libavformat/ffm.c

   1 /*
   2  * FFM (ffserver live feed) muxer and demuxer
   3  * Copyright (c) 2001 Fabrice Bellard.
   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 #include "avformat.h"
  22 #include <unistd.h>
  23
  24 /* The FFM file is made of blocks of fixed size */
  25 #define FFM_HEADER_SIZE 14
  26 #define PACKET_ID       0x666d
  27
  28 /* each packet contains frames (which can span several packets */
  29 #define FRAME_HEADER_SIZE    8
  30 #define FLAG_KEY_FRAME       0x01
  31
  32 typedef struct FFMStream {
  33     int64_t pts;
  34 } FFMStream;
  35
  36 enum {
  37     READ_HEADER,
  38     READ_DATA,
  39 };
  40
  41 typedef struct FFMContext {
  42     /* only reading mode */
  43     offset_t write_index, file_size;
  44     int read_state;
  45     uint8_t header[FRAME_HEADER_SIZE];
  46
  47     /* read and write */
  48     int first_packet; /* true if first packet, needed to set the discontinuity tag */
  49     int first_frame_in_packet; /* true if first frame in packet, needed to know if PTS information is valid */
  50     int packet_size;
  51     int frame_offset;
  52     int64_t pts;
  53     uint8_t *packet_ptr, *packet_end;
  54     uint8_t packet[FFM_PACKET_SIZE];
  55 } FFMContext;
  56
  57 static int64_t get_pts(AVFormatContext *s, offset_t pos);
  58
  59 /* disable pts hack for testing */
  60 int ffm_nopts = 0;
  61
  62 #ifdef CONFIG_MUXERS
  63 static void flush_packet(AVFormatContext *s)
  64 {
  65     FFMContext *ffm = s->priv_data;
  66     int fill_size, h;
  67     ByteIOContext *pb = &s->pb;
  68
  69     fill_size = ffm->packet_end - ffm->packet_ptr;
  70     memset(ffm->packet_ptr, 0, fill_size);
  71
  72     if (url_ftell(pb) % ffm->packet_size)
  73         av_abort();
  74
  75     /* put header */
  76     put_be16(pb, PACKET_ID);
  77     put_be16(pb, fill_size);
  78     put_be64(pb, ffm->pts);
  79     h = ffm->frame_offset;
  80     if (ffm->first_packet)
  81         h |= 0x8000;
  82     put_be16(pb, h);
  83     put_buffer(pb, ffm->packet, ffm->packet_end - ffm->packet);
  84     put_flush_packet(pb);
  85
  86     /* prepare next packet */
  87     ffm->frame_offset = 0; /* no key frame */
  88     ffm->pts = 0; /* no pts */
  89     ffm->packet_ptr = ffm->packet;
  90     ffm->first_packet = 0;
  91 }
  92
  93 /* 'first' is true if first data of a frame */
  94 static void ffm_write_data(AVFormatContext *s,
  95                            const uint8_t *buf, int size,
  96                            int64_t pts, int first)
  97 {
  98     FFMContext *ffm = s->priv_data;
  99     int len;
 100
 101     if (first && ffm->frame_offset == 0)
 102         ffm->frame_offset = ffm->packet_ptr - ffm->packet + FFM_HEADER_SIZE;
 103     if (first && ffm->pts == 0)
 104         ffm->pts = pts;
 105
 106     /* write as many packets as needed */
 107     while (size > 0) {
 108         len = ffm->packet_end - ffm->packet_ptr;
 109         if (len > size)
 110             len = size;
 111         memcpy(ffm->packet_ptr, buf, len);
 112
 113         ffm->packet_ptr += len;
 114         buf += len;
 115         size -= len;
 116         if (ffm->packet_ptr >= ffm->packet_end) {
 117             /* special case : no pts in packet : we leave the current one */
 118             if (ffm->pts == 0)
 119                 ffm->pts = pts;
 120
 121             flush_packet(s);
 122         }
 123     }
 124 }
 125
 126 static int ffm_write_header(AVFormatContext *s)
 127 {
 128     FFMContext *ffm = s->priv_data;
 129     AVStream *st;
 130     FFMStream *fst;
 131     ByteIOContext *pb = &s->pb;
 132     AVCodecContext *codec;
 133     int bit_rate, i;
 134
 135     ffm->packet_size = FFM_PACKET_SIZE;
 136
 137     /* header */
