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FFmpeg/libavformat/ffmdec.c

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  1. /*

  2.  * FFM (ffserver live feed) 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. 

  22. #include <stdint.h>

  23. 

  24. #include "libavutil/intreadwrite.h"

  25. #include "libavutil/intfloat.h"

  26. #include "avformat.h"

  27. #include "internal.h"

  28. #include "ffm.h"

  29. #include "avio_internal.h"

  30. 

  31. static int ffm_is_avail_data(AVFormatContext *s, int size)

  32. {

  33.     FFMContext *ffm = s->priv_data;

  34.     int64_t pos, avail_size;

  35.     int len;

  36. 

  37.     len = ffm->packet_end - ffm->packet_ptr;

  38.     if (size <= len)

  39.         return 1;

  40.     pos = avio_tell(s->pb);

  41.     if (!ffm->write_index) {

  42.         if (pos == ffm->file_size)

  43.             return AVERROR_EOF;

  44.         avail_size = ffm->file_size - pos;

  45.     } else {

  46.     if (pos == ffm->write_index) {

  47.         /* exactly at the end of stream */

  48.         return AVERROR(EAGAIN);

  49.     } else if (pos < ffm->write_index) {

  50.         avail_size = ffm->write_index - pos;

  51.     } else {

  52.         avail_size = (ffm->file_size - pos) + (ffm->write_index - FFM_PACKET_SIZE);

  53.     }

  54.     }

  55.     avail_size = (avail_size / ffm->packet_size) * (ffm->packet_size - FFM_HEADER_SIZE) + len;

  56.     if (size <= avail_size)

  57.         return 1;

  58.     else

  59.         return AVERROR(EAGAIN);

  60. }

  61. 

  62. static int ffm_resync(AVFormatContext *s, int state)

  63. {

  64.     av_log(s, AV_LOG_ERROR, "resyncing\n");

  65.     while (state != PACKET_ID) {

  66.         if (avio_feof(s->pb)) {

  67.             av_log(s, AV_LOG_ERROR, "cannot find FFM syncword\n");

  68.             return -1;

  69.         }

  70.         state = (state << 8) | avio_r8(s->pb);

  71.     }

  72.     return 0;

  73. }

  74. 

  75. /* first is true if we read the frame header */

  76. static int ffm_read_data(AVFormatContext *s,

  77.                          uint8_t *buf, int size, int header)

  78. {

  79.     FFMContext *ffm = s->priv_data;

  80.     AVIOContext *pb = s->pb;

  81.     int len, fill_size, size1, frame_offset, id;

  82.     int64_t last_pos = -1;

  83. 

  84.     size1 = size;

  85.     while (size > 0) {

  86.     redo:

  87.         len = ffm->packet_end - ffm->packet_ptr;

  88.         if (len < 0)

  89.             return -1;

  90.         if (len > size)

  91.             len = size;

  92.         if (len == 0) {

  93.             if (avio_tell(pb) == ffm->file_size)

  94.                 avio_seek(pb, ffm->packet_size, SEEK_SET);

  95.     retry_read:

  96.             if (pb->buffer_size != ffm->packet_size) {

  97.                 int64_t tell = avio_tell(pb);

  98.                 ffio_set_buf_size(pb, ffm->packet_size);

  99.                 avio_seek(pb, tell, SEEK_SET);

  100.             }

  101.             id = avio_rb16(pb); /* PACKET_ID */

  102.             if (id != PACKET_ID) {

  103.                 if (ffm_resync(s, id) < 0)

  104.                     return -1;

  105.                 last_pos = avio_tell(pb);

  106.             }

  107.             fill_size = avio_rb16(pb);

  108.             ffm->dts = avio_rb64(pb);

  109.             frame_offset = avio_rb16(pb);

  110.             avio_read(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);

  111.             ffm->packet_end = ffm->packet + (ffm->packet_size - FFM_HEADER_SIZE - fill_size);

  112.             if (ffm->packet_end < ffm->packet || frame_offset < 0)

  113.                 return -1;

