER             0x07
00061 #define OPCODE_AUDIO_FRAME             0x08
00062 #define OPCODE_SILENCE_FRAME           0x09
00063 #define OPCODE_INIT_VIDEO_MODE         0x0A
00064 #define OPCODE_CREATE_GRADIENT         0x0B
00065 #define OPCODE_SET_PALETTE             0x0C
00066 #define OPCODE_SET_PALETTE_COMPRESSED  0x0D
00067 #define OPCODE_UNKNOWN_0E              0x0E
00068 #define OPCODE_SET_DECODING_MAP        0x0F
00069 #define OPCODE_UNKNOWN_10              0x10
00070 #define OPCODE_VIDEO_DATA              0x11
00071 #define OPCODE_UNKNOWN_12              0x12
00072 #define OPCODE_UNKNOWN_13              0x13
00073 #define OPCODE_UNKNOWN_14              0x14
00074 #define OPCODE_UNKNOWN_15              0x15
00075 
00076 #define PALETTE_COUNT 256
00077 
00078 typedef struct IPMVEContext {
00079 
00080     unsigned char *buf;
00081     int buf_size;
00082 
00083     uint64_t frame_pts_inc;
00084 
00085     unsigned int video_bpp;
00086     unsigned int video_width;
00087     unsigned int video_height;
00088     int64_t video_pts;
00089     uint32_t     palette[256];
00090     int          has_palette;
00091 
00092     unsigned int audio_bits;
00093     unsigned int audio_channels;
00094     unsigned int audio_sample_rate;
00095     enum CodecID audio_type;
00096     unsigned int audio_frame_count;
00097 
00098     int video_stream_index;
00099     int audio_stream_index;
00100 
00101     int64_t audio_chunk_offset;
00102     int audio_chunk_size;
00103     int64_t video_chunk_offset;
00104     int video_chunk_size;
00105     int64_t decode_map_chunk_offset;
00106     int decode_map_chunk_size;
00107 
00108     int64_t next_chunk_offset;
00109 
00110 } IPMVEContext;
00111 
00112 static int load_ipmovie_packet(IPMVEContext *s, AVIOContext *pb,
00113     AVPacket *pkt) {
00114 
00115     int chunk_type;
00116 
00117     if (s->audio_chunk_offset) {
00118 
00119         /* adjust for PCM audio by skipping chunk header */
00120         if (s->audio_type != CODEC_ID_INTERPLAY_DPCM) {
00121             s->audio_chunk_offset += 6;
00122             s->audio_chunk_size -= 6;
00123         }
00124 
00125         avio_seek(pb, s->audio_chunk_offset, SEEK_SET);
00126         s->audio_chunk_offset = 0;
00127 
00128         if (s->audio_chunk_size != av_get_packet(pb, pkt, s->audio_chunk_size))
00129             return CHUNK_EOF;
00130 
00131         pkt->stream_index = s->audio_stream_index;
00132         pkt->pts = s->audio_frame_count;
00133 
00134         /* audio frame maintenance */
00135         if (s->audio_type != CODEC_ID_INTERPLAY_DPCM)
00136             s->audio_frame_count +=
00137             (s->audio_chunk_size / s->audio_channels / (s->audio_bits / 8));
00138         else
00139             s->audio_frame_count +=
00140                 (s->audio_chunk_size - 6) / s->audio_channels;
00141 
00142         av_dlog(NULL, "sending audio frame with pts %"PRId64" (%d audio frames)\n",
00143                 pkt->pts, s->audio_frame_count);
00144 
00145         chunk_type = CHUNK_VIDEO;
00146 
00147     } else if (s->decode_map_chunk_offset) {
00148 
00149         /* send both the decode map and the video data together */
00150 
00151         if (av_new_packet(pkt, s->decode_map_chunk_size + s->video_chunk_size))
00152             return CHUNK_NOMEM;
00153 
00154         if (s->has_palette) {
00155             uint8_t *pal;
00156 
00157             pal = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE,
00158                                           AVPALETTE_SIZE);
00159             if (pal) {
00160                 memcpy(pal, s->palette, AVPALETTE_SIZE);
00161                 s->has_palette = 0;
00162             }