 138     put_le32(pb, MKTAG('F', 'F', 'M', '1'));
 139     put_be32(pb, ffm->packet_size);
 140     /* XXX: store write position in other file ? */
 141     put_be64(pb, ffm->packet_size); /* current write position */
 142
 143     put_be32(pb, s->nb_streams);
 144     bit_rate = 0;
 145     for(i=0;i<s->nb_streams;i++) {
 146         st = s->streams[i];
 147         bit_rate += st->codec->bit_rate;
 148     }
 149     put_be32(pb, bit_rate);
 150
 151     /* list of streams */
 152     for(i=0;i<s->nb_streams;i++) {
 153         st = s->streams[i];
 154         fst = av_mallocz(sizeof(FFMStream));
 155         if (!fst)
 156             goto fail;
 157         av_set_pts_info(st, 64, 1, 1000000);
 158         st->priv_data = fst;
 159
 160         codec = st->codec;
 161         /* generic info */
 162         put_be32(pb, codec->codec_id);
 163         put_byte(pb, codec->codec_type);
 164         put_be32(pb, codec->bit_rate);
 165         put_be32(pb, st->quality);
 166         put_be32(pb, codec->flags);
 167         put_be32(pb, codec->flags2);
 168         put_be32(pb, codec->debug);
 169         /* specific info */
 170         switch(codec->codec_type) {
 171         case CODEC_TYPE_VIDEO:
 172             put_be32(pb, codec->time_base.num);
 173             put_be32(pb, codec->time_base.den);
 174             put_be16(pb, codec->width);
 175             put_be16(pb, codec->height);
 176             put_be16(pb, codec->gop_size);
 177             put_be32(pb, codec->pix_fmt);
 178             put_byte(pb, codec->qmin);
 179             put_byte(pb, codec->qmax);
 180             put_byte(pb, codec->max_qdiff);
 181             put_be16(pb, (int) (codec->qcompress * 10000.0));
 182             put_be16(pb, (int) (codec->qblur * 10000.0));
 183             put_be32(pb, codec->bit_rate_tolerance);
 184             put_strz(pb, codec->rc_eq);
 185             put_be32(pb, codec->rc_max_rate);
 186             put_be32(pb, codec->rc_min_rate);
 187             put_be32(pb, codec->rc_buffer_size);
 188             put_be64(pb, av_dbl2int(codec->i_quant_factor));
 189             put_be64(pb, av_dbl2int(codec->b_quant_factor));
 190             put_be64(pb, av_dbl2int(codec->i_quant_offset));
 191             put_be64(pb, av_dbl2int(codec->b_quant_offset));
 192             put_be32(pb, codec->dct_algo);
 193             put_be32(pb, codec->strict_std_compliance);
 194             put_be32(pb, codec->max_b_frames);
 195             put_be32(pb, codec->luma_elim_threshold);
 196             put_be32(pb, codec->chroma_elim_threshold);
 197             put_be32(pb, codec->mpeg_quant);
 198             put_be32(pb, codec->intra_dc_precision);
 199             put_be32(pb, codec->me_method);
 200             put_be32(pb, codec->mb_decision);
 201             put_be32(pb, codec->nsse_weight);
 202             put_be32(pb, codec->frame_skip_cmp);
 203             put_be64(pb, av_dbl2int(codec->rc_buffer_aggressivity));
 204             break;
 205         case CODEC_TYPE_AUDIO:
 206             put_be32(pb, codec->sample_rate);
 207             put_le16(pb, codec->channels);
 208             put_le16(pb, codec->frame_size);
 209             break;
 210         default:
 211             return -1;
 212         }
 213         /* hack to have real time */
 214         if (ffm_nopts)
 215             fst->pts = 0;
 216         else
 217             fst->pts = av_gettime();
 218     }
 219
 220     /* flush until end of block reached */
 221     while ((url_ftell(pb) % ffm->packet_size) != 0)
 222         put_byte(pb, 0);
 223
 224     put_flush_packet(pb);
 225
 226     /* init packet mux */
 227     ffm->packet_ptr = ffm->packet;
 228     ffm->packet_end = ffm->packet + ffm->packet_size - FFM_HEADER_SIZE;