  114.             /* if first packet or resynchronization packet, we must

  115.                handle it specifically */

  116.             if (ffm->first_packet || (frame_offset & 0x8000)) {

  117.                 if (!frame_offset) {

  118.                     /* This packet has no frame headers in it */

  119.                     if (avio_tell(pb) >= ffm->packet_size * 3LL) {

  120.                         int64_t seekback = FFMIN(ffm->packet_size * 2LL, avio_tell(pb) - last_pos);

  121.                         seekback = FFMAX(seekback, 0);

  122.                         avio_seek(pb, -seekback, SEEK_CUR);

  123.                         goto retry_read;

  124.                     }

  125.                     /* This is bad, we cannot find a valid frame header */

  126.                     return 0;

  127.                 }

  128.                 ffm->first_packet = 0;

  129.                 if ((frame_offset & 0x7fff) < FFM_HEADER_SIZE)

  130.                     return -1;

  131.                 ffm->packet_ptr = ffm->packet + (frame_offset & 0x7fff) - FFM_HEADER_SIZE;

  132.                 if (!header)

  133.                     break;

  134.             } else {

  135.                 ffm->packet_ptr = ffm->packet;

  136.             }

  137.             goto redo;

  138.         }

  139.         memcpy(buf, ffm->packet_ptr, len);

  140.         buf += len;

  141.         ffm->packet_ptr += len;

  142.         size -= len;

  143.         header = 0;

  144.     }

  145.     return size1 - size;

  146. }

  147. 

  148. /* ensure that acutal seeking happens between FFM_PACKET_SIZE

  149.    and file_size - FFM_PACKET_SIZE */

  150. static int64_t ffm_seek1(AVFormatContext *s, int64_t pos1)

  151. {

  152.     FFMContext *ffm = s->priv_data;

  153.     AVIOContext *pb = s->pb;

  154.     int64_t pos;

  155. 

  156.     pos = FFMIN(pos1, ffm->file_size - FFM_PACKET_SIZE);

  157.     pos = FFMAX(pos, FFM_PACKET_SIZE);

  158.     av_dlog(s, "seek to %"PRIx64" -> %"PRIx64"\n", pos1, pos);

  159.     return avio_seek(pb, pos, SEEK_SET);

  160. }

  161. 

  162. static int64_t get_dts(AVFormatContext *s, int64_t pos)

  163. {

  164.     AVIOContext *pb = s->pb;

  165.     int64_t dts;

  166. 

  167.     ffm_seek1(s, pos);

  168.     avio_skip(pb, 4);

  169.     dts = avio_rb64(pb);

  170.     av_dlog(s, "dts=%0.6f\n", dts / 1000000.0);

  171.     return dts;

  172. }

  173. 

  174. static void adjust_write_index(AVFormatContext *s)

  175. {

  176.     FFMContext *ffm = s->priv_data;

  177.     AVIOContext *pb = s->pb;

  178.     int64_t pts;

  179.     //int64_t orig_write_index = ffm->write_index;

  180.     int64_t pos_min, pos_max;

  181.     int64_t pts_start;

  182.     int64_t ptr = avio_tell(pb);

  183. 

  184. 

  185.     pos_min = 0;

  186.     pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;

  187. 

  188.     pts_start = get_dts(s, pos_min);

  189. 

  190.     pts = get_dts(s, pos_max);

  191. 

  192.     if (pts - 100000 > pts_start)

  193.         goto end;

  194. 

  195.     ffm->write_index = FFM_PACKET_SIZE;

  196. 

  197.     pts_start = get_dts(s, pos_min);

  198. 

  199.     pts = get_dts(s, pos_max);

  200. 

  201.     if (pts - 100000 <= pts_start) {

  202.         while (1) {

  203.             int64_t newpos;

  204.             int64_t newpts;

  205. 

  206.             newpos = ((pos_max + pos_min) / (2 * FFM_PACKET_SIZE)) * FFM_PACKET_SIZE;

  207. 

  208.             if (newpos == pos_min)

  209.                 break;

  210. 

  211.             newpts = get_dts(s, newpos);

  212. 

  213.             if (newpts - 100000 <= pts) {

  214.                 pos_max = newpos;

  215.                 pts = newpts;

  216.             } else {

  217.                 pos_min = newpos;

  218.             }

  219.         }

  220.         ffm->write_index += pos_max;

  221.     }

  222. 