00163         }
00164 
00165         pkt->pos= s->decode_map_chunk_offset;
00166         avio_seek(pb, s->decode_map_chunk_offset, SEEK_SET);
00167         s->decode_map_chunk_offset = 0;
00168 
00169         if (avio_read(pb, pkt->data, s->decode_map_chunk_size) !=
00170             s->decode_map_chunk_size) {
00171             av_free_packet(pkt);
00172             return CHUNK_EOF;
00173         }
00174 
00175         avio_seek(pb, s->video_chunk_offset, SEEK_SET);
00176         s->video_chunk_offset = 0;
00177 
00178         if (avio_read(pb, pkt->data + s->decode_map_chunk_size,
00179             s->video_chunk_size) != s->video_chunk_size) {
00180             av_free_packet(pkt);
00181             return CHUNK_EOF;
00182         }
00183 
00184         pkt->stream_index = s->video_stream_index;
00185         pkt->pts = s->video_pts;
00186 
00187         av_dlog(NULL, "sending video frame with pts %"PRId64"\n", pkt->pts);
00188 
00189         s->video_pts += s->frame_pts_inc;
00190 
00191         chunk_type = CHUNK_VIDEO;
00192 
00193     } else {
00194 
00195         avio_seek(pb, s->next_chunk_offset, SEEK_SET);
00196         chunk_type = CHUNK_DONE;
00197 
00198     }
00199 
00200     return chunk_type;
00201 }
00202 
00203 /* This function loads and processes a single chunk in an IP movie file.
00204  * It returns the type of chunk that was processed. */
00205 static int process_ipmovie_chunk(IPMVEContext *s, AVIOContext *pb,
00206     AVPacket *pkt)
00207 {
00208     unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
00209     int chunk_type;
00210     int chunk_size;
00211     unsigned char opcode_preamble[OPCODE_PREAMBLE_SIZE];
00212     unsigned char opcode_type;
00213     unsigned char opcode_version;
00214     int opcode_size;
00215     unsigned char scratch[1024];
00216     int i, j;
00217     int first_color, last_color;
00218     int audio_flags;
00219     unsigned char r, g, b;
00220 
00221     /* see if there are any pending packets */
00222     chunk_type = load_ipmovie_packet(s, pb, pkt);
00223     if (chunk_type != CHUNK_DONE)
00224         return chunk_type;
00225 
00226     /* read the next chunk, wherever the file happens to be pointing */
00227     if (url_feof(pb))
00228         return CHUNK_EOF;
00229     if (avio_read(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
00230         CHUNK_PREAMBLE_SIZE)
00231         return CHUNK_BAD;
00232     chunk_size = AV_RL16(&chunk_preamble[0]);
00233     chunk_type = AV_RL16(&chunk_preamble[2]);
00234 
00235     av_dlog(NULL, "chunk type 0x%04X, 0x%04X bytes: ", chunk_type, chunk_size);
00236 
00237     switch (chunk_type) {
00238 
00239     case CHUNK_INIT_AUDIO:
00240         av_dlog(NULL, "initialize audio\n");
00241         break;
00242 
00243     case CHUNK_AUDIO_ONLY:
00244         av_dlog(NULL, "audio only\n");
00245         break;
00246 
00247     case CHUNK_INIT_VIDEO:
00248         av_dlog(NULL, "initialize video\n");
00249         break;
00250 
00251     case CHUNK_VIDEO:
00252         av_dlog(NULL, "video (and audio)\n");
00253         break;
00254 
00255     case CHUNK_SHUTDOWN:
00256         av_dlog(NULL, "shutdown\n");
00257         break;
00258 
00259     case CHUNK_END:
00260         av_dlog(NULL, "end\n");
00261         break;
00262 
00263     default:
00264         av_dlog(NULL, "invalid chunk\n");
00265         chunk_type = CHUNK_BAD;
00266         break;
00267 
00268     }
00269 
00270     while ((chunk_size > 0) && (chunk_type != CHUNK_BAD)) {
00271 
00272         /* read the next chunk, wherever the file happens to be pointing */
00273         if (url_feof(pb)) {
00274             chunk_type = CHUNK_EOF;
