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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.                 int ret = ffio_set_buf_size(pb, ffm->packet_size);

  99.                 if (ret < 0)

  100.                     return ret;

  101.                 avio_seek(pb, tell, SEEK_SET);

  102.             }

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

  104.             if (id != PACKET_ID) {

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

  106.                     return -1;

  107.                 last_pos = avio_tell(pb);

  108.             }

  109.             fill_size = avio_rb16(pb);

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

  111.             frame_offset = avio_rb16(pb);

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

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

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

  115.                 return -1;

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

  117.                handle it specifically */

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

  119.                 if (!frame_offset) {

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

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

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

  123.                         seekback = FFMAX(seekback, 0);

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

  125.                         goto retry_read;

  126.                     }

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

  128.                     return 0;

  129.                 }

  130.                 ffm->first_packet = 0;

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

  132.                     return -1;

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

  134.                 if (!header)

  135.                     break;

  136.             } else {

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

  138.             }

  139.             goto redo;

  140.         }

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

  142.         buf += len;

  143.         ffm->packet_ptr += len;

  144.         size -= len;

  145.         header = 0;

  146.     }

  147.     return size1 - size;

  148. }

  149. 

  150. /* ensure that acutal seeking happens between FFM_PACKET_SIZE

  151.    and file_size - FFM_PACKET_SIZE */

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

  153. {

  154.     FFMContext *ffm = s->priv_data;

  155.     AVIOContext *pb = s->pb;

  156.     int64_t pos;

  157. 

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

  159.     pos = FFMAX(pos, FFM_PACKET_SIZE);

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

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

  162. }

  163. 

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

  165. {

  166.     AVIOContext *pb = s->pb;

  167.     int64_t dts;

  168. 

  169.     ffm_seek1(s, pos);

  170.     avio_skip(pb, 4);

  171.     dts = avio_rb64(pb);

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

  173.     return dts;

  174. }

  175. 

  176. static void adjust_write_index(AVFormatContext *s)

  177. {

  178.     FFMContext *ffm = s->priv_data;

  179.     AVIOContext *pb = s->pb;

  180.     int64_t pts;

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

  182.     int64_t pos_min, pos_max;

  183.     int64_t pts_start;

  184.     int64_t ptr = avio_tell(pb);

  185. 

  186. 

  187.     pos_min = 0;

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

  189. 

  190.     pts_start = get_dts(s, pos_min);

  191. 

  192.     pts = get_dts(s, pos_max);

  193. 

  194.     if (pts - 100000 > pts_start)

  195.         goto end;

  196. 

  197.     ffm->write_index = FFM_PACKET_SIZE;

  198. 

  199.     pts_start = get_dts(s, pos_min);

  200. 

  201.     pts = get_dts(s, pos_max);

  202. 

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

  204.         while (1) {

  205.             int64_t newpos;

  206.             int64_t newpts;

  207. 

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

  209. 

  210.             if (newpos == pos_min)

  211.                 break;

  212. 

  213.             newpts = get_dts(s, newpos);

  214. 

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

  216.                 pos_max = newpos;

  217.                 pts = newpts;

  218.             } else {

  219.                 pos_min = newpos;

  220.             }

  221.         }

  222.         ffm->write_index += pos_max;

  223.     }

  224. 

  225.  end:

  226.     avio_seek(pb, ptr, SEEK_SET);

  227. }

  228. 

  229. 

  230. static int ffm_close(AVFormatContext *s)

  231. {

  232.     int i;

  233. 

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

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

  236. 

  237.     return 0;

  238. }

  239. 

  240. static int ffm2_read_header(AVFormatContext *s)

  241. {

  242.     FFMContext *ffm = s->priv_data;

  243.     AVStream *st;

  244.     AVIOContext *pb = s->pb;

  245.     AVCodecContext *codec;

  246.     int ret;

  247. 

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

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

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

  251.                ffm->packet_size, FFM_PACKET_SIZE);

  252.         ret = AVERROR_INVALIDDATA;

  253.         goto fail;

  254.     }

  255. 

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

  257.     /* get also filesize */

  258.     if (pb->seekable) {

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

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

  261.             adjust_write_index(s);

  262.     } else {

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

  264.     }

  265. 

  266.     while(!avio_feof(pb)) {

  267.         unsigned id = avio_rb32(pb);

  268.         unsigned size = avio_rb32(pb);

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

  270.         char rc_eq_buf[128];

  271. 

  272.         if(!id)

  273.             break;

  274. 

  275.         switch(id) {

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

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

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

  279.             break;

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

  281.             st = avformat_new_stream(s, NULL);

  282.             if (!st) {

  283.                 ret = AVERROR(ENOMEM);

  284.                 goto fail;

  285.             }

  286. 

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

  288. 

  289.             codec = st->codec;

  290.             /* generic info */

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

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

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

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

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

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

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

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

  299.                     return AVERROR(ENOMEM);

  300.             }

  301.             avio_seek(pb, next, SEEK_SET);

  302.             id = avio_rb32(pb);

  303.             size = avio_rb32(pb);

  304.             next = avio_tell(pb) + size;

  305.             switch(id) {

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

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

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

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

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

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

  312.                     ret = AVERROR_INVALIDDATA;

  313.                     goto fail;

  314.                 }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  357.                 break;

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

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

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

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

  362.                 break;

  363.             }

  364.             break;

  365.         }

  366.         avio_seek(pb, next, SEEK_SET);

  367.     }

  368. 

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

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

  371.         avio_r8(pb);

  372. 

  373.     /* init packet demux */

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

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

  376.     ffm->frame_offset = 0;

  377.     ffm->dts = 0;

  378.     ffm->read_state = READ_HEADER;

  379.     ffm->first_packet = 1;

  380.     return 0;

  381.  fail:

  382.     ffm_close(s);

  383.     return ret;

  384. }

  385. 