  223.  end:

  224.     avio_seek(pb, ptr, SEEK_SET);

  225. }

  226. 

  227. 

  228. static int ffm_close(AVFormatContext *s)

  229. {

  230.     int i;

  231. 

  232.     for (i = 0; i < s->nb_streams; i++)

  233.         av_freep(&s->streams[i]->codec->rc_eq);

  234. 

  235.     return 0;

  236. }

  237. 

  238. static int ffm2_read_header(AVFormatContext *s)

  239. {

  240.     FFMContext *ffm = s->priv_data;

  241.     AVStream *st;

  242.     AVIOContext *pb = s->pb;

  243.     AVCodecContext *codec;

  244.     int ret;

  245. 

  246.     ffm->packet_size = avio_rb32(pb);

  247.     if (ffm->packet_size != FFM_PACKET_SIZE) {

  248.         av_log(s, AV_LOG_ERROR, "Invalid packet size %d, expected size was %d\n",

  249.                ffm->packet_size, FFM_PACKET_SIZE);

  250.         ret = AVERROR_INVALIDDATA;

  251.         goto fail;

  252.     }

  253. 

  254.     ffm->write_index = avio_rb64(pb);

  255.     /* get also filesize */

  256.     if (pb->seekable) {

  257.         ffm->file_size = avio_size(pb);

  258.         if (ffm->write_index && 0)

  259.             adjust_write_index(s);

  260.     } else {

  261.         ffm->file_size = (UINT64_C(1) << 63) - 1;

  262.     }

  263. 

  264.     while(!avio_feof(pb)) {

  265.         unsigned id = avio_rb32(pb);

  266.         unsigned size = avio_rb32(pb);

  267.         int64_t next = avio_tell(pb) + size;

  268.         char rc_eq_buf[128];

  269. 

  270.         if(!id)

  271.             break;

  272. 

  273.         switch(id) {

  274.         case MKBETAG('M', 'A', 'I', 'N'):

  275.             avio_rb32(pb); /* nb_streams */

  276.             avio_rb32(pb); /* total bitrate */

  277.             break;

  278.         case MKBETAG('C', 'O', 'M', 'M'):

  279.             st = avformat_new_stream(s, NULL);

  280.             if (!st) {

  281.                 ret = AVERROR(ENOMEM);

  282.                 goto fail;

  283.             }

  284. 

  285.             avpriv_set_pts_info(st, 64, 1, 1000000);

  286. 

  287.             codec = st->codec;

  288.             /* generic info */

  289.             codec->codec_id = avio_rb32(pb);

  290.             codec->codec_type = avio_r8(pb);

  291.             codec->bit_rate = avio_rb32(pb);

  292.             codec->flags = avio_rb32(pb);

  293.             codec->flags2 = avio_rb32(pb);

  294.             codec->debug = avio_rb32(pb);

  295.             if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {

  296.                 if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)

  297.                     return AVERROR(ENOMEM);

  298.             }

  299.             avio_seek(pb, next, SEEK_SET);

  300.             id = avio_rb32(pb);

  301.             size = avio_rb32(pb);

  302.             next = avio_tell(pb) + size;

  303.             switch(id) {

  304.             case MKBETAG('S', 'T', 'V', 'I'):

  305.                 codec->time_base.num = avio_rb32(pb);

  306.                 codec->time_base.den = avio_rb32(pb);

  307.                 if (codec->time_base.num <= 0 || codec->time_base.den <= 0) {

  308.                     av_log(s, AV_LOG_ERROR, "Invalid time base %d/%d\n",

  309.                            codec->time_base.num, codec->time_base.den);

  310.                     ret = AVERROR_INVALIDDATA;

  311.                     goto fail;

  312.                 }

  313.                 codec->width = avio_rb16(pb);

  314.                 codec->height = avio_rb16(pb);

  315.                 codec->gop_size = avio_rb16(pb);

  316.                 codec->pix_fmt = avio_rb32(pb);

  317.                 codec->qmin = avio_r8(pb);

  318.                 codec->qmax = avio_r8(pb);

  319.                 codec->max_qdiff = avio_r8(pb);

  320.                 codec->qcompress = avio_rb16(pb) / 10000.0;