 229     assert(ffm->packet_end >= ffm->packet);
 230     ffm->frame_offset = 0;
 231     ffm->pts = 0;
 232     ffm->first_packet = 1;
 233
 234     return 0;
 235  fail:
 236     for(i=0;i<s->nb_streams;i++) {
 237         st = s->streams[i];
 238         av_freep(&st->priv_data);
 239     }
 240     return -1;
 241 }
 242
 243 static int ffm_write_packet(AVFormatContext *s, AVPacket *pkt)
 244 {
 245     AVStream *st = s->streams[pkt->stream_index];
 246     FFMStream *fst = st->priv_data;
 247     int64_t pts;
 248     uint8_t header[FRAME_HEADER_SIZE];
 249     int duration;
 250     int size= pkt->size;
 251
 252     //XXX/FIXME use duration from pkt
 253     if (st->codec->codec_type == CODEC_TYPE_AUDIO) {
 254         duration = ((float)st->codec->frame_size / st->codec->sample_rate * 1000000.0);
 255     } else {
 256         duration = (1000000.0 * st->codec->time_base.num / (float)st->codec->time_base.den);
 257     }
 258
 259     pts = fst->pts;
 260     /* packet size & key_frame */
 261     header[0] = pkt->stream_index;
 262     header[1] = 0;
 263     if (pkt->flags & PKT_FLAG_KEY)
 264         header[1] |= FLAG_KEY_FRAME;
 265     header[2] = (size >> 16) & 0xff;
 266     header[3] = (size >> 8) & 0xff;
 267     header[4] = size & 0xff;
 268     header[5] = (duration >> 16) & 0xff;
 269     header[6] = (duration >> 8) & 0xff;
 270     header[7] = duration & 0xff;
 271     ffm_write_data(s, header, FRAME_HEADER_SIZE, pts, 1);
 272     ffm_write_data(s, pkt->data, size, pts, 0);
 273
 274     fst->pts += duration;
 275     return 0;
 276 }
 277
 278 static int ffm_write_trailer(AVFormatContext *s)
 279 {
 280     ByteIOContext *pb = &s->pb;
 281     FFMContext *ffm = s->priv_data;
 282
 283     /* flush packets */
 284     if (ffm->packet_ptr > ffm->packet)
 285         flush_packet(s);
 286
 287     put_flush_packet(pb);
 288
 289     if (!url_is_streamed(pb)) {
 290         int64_t size;
 291         /* update the write offset */
 292         size = url_ftell(pb);
 293         url_fseek(pb, 8, SEEK_SET);
 294         put_be64(pb, size);
 295         put_flush_packet(pb);
 296     }
 297
 298     return 0;
 299 }
 300 #endif //CONFIG_MUXERS
 301
 302 /* ffm demux */
 303
 304 static int ffm_is_avail_data(AVFormatContext *s, int size)
 305 {
 306     FFMContext *ffm = s->priv_data;
 307     offset_t pos, avail_size;
 308     int len;
 309
 310     len = ffm->packet_end - ffm->packet_ptr;
 311     if (!ffm_nopts) {
 312         /* XXX: I don't understand this test, so I disabled it for testing */
 313         if (size <= len)
 314             return 1;
 315     }
 316     pos = url_ftell(&s->pb);
 317     if (pos == ffm->write_index) {
 318         /* exactly at the end of stream */
 319         return 0;
 320     } else if (pos < ffm->write_index) {
 321         avail_size = ffm->write_index - pos;
 322     } else {
 323         avail_size = (ffm->file_size - pos) + (ffm->write_index - FFM_PACKET_SIZE);
 324     }
 325     avail_size = (avail_size / ffm->packet_size) * (ffm->packet_size - FFM_HEADER_SIZE) + len;
 326     if (size <= avail_size)
 327         return 1;
 328     else
 329         return 0;
 330 }
 331
 332 /* first is true if we read the frame header */
 333 static int ffm_read_data(AVFormatContext *s,
 334                          uint8_t *buf, int size, int first)
 335 {
 336     FFMContext *ffm = s->priv_data;
 337     ByteIOContext *pb = &s->pb;
 338     int len, fill_size, size1, frame_offset;
 339
 340     size1 = size;
 341     while (size > 0) {
 342     redo:
 343         len = ffm->packet_end - ffm->packet_ptr;
 344         if (len > size)
 345             len = size;
 346         if (len == 0) {