00275             break;
00276         }
00277         if (avio_read(pb, opcode_preamble, CHUNK_PREAMBLE_SIZE) !=
00278             CHUNK_PREAMBLE_SIZE) {
00279             chunk_type = CHUNK_BAD;
00280             break;
00281         }
00282 
00283         opcode_size = AV_RL16(&opcode_preamble[0]);
00284         opcode_type = opcode_preamble[2];
00285         opcode_version = opcode_preamble[3];
00286 
00287         chunk_size -= OPCODE_PREAMBLE_SIZE;
00288         chunk_size -= opcode_size;
00289         if (chunk_size < 0) {
00290             av_dlog(NULL, "chunk_size countdown just went negative\n");
00291             chunk_type = CHUNK_BAD;
00292             break;
00293         }
00294 
00295         av_dlog(NULL, "  opcode type %02X, version %d, 0x%04X bytes: ",
00296                 opcode_type, opcode_version, opcode_size);
00297         switch (opcode_type) {
00298 
00299         case OPCODE_END_OF_STREAM:
00300             av_dlog(NULL, "end of stream\n");
00301             avio_skip(pb, opcode_size);
00302             break;
00303 
00304         case OPCODE_END_OF_CHUNK:
00305             av_dlog(NULL, "end of chunk\n");
00306             avio_skip(pb, opcode_size);
00307             break;
00308 
00309         case OPCODE_CREATE_TIMER:
00310             av_dlog(NULL, "create timer\n");
00311             if ((opcode_version > 0) || (opcode_size > 6)) {
00312                 av_dlog(NULL, "bad create_timer opcode\n");
00313                 chunk_type = CHUNK_BAD;
00314                 break;
00315             }
00316             if (avio_read(pb, scratch, opcode_size) !=
00317                 opcode_size) {
00318                 chunk_type = CHUNK_BAD;
00319                 break;
00320             }
00321             s->frame_pts_inc = ((uint64_t)AV_RL32(&scratch[0])) * AV_RL16(&scratch[4]);
00322             av_dlog(NULL, "  %.2f frames/second (timer div = %d, subdiv = %d)\n",
00323                     1000000.0 / s->frame_pts_inc, AV_RL32(&scratch[0]),
00324                     AV_RL16(&scratch[4]));
00325             break;
00326 
00327         case OPCODE_INIT_AUDIO_BUFFERS:
00328             av_dlog(NULL, "initialize audio buffers\n");
00329             if ((opcode_version > 1) || (opcode_size > 10)) {
00330                 av_dlog(NULL, "bad init_audio_buffers opcode\n");
00331                 chunk_type = CHUNK_BAD;
00332                 break;
00333             }
00334             if (avio_read(pb, scratch, opcode_size) !=
00335                 opcode_size) {
00336                 chunk_type = CHUNK_BAD;
00337                 break;
00338             }
00339             s->audio_sample_rate = AV_RL16(&scratch[4]);
00340             audio_flags = AV_RL16(&scratch[2]);
00341             /* bit 0 of the flags: 0 = mono, 1 = stereo */
00342             s->audio_channels = (audio_flags & 1) + 1;
00343             /* bit 1 of the flags: 0 = 8 bit, 1 = 16 bit */
00344             s->audio_bits = (((audio_flags >> 1) & 1) + 1) * 8;
00345             /* bit 2 indicates compressed audio in version 1 opcode */
00346             if ((opcode_version == 1) && (audio_flags & 0x4))
00347                 s->audio_type = CODEC_ID_INTERPLAY_DPCM;
00348             else if (s->audio_bits == 16)
00349                 s->audio_type = CODEC_ID_PCM_S16LE;
00350             else
00351                 s->audio_type = CODEC_ID_PCM_U8;
00352             av_dlog(NULL, "audio: %d bits, %d Hz, %s, %s format\n",
00353                     s->audio_bits, s->audio_sample_rate,
00354                     (s->audio_channels == 2) ? "stereo" : "mono",
00355                     (s->audio_type == CODEC_ID_INTERPLAY_DPCM) ?