  321.                 codec->qblur = avio_rb16(pb) / 10000.0;

  322.                 codec->bit_rate_tolerance = avio_rb32(pb);

  323.                 avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));

  324.                 codec->rc_eq = av_strdup(rc_eq_buf);

  325.                 codec->rc_max_rate = avio_rb32(pb);

  326.                 codec->rc_min_rate = avio_rb32(pb);

  327.                 codec->rc_buffer_size = avio_rb32(pb);

  328.                 codec->i_quant_factor = av_int2double(avio_rb64(pb));

  329.                 codec->b_quant_factor = av_int2double(avio_rb64(pb));

  330.                 codec->i_quant_offset = av_int2double(avio_rb64(pb));

  331.                 codec->b_quant_offset = av_int2double(avio_rb64(pb));

  332.                 codec->dct_algo = avio_rb32(pb);

  333.                 codec->strict_std_compliance = avio_rb32(pb);

  334.                 codec->max_b_frames = avio_rb32(pb);

  335.                 codec->mpeg_quant = avio_rb32(pb);

  336.                 codec->intra_dc_precision = avio_rb32(pb);

  337.                 codec->me_method = avio_rb32(pb);

  338.                 codec->mb_decision = avio_rb32(pb);

  339.                 codec->nsse_weight = avio_rb32(pb);

  340.                 codec->frame_skip_cmp = avio_rb32(pb);

  341.                 codec->rc_buffer_aggressivity = av_int2double(avio_rb64(pb));

  342.                 codec->codec_tag = avio_rb32(pb);

  343.                 codec->thread_count = avio_r8(pb);

  344.                 codec->coder_type = avio_rb32(pb);

  345.                 codec->me_cmp = avio_rb32(pb);

  346.                 codec->me_subpel_quality = avio_rb32(pb);

  347.                 codec->me_range = avio_rb32(pb);

  348.                 codec->keyint_min = avio_rb32(pb);

  349.                 codec->scenechange_threshold = avio_rb32(pb);

  350.                 codec->b_frame_strategy = avio_rb32(pb);

  351.                 codec->qcompress = av_int2double(avio_rb64(pb));

  352.                 codec->qblur = av_int2double(avio_rb64(pb));

  353.                 codec->max_qdiff = avio_rb32(pb);

  354.                 codec->refs = avio_rb32(pb);

  355.                 break;

  356.             case MKBETAG('S', 'T', 'A', 'U'):

  357.                 codec->sample_rate = avio_rb32(pb);

  358.                 codec->channels = avio_rl16(pb);

  359.                 codec->frame_size = avio_rl16(pb);

  360.                 break;

  361.             }

  362.             break;

  363.         }

  364.         avio_seek(pb, next, SEEK_SET);

  365.     }

  366. 

  367.     /* get until end of block reached */

  368.     while ((avio_tell(pb) % ffm->packet_size) != 0 && !pb->eof_reached)

  369.         avio_r8(pb);

  370. 

  371.     /* init packet demux */

  372.     ffm->packet_ptr = ffm->packet;

  373.     ffm->packet_end = ffm->packet;

  374.     ffm->frame_offset = 0;

  375.     ffm->dts = 0;

  376.     ffm->read_state = READ_HEADER;

  377.     ffm->first_packet = 1;

  378.     return 0;

  379.  fail:

  380.     ffm_close(s);

  381.     return ret;

  382. }

  383. 

  384. static int ffm_read_header(AVFormatContext *s)

  385. {

  386.     FFMContext *ffm = s->priv_data;

  387.     AVStream *st;

  388.     AVIOContext *pb = s->pb;

  389.     AVCodecContext *codec;

  390.     int i, nb_streams;

  391.     uint32_t tag;

  392. 

  393.     /* header */

  394.     tag = avio_rl32(pb);

  395.     if (tag == MKTAG('F', 'F', 'M', '2'))

  396.         return ffm2_read_header(s);

  397.     if (tag != MKTAG('F', 'F', 'M', '1'))

  398.         goto fail;

  399.     ffm->packet_size = avio_rb32(pb);

  400.     if (ffm->packet_size != FFM_PACKET_SIZE)

  401.         goto fail;

  402.     ffm->write_index = avio_rb64(pb);

  403.     /* get also filesize */

  404.     if (pb->seekable) {

  405.         ffm->file_size = avio_size(pb);

  406.         if (ffm->write_index && 0)

  407.             adjust_write_index(s);

  408.     } else {

  409.         ffm->file_size = (UINT64_C(1) << 63) - 1;

  410.     }

  411. 