 347             if (url_ftell(pb) == ffm->file_size)
 348                 url_fseek(pb, ffm->packet_size, SEEK_SET);
 349     retry_read:
 350             get_be16(pb); /* PACKET_ID */
 351             fill_size = get_be16(pb);
 352             ffm->pts = get_be64(pb);
 353             ffm->first_frame_in_packet = 1;
 354             frame_offset = get_be16(pb);
 355             get_buffer(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);
 356             ffm->packet_end = ffm->packet + (ffm->packet_size - FFM_HEADER_SIZE - fill_size);
 357             if (ffm->packet_end < ffm->packet)
 358                 return -1;
 359             /* if first packet or resynchronization packet, we must
 360                handle it specifically */
 361             if (ffm->first_packet || (frame_offset & 0x8000)) {
 362                 if (!frame_offset) {
 363                     /* This packet has no frame headers in it */
 364                     if (url_ftell(pb) >= ffm->packet_size * 3) {
 365                         url_fseek(pb, -ffm->packet_size * 2, SEEK_CUR);
 366                         goto retry_read;
 367                     }
 368                     /* This is bad, we cannot find a valid frame header */
 369                     return 0;
 370                 }
 371                 ffm->first_packet = 0;
 372                 if ((frame_offset & 0x7ffff) < FFM_HEADER_SIZE)
 373                     return -1;
 374                 ffm->packet_ptr = ffm->packet + (frame_offset & 0x7fff) - FFM_HEADER_SIZE;
 375                 if (!first)
 376                     break;
 377             } else {
 378                 ffm->packet_ptr = ffm->packet;
 379             }
 380             goto redo;
 381         }
 382         memcpy(buf, ffm->packet_ptr, len);
 383         buf += len;
 384         ffm->packet_ptr += len;
 385         size -= len;
 386         first = 0;
 387     }
 388     return size1 - size;
 389 }
 390
 391
 392 static void adjust_write_index(AVFormatContext *s)
 393 {
 394     FFMContext *ffm = s->priv_data;
 395     ByteIOContext *pb = &s->pb;
 396     int64_t pts;
 397     //offset_t orig_write_index = ffm->write_index;
 398     offset_t pos_min, pos_max;
 399     int64_t pts_start;
 400     offset_t ptr = url_ftell(pb);
 401
 402
 403     pos_min = 0;
 404     pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
 405
 406     pts_start = get_pts(s, pos_min);
 407
 408     pts = get_pts(s, pos_max);
 409
 410     if (pts - 100000 > pts_start)
 411         goto end;
 412
 413     ffm->write_index = FFM_PACKET_SIZE;
 414
 415     pts_start = get_pts(s, pos_min);
 416
 417     pts = get_pts(s, pos_max);
 418
 419     if (pts - 100000 <= pts_start) {
 420         while (1) {
 421             offset_t newpos;
 422             int64_t newpts;
 423
 424             newpos = ((pos_max + pos_min) / (2 * FFM_PACKET_SIZE)) * FFM_PACKET_SIZE;
 425
 426             if (newpos == pos_min)
 427                 break;
 428
 429             newpts = get_pts(s, newpos);
 430
 431             if (newpts - 100000 <= pts) {
 432                 pos_max = newpos;
 433                 pts = newpts;
 434             } else {
 435                 pos_min = newpos;
 436             }
 437         }
 438         ffm->write_index += pos_max;
 439     }
 440
 441     //printf("Adjusted write index from %"PRId64" to %"PRId64": pts=%0.6f\n", orig_write_index, ffm->write_index, pts / 1000000.);
 442     //printf("pts range %0.6f - %0.6f\n", get_pts(s, 0) / 1000000. , get_pts(s, ffm->file_size - 2 * FFM_PACKET_SIZE) / 1000000. );
 443
 444  end:
 445     url_fseek(pb, ptr, SEEK_SET);
 446 }
 447
 448
 449 static int ffm_read_header(AVFormatContext *s, AVFormatParameters *ap)
 450 {