00356                     "Interplay audio" : "PCM");
00357             break;
00358 
00359         case OPCODE_START_STOP_AUDIO:
00360             av_dlog(NULL, "start/stop audio\n");
00361             avio_skip(pb, opcode_size);
00362             break;
00363 
00364         case OPCODE_INIT_VIDEO_BUFFERS:
00365             av_dlog(NULL, "initialize video buffers\n");
00366             if ((opcode_version > 2) || (opcode_size > 8)) {
00367                 av_dlog(NULL, "bad init_video_buffers opcode\n");
00368                 chunk_type = CHUNK_BAD;
00369                 break;
00370             }
00371             if (avio_read(pb, scratch, opcode_size) !=
00372                 opcode_size) {
00373                 chunk_type = CHUNK_BAD;
00374                 break;
00375             }
00376             s->video_width = AV_RL16(&scratch[0]) * 8;
00377             s->video_height = AV_RL16(&scratch[2]) * 8;
00378             if (opcode_version < 2 || !AV_RL16(&scratch[6])) {
00379                 s->video_bpp = 8;
00380             } else {
00381                 s->video_bpp = 16;
00382             }
00383             av_dlog(NULL, "video resolution: %d x %d\n",
00384                     s->video_width, s->video_height);
00385             break;
00386 
00387         case OPCODE_UNKNOWN_06:
00388         case OPCODE_UNKNOWN_0E:
00389         case OPCODE_UNKNOWN_10:
00390         case OPCODE_UNKNOWN_12:
00391         case OPCODE_UNKNOWN_13:
00392         case OPCODE_UNKNOWN_14:
00393         case OPCODE_UNKNOWN_15:
00394             av_dlog(NULL, "unknown (but documented) opcode %02X\n", opcode_type);
00395             avio_skip(pb, opcode_size);
00396             break;
00397 
00398         case OPCODE_SEND_BUFFER:
00399             av_dlog(NULL, "send buffer\n");
00400             avio_skip(pb, opcode_size);
00401             break;
00402 
00403         case OPCODE_AUDIO_FRAME:
00404             av_dlog(NULL, "audio frame\n");
00405 
00406             /* log position and move on for now */
00407             s->audio_chunk_offset = avio_tell(pb);
00408             s->audio_chunk_size = opcode_size;
00409             avio_skip(pb, opcode_size);
00410             break;
00411 
00412         case OPCODE_SILENCE_FRAME:
00413             av_dlog(NULL, "silence frame\n");
00414             avio_skip(pb, opcode_size);
00415             break;
00416 
00417         case OPCODE_INIT_VIDEO_MODE:
00418             av_dlog(NULL, "initialize video mode\n");
00419             avio_skip(pb, opcode_size);
00420             break;
00421 
00422         case OPCODE_CREATE_GRADIENT:
00423             av_dlog(NULL, "create gradient\n");
00424             avio_skip(pb, opcode_size);
00425             break;
00426 
00427         case OPCODE_SET_PALETTE:
00428             av_dlog(NULL, "set palette\n");
00429             /* check for the logical maximum palette size
00430              * (3 * 256 + 4 bytes) */
00431             if (opcode_size > 0x304) {
00432                 av_dlog(NULL, "demux_ipmovie: set_palette opcode too large\n");
00433                 chunk_type = CHUNK_BAD;
00434                 break;
00435             }
00436             if (avio_read(pb, scratch, opcode_size) != opcode_size) {
00437                 chunk_type = CHUNK_BAD;
00438                 break;
00439             }
00440 
00441             /* load the palette into internal data structure */
00442             first_color = AV_RL16(&scratch[0]);
00443             last_color = first_color + AV_RL16(&scratch[2]) - 1;
00444             /* sanity check (since they are 16 bit values) */
00445             if ((first_color > 0xFF) || (last_color > 0xFF)) {