  412.     nb_streams = avio_rb32(pb);

  413.     avio_rb32(pb); /* total bitrate */

  414.     /* read each stream */

  415.     for(i=0;i<nb_streams;i++) {

  416.         char rc_eq_buf[128];

  417. 

  418.         st = avformat_new_stream(s, NULL);

  419.         if (!st)

  420.             goto fail;

  421. 

  422.         avpriv_set_pts_info(st, 64, 1, 1000000);

  423. 

  424.         codec = st->codec;

  425.         /* generic info */

  426.         codec->codec_id = avio_rb32(pb);

  427.         codec->codec_type = avio_r8(pb); /* codec_type */

  428.         codec->bit_rate = avio_rb32(pb);

  429.         codec->flags = avio_rb32(pb);

  430.         codec->flags2 = avio_rb32(pb);

  431.         codec->debug = avio_rb32(pb);

  432.         /* specific info */

  433.         switch(codec->codec_type) {

  434.         case AVMEDIA_TYPE_VIDEO:

  435.             codec->time_base.num = avio_rb32(pb);

  436.             codec->time_base.den = avio_rb32(pb);

  437.             if (codec->time_base.num <= 0 || codec->time_base.den <= 0) {

  438.                 av_log(s, AV_LOG_ERROR, "Invalid time base %d/%d\n",

  439.                        codec->time_base.num, codec->time_base.den);

  440.                 goto fail;

  441.             }

  442.             codec->width = avio_rb16(pb);

  443.             codec->height = avio_rb16(pb);

  444.             codec->gop_size = avio_rb16(pb);

  445.             codec->pix_fmt = avio_rb32(pb);

  446.             codec->qmin = avio_r8(pb);

  447.             codec->qmax = avio_r8(pb);

  448.             codec->max_qdiff = avio_r8(pb);

  449.             codec->qcompress = avio_rb16(pb) / 10000.0;

  450.             codec->qblur = avio_rb16(pb) / 10000.0;

  451.             codec->bit_rate_tolerance = avio_rb32(pb);

  452.             avio_get_str(pb, INT_MAX, rc_eq_buf, sizeof(rc_eq_buf));

  453.             codec->rc_eq = av_strdup(rc_eq_buf);

  454.             codec->rc_max_rate = avio_rb32(pb);

  455.             codec->rc_min_rate = avio_rb32(pb);

  456.             codec->rc_buffer_size = avio_rb32(pb);

  457.             codec->i_quant_factor = av_int2double(avio_rb64(pb));

  458.             codec->b_quant_factor = av_int2double(avio_rb64(pb));

  459.             codec->i_quant_offset = av_int2double(avio_rb64(pb));

  460.             codec->b_quant_offset = av_int2double(avio_rb64(pb));

  461.             codec->dct_algo = avio_rb32(pb);

  462.             codec->strict_std_compliance = avio_rb32(pb);

  463.             codec->max_b_frames = avio_rb32(pb);

  464.             codec->mpeg_quant = avio_rb32(pb);

  465.             codec->intra_dc_precision = avio_rb32(pb);

  466.             codec->me_method = avio_rb32(pb);

  467.             codec->mb_decision = avio_rb32(pb);

  468.             codec->nsse_weight = avio_rb32(pb);

  469.             codec->frame_skip_cmp = avio_rb32(pb);

  470.             codec->rc_buffer_aggressivity = av_int2double(avio_rb64(pb));

  471.             codec->codec_tag = avio_rb32(pb);

  472.             codec->thread_count = avio_r8(pb);

  473.             codec->coder_type = avio_rb32(pb);

  474.             codec->me_cmp = avio_rb32(pb);

  475.             codec->me_subpel_quality = avio_rb32(pb);

  476.             codec->me_range = avio_rb32(pb);

  477.             codec->keyint_min = avio_rb32(pb);