  386. static int ffm_read_header(AVFormatContext *s)

  387. {

  388.     FFMContext *ffm = s->priv_data;

  389.     AVStream *st;

  390.     AVIOContext *pb = s->pb;

  391.     AVCodecContext *codec;

  392.     int i, nb_streams;

  393.     uint32_t tag;

  394. 

  395.     /* header */

  396.     tag = avio_rl32(pb);

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

  398.         return ffm2_read_header(s);

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

  400.         goto fail;

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

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

  403.         goto fail;

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

  405.     /* get also filesize */

  406.     if (pb->seekable) {

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

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

  409.             adjust_write_index(s);

  410.     } else {

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

  412.     }

  413. 

  414.     nb_streams = avio_rb32(pb);

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

  416.     /* read each stream */

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

  418.         char rc_eq_buf[128];

  419. 

  420.         st = avformat_new_stream(s, NULL);

  421.         if (!st)

  422.             goto fail;

  423. 

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

  425. 

  426.         codec = st->codec;

  427.         /* generic info */

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

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

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

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

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

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

  434.         /* specific info */

  435.         switch(codec->codec_type) {

  436.         case AVMEDIA_TYPE_VIDEO:

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

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

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

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

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

  442.                 goto fail;

  443.             }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  486.             break;

  487.         case AVMEDIA_TYPE_AUDIO:

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

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

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

  491.             break;

  492.         default:

  493.             goto fail;

  494.         }

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

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

  497.                 return AVERROR(ENOMEM);

  498.         }

  499.     }

  500. 

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

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

  503.         avio_r8(pb);

  504. 

  505.     /* init packet demux */

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

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

  508.     ffm->frame_offset = 0;

  509.     ffm->dts = 0;

  510.     ffm->read_state = READ_HEADER;

  511.     ffm->first_packet = 1;

  512.     return 0;

  513.  fail:

  514.     ffm_close(s);

  515.     return -1;

  516. }

  517. 

  518. /* return < 0 if eof */

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

  520. {

  521.     int size;

  522.     FFMContext *ffm = s->priv_data;

  523.     int duration, ret;

  524. 

  525.     switch(ffm->read_state) {

  526.     case READ_HEADER:

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

  528.             return ret;

  529. 

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

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

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

  533.             FRAME_HEADER_SIZE)

  534.             return -1;

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

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

  537.                 return -1;

  538.         ffm->read_state = READ_DATA;

  539.         /* fall through */

  540.     case READ_DATA:

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

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

  543.             return ret;

  544. 

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

  546. 

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

  548.             return AVERROR(ENOMEM);

  549.         }

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

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

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

  553.             av_free_packet(pkt);

  554.             ffm->read_state = READ_HEADER;

  555.             return -1;

  556.         }

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

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

  559.             pkt->flags |= AV_PKT_FLAG_KEY;

  560. 

  561.         ffm->read_state = READ_HEADER;

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

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

  564.             av_free_packet(pkt);

  565.             return -1;

  566.         }

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

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

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

  570.         else

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

  572.         pkt->duration = duration;

  573.         break;

  574.     }

  575.     return 0;

  576. }

  577. 

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

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

  580.    approximative */

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

  582. {

  583.     FFMContext *ffm = s->priv_data;

  584.     int64_t pos_min, pos_max, pos;

  585.     int64_t pts_min, pts_max, pts;

  586.     double pos1;

  587. 

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

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

  590.        dichotomy in typical cases) */

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

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

  593.             pos_min = FFM_PACKET_SIZE;

  594.             pos_max = ffm->write_index - FFM_PACKET_SIZE;

  595.         } else {

  596.             pos_min = ffm->write_index;

  597.             pos_max = ffm->file_size - FFM_PACKET_SIZE;

  598.         }

  599.     } else {

  600.         pos_min = FFM_PACKET_SIZE;

  601.         pos_max = ffm->file_size - FFM_PACKET_SIZE;

  602.     }

  603.     while (pos_min <= pos_max) {

  604.         pts_min = get_dts(s, pos_min);

  605.         pts_max = get_dts(s, pos_max);

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

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

  608.             goto found;

  609.         }

  610.         /* linear interpolation */

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

  612.             (double)(pts_max - pts_min);

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

  614.         if (pos <= pos_min)

  615.             pos = pos_min;

  616.         else if (pos >= pos_max)

  617.             pos = pos_max;

  618.         pts = get_dts(s, pos);

  619.         /* check if we are lucky */

  620.         if (pts == wanted_pts) {

  621.             goto found;

  622.         } else if (pts > wanted_pts) {

  623.             pos_max = pos - FFM_PACKET_SIZE;

  624.         } else {

  625.             pos_min = pos + FFM_PACKET_SIZE;

  626.         }

  627.     }

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

  629. 

  630.  found:

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

  632.         return -1;

  633. 

  634.     /* reset read state */

  635.     ffm->read_state = READ_HEADER;

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

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

  638.     ffm->first_packet = 1;

  639. 

  640.     return 0;

  641. }

  642. 

  643. static int ffm_probe(AVProbeData *p)

  644. {

  645.     if (

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

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

  648.         return AVPROBE_SCORE_MAX + 1;

  649.     return 0;

  650. }

  651. 

  652. AVInputFormat ff_ffm_demuxer = {

  653.     .name           = "ffm",

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

  655.     .priv_data_size = sizeof(FFMContext),

  656.     .read_probe     = ffm_probe,

  657.     .read_header    = ffm_read_header,

  658.     .read_packet    = ffm_read_packet,

  659.     .read_close     = ffm_close,

  660.     .read_seek      = ffm_seek,

  661. };