00446                 av_dlog(NULL, "demux_ipmovie: set_palette indexes out of range (%d -> %d)\n",
00447                     first_color, last_color);
00448                 chunk_type = CHUNK_BAD;
00449                 break;
00450             }
00451             j = 4;  /* offset of first palette data */
00452             for (i = first_color; i <= last_color; i++) {
00453                 /* the palette is stored as a 6-bit VGA palette, thus each
00454                  * component is shifted up to a 8-bit range */
00455                 r = scratch[j++] * 4;
00456                 g = scratch[j++] * 4;
00457                 b = scratch[j++] * 4;
00458                 s->palette[i] = (r << 16) | (g << 8) | (b);
00459             }
00460             s->has_palette = 1;
00461             break;
00462 
00463         case OPCODE_SET_PALETTE_COMPRESSED:
00464             av_dlog(NULL, "set palette compressed\n");
00465             avio_skip(pb, opcode_size);
00466             break;
00467 
00468         case OPCODE_SET_DECODING_MAP:
00469             av_dlog(NULL, "set decoding map\n");
00470 
00471             /* log position and move on for now */
00472             s->decode_map_chunk_offset = avio_tell(pb);
00473             s->decode_map_chunk_size = opcode_size;
00474             avio_skip(pb, opcode_size);
00475             break;
00476 
00477         case OPCODE_VIDEO_DATA:
00478             av_dlog(NULL, "set video data\n");
00479 
00480             /* log position and move on for now */
00481             s->video_chunk_offset = avio_tell(pb);
00482             s->video_chunk_size = opcode_size;
00483             avio_skip(pb, opcode_size);
00484             break;
00485 
00486         default:
00487             av_dlog(NULL, "*** unknown opcode type\n");
00488             chunk_type = CHUNK_BAD;
00489             break;
00490 
00491         }
00492     }
00493 
00494     /* make a note of where the stream is sitting */
00495     s->next_chunk_offset = avio_tell(pb);
00496 
00497     /* dispatch the first of any pending packets */
00498     if ((chunk_type == CHUNK_VIDEO) || (chunk_type == CHUNK_AUDIO_ONLY))
00499         chunk_type = load_ipmovie_packet(s, pb, pkt);
00500 
00501     return chunk_type;
00502 }
00503 
00504 static const char signature[] = "Interplay MVE File\x1A\0\x1A";
00505 
00506 static int ipmovie_probe(AVProbeData *p)
00507 {
00508     uint8_t *b = p->buf;
00509     uint8_t *b_end = p->buf + p->buf_size - sizeof(signature);
00510     do {
00511         if (memcmp(b++, signature, sizeof(signature)) == 0)
00512             return AVPROBE_SCORE_MAX;
00513     } while (b < b_end);
00514 
00515     return 0;
00516 }
00517 
00518 static int ipmovie_read_header(AVFormatContext *s,
00519                                AVFormatParameters *ap)
00520 {
00521     IPMVEContext *ipmovie = s->priv_data;
00522     AVIOContext *pb = s->pb;
00523     AVPacket pkt;
00524     AVStream *st;
00525     unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
00526     int chunk_type;
00527     uint8_t signature_buffer[sizeof(signature)];
00528 
00529     avio_read(pb, signature_buffer, sizeof(signature_buffer));
00530     while (memcmp(signature_buffer, signature, sizeof(signature))) {
00531         memmove(signature_buffer, signature_buffer + 1, sizeof(signature_buffer) - 1);
00532         signature_buffer[sizeof(signature_buffer) - 1] = avio_r8(pb);
00533         if (url_feof(pb))
00534             return AVERROR_EOF;
00535     }
00536     /* initialize private context members */
00537     ipmovie->video_pts = ipmovie->audio_frame_count = 0;