  478.             codec->scenechange_threshold = avio_rb32(pb);

  479.             codec->b_frame_strategy = avio_rb32(pb);

  480.             codec->qcompress = av_int2double(avio_rb64(pb));

  481.             codec->qblur = av_int2double(avio_rb64(pb));

  482.             codec->max_qdiff = avio_rb32(pb);

  483.             codec->refs = avio_rb32(pb);

  484.             break;

  485.         case AVMEDIA_TYPE_AUDIO:

  486.             codec->sample_rate = avio_rb32(pb);

  487.             codec->channels = avio_rl16(pb);

  488.             codec->frame_size = avio_rl16(pb);

  489.             break;

  490.         default:

  491.             goto fail;

  492.         }

  493.         if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {

  494.             if (ff_get_extradata(codec, pb, avio_rb32(pb)) < 0)

  495.                 return AVERROR(ENOMEM);

  496.         }

  497.     }

  498. 

  499.     /* get until end of block reached */

  500.     while ((avio_tell(pb) % ffm->packet_size) != 0 && !pb->eof_reached)

  501.         avio_r8(pb);

  502. 

  503.     /* init packet demux */

  504.     ffm->packet_ptr = ffm->packet;

  505.     ffm->packet_end = ffm->packet;

  506.     ffm->frame_offset = 0;

  507.     ffm->dts = 0;

  508.     ffm->read_state = READ_HEADER;

  509.     ffm->first_packet = 1;

  510.     return 0;

  511.  fail:

  512.     ffm_close(s);

  513.     return -1;

  514. }

  515. 

  516. /* return < 0 if eof */

  517. static int ffm_read_packet(AVFormatContext *s, AVPacket *pkt)

  518. {

  519.     int size;

  520.     FFMContext *ffm = s->priv_data;

  521.     int duration, ret;

  522. 

  523.     switch(ffm->read_state) {

  524.     case READ_HEADER:

  525.         if ((ret = ffm_is_avail_data(s, FRAME_HEADER_SIZE+4)) < 0)

  526.             return ret;

  527. 

  528.         av_dlog(s, "pos=%08"PRIx64" spos=%"PRIx64", write_index=%"PRIx64" size=%"PRIx64"\n",

  529.                avio_tell(s->pb), s->pb->pos, ffm->write_index, ffm->file_size);

  530.         if (ffm_read_data(s, ffm->header, FRAME_HEADER_SIZE, 1) !=

  531.             FRAME_HEADER_SIZE)

  532.             return -1;

  533.         if (ffm->header[1] & FLAG_DTS)

  534.             if (ffm_read_data(s, ffm->header+16, 4, 1) != 4)

  535.                 return -1;

  536.         ffm->read_state = READ_DATA;

  537.         /* fall through */

  538.     case READ_DATA:

  539.         size = AV_RB24(ffm->header + 2);

  540.         if ((ret = ffm_is_avail_data(s, size)) < 0)

  541.             return ret;

  542. 

  543.         duration = AV_RB24(ffm->header + 5);

  544. 

  545.         if (av_new_packet(pkt, size) < 0) {

  546.             return AVERROR(ENOMEM);

  547.         }

  548.         pkt->stream_index = ffm->header[0];

  549.         if ((unsigned)pkt->stream_index >= s->nb_streams) {

  550.             av_log(s, AV_LOG_ERROR, "invalid stream index %d\n", pkt->stream_index);

  551.             av_free_packet(pkt);

  552.             ffm->read_state = READ_HEADER;

  553.             return -1;

  554.         }

  555.         pkt->pos = avio_tell(s->pb);

  556.         if (ffm->header[1] & FLAG_KEY_FRAME)

  557.             pkt->flags |= AV_PKT_FLAG_KEY;

  558. 

  559.         ffm->read_state = READ_HEADER;

  560.         if (ffm_read_data(s, pkt->data, size, 0) != size) {

  561.             /* bad case: desynchronized packet. we cancel all the packet loading */

  562.             av_free_packet(pkt);

  563.             return -1;

  564.         }

  565.         pkt->pts = AV_RB64(ffm->header+8);

  566.         if (ffm->header[1] & FLAG_DTS)

  567.             pkt->dts = pkt->pts - AV_RB32(ffm->header+16);

  568.         else

  569.             pkt->dts = pkt->pts;

  570.         pkt->duration = duration;

  571.         break;

  572.     }

  573.     return 0;

  574. }

  575. 