 451     FFMContext *ffm = s->priv_data;
 452     AVStream *st;
 453     FFMStream *fst;
 454     ByteIOContext *pb = &s->pb;
 455     AVCodecContext *codec;
 456     int i, nb_streams;
 457     uint32_t tag;
 458
 459     /* header */
 460     tag = get_le32(pb);
 461     if (tag != MKTAG('F', 'F', 'M', '1'))
 462         goto fail;
 463     ffm->packet_size = get_be32(pb);
 464     if (ffm->packet_size != FFM_PACKET_SIZE)
 465         goto fail;
 466     ffm->write_index = get_be64(pb);
 467     /* get also filesize */
 468     if (!url_is_streamed(pb)) {
 469         ffm->file_size = url_fsize(pb);
 470         adjust_write_index(s);
 471     } else {
 472         ffm->file_size = (UINT64_C(1) << 63) - 1;
 473     }
 474
 475     nb_streams = get_be32(pb);
 476     get_be32(pb); /* total bitrate */
 477     /* read each stream */
 478     for(i=0;i<nb_streams;i++) {
 479         char rc_eq_buf[128];
 480
 481         st = av_new_stream(s, 0);
 482         if (!st)
 483             goto fail;
 484         fst = av_mallocz(sizeof(FFMStream));
 485         if (!fst)
 486             goto fail;
 487         s->streams[i] = st;
 488
 489         av_set_pts_info(st, 64, 1, 1000000);
 490
 491         st->priv_data = fst;
 492
 493         codec = st->codec;
 494         /* generic info */
 495         codec->codec_id = get_be32(pb);
 496         codec->codec_type = get_byte(pb); /* codec_type */
 497         codec->bit_rate = get_be32(pb);
 498         st->quality = get_be32(pb);
 499         codec->flags = get_be32(pb);
 500         codec->flags2 = get_be32(pb);
 501         codec->debug = get_be32(pb);
 502         /* specific info */
 503         switch(codec->codec_type) {
 504         case CODEC_TYPE_VIDEO:
 505             codec->time_base.num = get_be32(pb);
 506             codec->time_base.den = get_be32(pb);
 507             codec->width = get_be16(pb);
 508             codec->height = get_be16(pb);
 509             codec->gop_size = get_be16(pb);
 510             codec->pix_fmt = get_be32(pb);
 511             codec->qmin = get_byte(pb);
 512             codec->qmax = get_byte(pb);
 513             codec->max_qdiff = get_byte(pb);
 514             codec->qcompress = get_be16(pb) / 10000.0;
 515             codec->qblur = get_be16(pb) / 10000.0;
 516             codec->bit_rate_tolerance = get_be32(pb);
 517             codec->rc_eq = av_strdup(get_strz(pb, rc_eq_buf, sizeof(rc_eq_buf)));
 518             codec->rc_max_rate = get_be32(pb);
 519             codec->rc_min_rate = get_be32(pb);
 520             codec->rc_buffer_size = get_be32(pb);
 521             codec->i_quant_factor = av_int2dbl(get_be64(pb));
 522             codec->b_quant_factor = av_int2dbl(get_be64(pb));
 523             codec->i_quant_offset = av_int2dbl(get_be64(pb));
 524             codec->b_quant_offset = av_int2dbl(get_be64(pb));
 525             codec->dct_algo = get_be32(pb);
 526             codec->strict_std_compliance = get_be32(pb);
 527             codec->max_b_frames = get_be32(pb);
 528             codec->luma_elim_threshold = get_be32(pb);
 529             codec->chroma_elim_threshold = get_be32(pb);
 530             codec->mpeg_quant = get_be32(pb);
 531             codec->intra_dc_precision = get_be32(pb);
 532             codec->me_method = get_be32(pb);
 533             codec->mb_decision = get_be32(pb);
 534             codec->nsse_weight = get_be32(pb);
 535             codec->frame_skip_cmp = get_be32(pb);
 536             codec->rc_buffer_aggressivity = av_int2dbl(get_be64(pb));
 537             break;
 538         case CODEC_TYPE_AUDIO:
 539             codec->sample_rate = get_be32(pb);
 540             codec->channels = get_le16(pb);
 541             codec->frame_size = get_le16(pb);