00538     ipmovie->audio_chunk_offset = ipmovie->video_chunk_offset =
00539     ipmovie->decode_map_chunk_offset = 0;
00540 
00541     /* on the first read, this will position the stream at the first chunk */
00542     ipmovie->next_chunk_offset = avio_tell(pb) + 4;
00543 
00544     /* process the first chunk which should be CHUNK_INIT_VIDEO */
00545     if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_VIDEO)
00546         return AVERROR_INVALIDDATA;
00547 
00548     /* peek ahead to the next chunk-- if it is an init audio chunk, process
00549      * it; if it is the first video chunk, this is a silent file */
00550     if (avio_read(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
00551         CHUNK_PREAMBLE_SIZE)
00552         return AVERROR(EIO);
00553     chunk_type = AV_RL16(&chunk_preamble[2]);
00554     avio_seek(pb, -CHUNK_PREAMBLE_SIZE, SEEK_CUR);
00555 
00556     if (chunk_type == CHUNK_VIDEO)
00557         ipmovie->audio_type = CODEC_ID_NONE;  /* no audio */
00558     else if (process_ipmovie_chunk(ipmovie, pb, &pkt) != CHUNK_INIT_AUDIO)
00559         return AVERROR_INVALIDDATA;
00560 
00561     /* initialize the stream decoders */
00562     st = av_new_stream(s, 0);
00563     if (!st)
00564         return AVERROR(ENOMEM);
00565     av_set_pts_info(st, 63, 1, 1000000);
00566     ipmovie->video_stream_index = st->index;
00567     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
00568     st->codec->codec_id = CODEC_ID_INTERPLAY_VIDEO;
00569     st->codec->codec_tag = 0;  /* no fourcc */
00570     st->codec->width = ipmovie->video_width;
00571     st->codec->height = ipmovie->video_height;
00572     st->codec->bits_per_coded_sample = ipmovie->video_bpp;
00573 
00574     if (ipmovie->audio_type) {
00575         st = av_new_stream(s, 0);
00576         if (!st)
00577             return AVERROR(ENOMEM);
00578         av_set_pts_info(st, 32, 1, ipmovie->audio_sample_rate);
00579         ipmovie->audio_stream_index = st->index;
00580         st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
00581         st->codec->codec_id = ipmovie->audio_type;
00582         st->codec->codec_tag = 0;  /* no tag */
00583         st->codec->channels = ipmovie->audio_channels;
00584         st->codec->sample_rate = ipmovie->audio_sample_rate;
00585         st->codec->bits_per_coded_sample = ipmovie->audio_bits;
00586         st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
00587             st->codec->bits_per_coded_sample;
00588         if (st->codec->codec_id == CODEC_ID_INTERPLAY_DPCM)
00589             st->codec->bit_rate /= 2;
00590         st->codec->block_align = st->codec->channels * st->codec->bits_per_coded_sample;
00591     }
00592 
00593     return 0;
00594 }
00595 
00596 static int ipmovie_read_packet(AVFormatContext *s,
00597                                AVPacket *pkt)
00598 {
00599     IPMVEContext *ipmovie = s->priv_data;
00600     AVIOContext *pb = s->pb;
00601     int ret;
00602 
00603     ret = process_ipmovie_chunk(ipmovie, pb, pkt);
00604     if (ret == CHUNK_BAD)
00605         ret = AVERROR_INVALIDDATA;
00606     else if (ret == CHUNK_EOF)
00607         ret = AVERROR(EIO);
00608     else if (ret == CHUNK_NOMEM)
00609         ret = AVERROR(ENOMEM);
00610     else if (ret == CHUNK_VIDEO)
00611         ret = 0;
00612     else
00613         ret = -1;
00614 
00615     return ret;
00616 }
00617 
00618 AVInputFormat ff_ipmovie_demuxer = {
00619     "ipmovie",
00620     NULL_IF_CONFIG_SMALL("Interplay MVE format"),
00621     sizeof(IPMVEContext),
00622     ipmovie_probe,
00623     ipmovie_read_header,
00624     ipmovie_read_packet,
00625 };