  576. /* seek to a given time in the file. The file read pointer is

  577.    positioned at or before pts. XXX: the following code is quite

  578.    approximative */

  579. static int ffm_seek(AVFormatContext *s, int stream_index, int64_t wanted_pts, int flags)

  580. {

  581.     FFMContext *ffm = s->priv_data;

  582.     int64_t pos_min, pos_max, pos;

  583.     int64_t pts_min, pts_max, pts;

  584.     double pos1;

  585. 

  586.     av_dlog(s, "wanted_pts=%0.6f\n", wanted_pts / 1000000.0);

  587.     /* find the position using linear interpolation (better than

  588.        dichotomy in typical cases) */

  589.     if (ffm->write_index && ffm->write_index < ffm->file_size) {

  590.         if (get_dts(s, FFM_PACKET_SIZE) < wanted_pts) {

  591.             pos_min = FFM_PACKET_SIZE;

  592.             pos_max = ffm->write_index - FFM_PACKET_SIZE;

  593.         } else {

  594.             pos_min = ffm->write_index;

  595.             pos_max = ffm->file_size - FFM_PACKET_SIZE;

  596.         }

  597.     } else {

  598.         pos_min = FFM_PACKET_SIZE;

  599.         pos_max = ffm->file_size - FFM_PACKET_SIZE;

  600.     }

  601.     while (pos_min <= pos_max) {

  602.         pts_min = get_dts(s, pos_min);

  603.         pts_max = get_dts(s, pos_max);

  604.         if (pts_min > wanted_pts || pts_max <= wanted_pts) {

  605.             pos = pts_min > wanted_pts ? pos_min : pos_max;

  606.             goto found;

  607.         }

  608.         /* linear interpolation */

  609.         pos1 = (double)(pos_max - pos_min) * (double)(wanted_pts - pts_min) /

  610.             (double)(pts_max - pts_min);

  611.         pos = (((int64_t)pos1) / FFM_PACKET_SIZE) * FFM_PACKET_SIZE;

  612.         if (pos <= pos_min)

  613.             pos = pos_min;

  614.         else if (pos >= pos_max)

  615.             pos = pos_max;

  616.         pts = get_dts(s, pos);

  617.         /* check if we are lucky */

  618.         if (pts == wanted_pts) {

  619.             goto found;

  620.         } else if (pts > wanted_pts) {

  621.             pos_max = pos - FFM_PACKET_SIZE;

  622.         } else {

  623.             pos_min = pos + FFM_PACKET_SIZE;

  624.         }

  625.     }

  626.     pos = (flags & AVSEEK_FLAG_BACKWARD) ? pos_min : pos_max;

  627. 

  628.  found:

  629.     if (ffm_seek1(s, pos) < 0)

  630.         return -1;

  631. 

  632.     /* reset read state */

  633.     ffm->read_state = READ_HEADER;

  634.     ffm->packet_ptr = ffm->packet;

  635.     ffm->packet_end = ffm->packet;

  636.     ffm->first_packet = 1;

  637. 

  638.     return 0;

  639. }

  640. 

  641. static int ffm_probe(AVProbeData *p)

  642. {

  643.     if (

  644.         p->buf[0] == 'F' && p->buf[1] == 'F' && p->buf[2] == 'M' &&

  645.         (p->buf[3] == '1' || p->buf[3] == '2'))

  646.         return AVPROBE_SCORE_MAX + 1;

  647.     return 0;

  648. }

  649. 

  650. AVInputFormat ff_ffm_demuxer = {

  651.     .name           = "ffm",

  652.     .long_name      = NULL_IF_CONFIG_SMALL("FFM (FFserver live feed)"),

  653.     .priv_data_size = sizeof(FFMContext),

  654.     .read_probe     = ffm_probe,

  655.     .read_header    = ffm_read_header,

  656.     .read_packet    = ffm_read_packet,

  657.     .read_close     = ffm_close,

  658.     .read_seek      = ffm_seek,

  659. };