 542             break;
 543         default:
 544             goto fail;
 545         }
 546
 547     }
 548
 549     /* get until end of block reached */
 550     while ((url_ftell(pb) % ffm->packet_size) != 0)
 551         get_byte(pb);
 552
 553     /* init packet demux */
 554     ffm->packet_ptr = ffm->packet;
 555     ffm->packet_end = ffm->packet;
 556     ffm->frame_offset = 0;
 557     ffm->pts = 0;
 558     ffm->read_state = READ_HEADER;
 559     ffm->first_packet = 1;
 560     return 0;
 561  fail:
 562     for(i=0;i<s->nb_streams;i++) {
 563         st = s->streams[i];
 564         if (st) {
 565             av_freep(&st->priv_data);
 566             av_free(st);
 567         }
 568     }
 569     return -1;
 570 }
 571
 572 /* return < 0 if eof */
 573 static int ffm_read_packet(AVFormatContext *s, AVPacket *pkt)
 574 {
 575     int size;
 576     FFMContext *ffm = s->priv_data;
 577     int duration;
 578
 579     switch(ffm->read_state) {
 580     case READ_HEADER:
 581         if (!ffm_is_avail_data(s, FRAME_HEADER_SIZE)) {
 582             return -EAGAIN;
 583         }
 584 #if 0
 585         printf("pos=%08"PRIx64" spos=%"PRIx64", write_index=%"PRIx64" size=%"PRIx64"\n",
 586                url_ftell(&s->pb), s->pb.pos, ffm->write_index, ffm->file_size);
 587 #endif
 588         if (ffm_read_data(s, ffm->header, FRAME_HEADER_SIZE, 1) !=
 589             FRAME_HEADER_SIZE)
 590             return -EAGAIN;
 591 #if 0
 592         {
 593             int i;
 594             for(i=0;i<FRAME_HEADER_SIZE;i++)
 595                 printf("%02x ", ffm->header[i]);
 596             printf("\n");
 597         }
 598 #endif
 599         ffm->read_state = READ_DATA;
 600         /* fall thru */
 601     case READ_DATA:
 602         size = (ffm->header[2] << 16) | (ffm->header[3] << 8) | ffm->header[4];
 603         if (!ffm_is_avail_data(s, size)) {
 604             return -EAGAIN;
 605         }
 606
 607         duration = (ffm->header[5] << 16) | (ffm->header[6] << 8) | ffm->header[7];
 608
 609         av_new_packet(pkt, size);
 610         pkt->stream_index = ffm->header[0];
 611         pkt->pos = url_ftell(&s->pb);
 612         if (ffm->header[1] & FLAG_KEY_FRAME)
 613             pkt->flags |= PKT_FLAG_KEY;
 614
 615         ffm->read_state = READ_HEADER;
 616         if (ffm_read_data(s, pkt->data, size, 0) != size) {
 617             /* bad case: desynchronized packet. we cancel all the packet loading */
 618             av_free_packet(pkt);
 619             return -EAGAIN;
 620         }
 621         if (ffm->first_frame_in_packet)
 622         {
 623             pkt->pts = ffm->pts;
 624             ffm->first_frame_in_packet = 0;
 625         }
 626         pkt->duration = duration;
 627         break;
 628     }
 629     return 0;
 630 }
 631
 632 //#define DEBUG_SEEK
 633
 634 /* pos is between 0 and file_size - FFM_PACKET_SIZE. It is translated
 635    by the write position inside this function */
 636 static void ffm_seek1(AVFormatContext *s, offset_t pos1)
 637 {
 638     FFMContext *ffm = s->priv_data;
 639     ByteIOContext *pb = &s->pb;
 640     offset_t pos;
 641
 642     pos = pos1 + ffm->write_index;
 643     if (pos >= ffm->file_size)
 644         pos -= (ffm->file_size - FFM_PACKET_SIZE);
 645 #ifdef DEBUG_SEEK
 646     printf("seek to %"PRIx64" -> %"PRIx64"\n", pos1, pos);
 647 #endif
 648     url_fseek(pb, pos, SEEK_SET);
 649 }
 650
 651 static int64_t get_pts(AVFormatContext *s, offset_t pos)
 652 {
 653     ByteIOContext *pb = &s->pb;
 654     int64_t pts;
 655
 656     ffm_seek1(s, pos);
 657     url_fskip(pb, 4);
 658     pts = get_be64(pb);
 659 #ifdef DEBUG_SEEK
 660     printf("pts=%0.6f\n", pts / 1000000.0);
 661 #endif
 662     return pts;
 663 }
 664
 665 /* seek to a given time in the file. The file read pointer is
 666    positionned at or before pts. XXX: the following code is quite
 667    approximative */
 668 static int ffm_seek(AVFormatContext *s, int stream_index, int64_t wanted_pts, int flags)
 669 {
 670     FFMContext *ffm = s->priv_data;
 671     offset_t pos_min, pos_max, pos;
 672     int64_t pts_min, pts_max, pts;
 673     double pos1;
 674
 675 #ifdef DEBUG_SEEK
 676     printf("wanted_pts=%0.6f\n", wanted_pts / 1000000.0);
 677 #endif
 678     /* find the position using linear interpolation (better than
 679        dichotomy in typical cases) */
 680     pos_min = 0;
 681     pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
 682     while (pos_min <= pos_max) {
 683         pts_min = get_pts(s, pos_min);
 684         pts_max = get_pts(s, pos_max);
 685         /* linear interpolation */
 686         pos1 = (double)(pos_max - pos_min) * (double)(wanted_pts - pts_min) /
 687             (double)(pts_max - pts_min);
 688         pos = (((int64_t)pos1) / FFM_PACKET_SIZE) * FFM_PACKET_SIZE;
 689         if (pos <= pos_min)
 690             pos = pos_min;
 691         else if (pos >= pos_max)
 692             pos = pos_max;
 693         pts = get_pts(s, pos);
 694         /* check if we are lucky */
 695         if (pts == wanted_pts) {
 696             goto found;
 697         } else if (pts > wanted_pts) {
 698             pos_max = pos - FFM_PACKET_SIZE;
 699         } else {
 700             pos_min = pos + FFM_PACKET_SIZE;
 701         }
 702     }
 703     pos = (flags & AVSEEK_FLAG_BACKWARD) ? pos_min : pos_max;
 704     if (pos > 0)
 705         pos -= FFM_PACKET_SIZE;
 706  found:
 707     ffm_seek1(s, pos);
 708     return 0;
 709 }
 710
 711 #ifdef CONFIG_FFSERVER
 712 offset_t ffm_read_write_index(int fd)
 713 {
 714     uint8_t buf[8];
 715     offset_t pos;
 716     int i;
 717
 718     lseek(fd, 8, SEEK_SET);
 719     read(fd, buf, 8);
 720     pos = 0;
 721     for(i=0;i<8;i++)
 722         pos |= (int64_t)buf[i] << (56 - i * 8);
 723     return pos;
 724 }
 725
 726 void ffm_write_write_index(int fd, offset_t pos)
 727 {
 728     uint8_t buf[8];
 729     int i;
 730
 731     for(i=0;i<8;i++)
 732         buf[i] = (pos >> (56 - i * 8)) & 0xff;
 733     lseek(fd, 8, SEEK_SET);
 734     write(fd, buf, 8);
 735 }
 736
 737 void ffm_set_write_index(AVFormatContext *s, offset_t pos, offset_t file_size)
 738 {
 739     FFMContext *ffm = s->priv_data;
 740     ffm->write_index = pos;
 741     ffm->file_size = file_size;
 742 }
 743 #endif // CONFIG_FFSERVER
 744
 745 static int ffm_read_close(AVFormatContext *s)
 746 {
 747     AVStream *st;
 748     int i;
 749
 750     for(i=0;i<s->nb_streams;i++) {
 751         st = s->streams[i];
 752         av_freep(&st->priv_data);
 753     }
 754     return 0;
 755 }
 756
 757 static int ffm_probe(AVProbeData *p)
 758 {
 759     if (p->buf_size >= 4 &&
 760         p->buf[0] == 'F' && p->buf[1] == 'F' && p->buf[2] == 'M' &&
 761         p->buf[3] == '1')
 762         return AVPROBE_SCORE_MAX + 1;
 763     return 0;
 764 }
 765
 766 #ifdef CONFIG_FFM_DEMUXER
 767 AVInputFormat ffm_demuxer = {
 768     "ffm",
 769     "ffm format",
 770     sizeof(FFMContext),
 771     ffm_probe,
 772     ffm_read_header,
 773     ffm_read_packet,
 774     ffm_read_close,
 775     ffm_seek,
 776 };
 777 #endif
 778 #ifdef CONFIG_FFM_MUXER
 779 AVOutputFormat ffm_muxer = {
 780     "ffm",
 781     "ffm format",
 782     "",
 783     "ffm",
 784     sizeof(FFMContext),
 785     /* not really used */
 786     CODEC_ID_MP2,
 787     CODEC_ID_MPEG1VIDEO,
 788     ffm_write_header,
 789     ffm_write_packet,
 790     ffm_write_trailer,
 791 };
 792 #endif //CONFIG_FFM_MUXER