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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 "libavutil/opt.h"

  27. #include "avformat.h"

  28. #include "internal.h"

  29. #include "ffm.h"

  30. #include "avio_internal.h"

  31. 

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

  33. {

  34.     FFMContext *ffm = s->priv_data;

  35.     int64_t pos, avail_size;

  36.     int len;

  37. 

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

  39.     if (size <= len)

  40.         return 1;

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

  42.     if (!ffm->write_index) {

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

  44.             return AVERROR_EOF;

  45.         avail_size = ffm->file_size - pos;

  46.     } else {

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

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

  49.         return AVERROR(EAGAIN);

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

  51.         avail_size = ffm->write_index - pos;

  52.     } else {

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

  54.     }

  55.     }

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

  57.     if (size <= avail_size)

  58.         return 1;

  59.     else

  60.         return AVERROR(EAGAIN);

  61. }

  62. 

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

  64. {

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

  66.     while (state != PACKET_ID) {

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

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

  69.             return -1;

  70.         }

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

  72.     }

  73.     return 0;

  74. }

  75. 

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

  77. static int ffm_read_data(AVFormatContext *s,

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

  79. {

  80.     FFMContext *ffm = s->priv_data;

  81.     AVIOContext *pb = s->pb;

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

  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.             fill_size = avio_rb16(pb);

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

  107.             frame_offset = avio_rb16(pb);

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

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

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

  111.                 return -1;

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

  113.                handle it specifically */

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

  115.                 if (!frame_offset) {

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

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

  118.                         avio_seek(pb, -ffm->packet_size * 2LL, SEEK_CUR);

  119.                         goto retry_read;

  120.                     }

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

  122.                     return 0;

  123.                 }

  124.                 ffm->first_packet = 0;

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

  126.                     return -1;

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

  128.                 if (!header)

  129.                     break;

  130.             } else {

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

  132.             }

  133.             goto redo;

  134.         }

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

  136.         buf += len;

  137.         ffm->packet_ptr += len;

  138.         size -= len;

  139.         header = 0;

  140.     }

  141.     return size1 - size;

  142. }

  143. 

  144. /* ensure that acutal seeking happens between FFM_PACKET_SIZE

  145.    and file_size - FFM_PACKET_SIZE */

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

  147. {

  148.     FFMContext *ffm = s->priv_data;

  149.     AVIOContext *pb = s->pb;

  150.     int64_t pos;

  151. 

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

  153.     pos = FFMAX(pos, FFM_PACKET_SIZE);

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

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

  156. }

  157. 

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

  159. {

  160.     AVIOContext *pb = s->pb;

  161.     int64_t dts;

  162. 

  163.     ffm_seek1(s, pos);

  164.     avio_skip(pb, 4);

  165.     dts = avio_rb64(pb);

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

  167.     return dts;

  168. }

  169. 

  170. static void adjust_write_index(AVFormatContext *s)

  171. {

  172.     FFMContext *ffm = s->priv_data;

  173.     AVIOContext *pb = s->pb;

  174.     int64_t pts;

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

  176.     int64_t pos_min, pos_max;

  177.     int64_t pts_start;

  178.     int64_t ptr = avio_tell(pb);

  179. 

  180. 

  181.     pos_min = 0;

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

  183. 

  184.     pts_start = get_dts(s, pos_min);

  185. 

  186.     pts = get_dts(s, pos_max);

  187. 

  188.     if (pts - 100000 > pts_start)

  189.         goto end;

  190. 

  191.     ffm->write_index = FFM_PACKET_SIZE;

  192. 

  193.     pts_start = get_dts(s, pos_min);

  194. 

  195.     pts = get_dts(s, pos_max);

  196. 

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

  198.         while (1) {

  199.             int64_t newpos;

  200.             int64_t newpts;

  201. 

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

  203. 

  204.             if (newpos == pos_min)

  205.                 break;

  206. 

  207.             newpts = get_dts(s, newpos);

  208. 

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

  210.                 pos_max = newpos;

  211.                 pts = newpts;

  212.             } else {

  213.                 pos_min = newpos;

  214.             }

  215.         }

  216.         ffm->write_index += pos_max;

  217.     }

  218. 

  219.  end:

  220.     avio_seek(pb, ptr, SEEK_SET);

  221. }

  222. 

  223. 

  224. static int ffm_close(AVFormatContext *s)

  225. {

  226.     int i;

  227. 

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

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

  230. 

  231.     return 0;

  232. }

  233. 

  234. static int ffm2_read_header(AVFormatContext *s)

  235. {

  236.     FFMContext *ffm = s->priv_data;

  237.     AVStream *st;

  238.     AVIOContext *pb = s->pb;

  239.     AVCodecContext *codec;

  240.     int ret;

  241.     int f_main = 0, f_cprv, f_stvi, f_stau;

  242.     AVCodec *enc;

  243.     char *buffer;

  244. 

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

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

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

  248.                ffm->packet_size, FFM_PACKET_SIZE);

  249.         ret = AVERROR_INVALIDDATA;

  250.         goto fail;

  251.     }

  252. 

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

  254.     /* get also filesize */

  255.     if (pb->seekable) {

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

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

  258.             adjust_write_index(s);

  259.     } else {

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

  261.     }

  262. 

  263.     while(!avio_feof(pb)) {

  264.         unsigned id = avio_rb32(pb);

  265.         unsigned size = avio_rb32(pb);

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

  267.         char rc_eq_buf[128];

  268. 

  269.         if(!id)

  270.             break;

  271. 

  272.         switch(id) {

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

  274.             if (f_main++) {

  275.                 ret = AVERROR(EINVAL);

  276.                 goto fail;

  277.             }

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

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

  280.             break;

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

  282.             f_cprv = f_stvi = f_stau = 0;

  283.             st = avformat_new_stream(s, NULL);

  284.             if (!st) {

  285.                 ret = AVERROR(ENOMEM);

  286.                 goto fail;

  287.             }

  288. 

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

  290. 

  291.             codec = st->codec;

  292.             /* generic info */

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

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

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

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

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

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

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

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

  301.                     return AVERROR(ENOMEM);

  302.             }

  303.             break;

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

  305.             if (f_stvi++) {

  306.                 ret = AVERROR(EINVAL);

  307.                 goto fail;

  308.             }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  353.             break;

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

  355.             if (f_stau++) {

  356.                 ret = AVERROR(EINVAL);

  357.                 goto fail;

  358.             }

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

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

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

  362.             break;

  363.         case MKBETAG('C', 'P', 'R', 'V'):

  364.             if (f_cprv++) {

  365.                 ret = AVERROR(EINVAL);

  366.                 goto fail;

  367.             }

  368.             enc = avcodec_find_encoder(codec->codec_id);

  369.             if (enc && enc->priv_data_size && enc->priv_class) {

  370.                 st->recommended_encoder_configuration = av_malloc(size + 1);

  371.                 if (!st->recommended_encoder_configuration) {

  372.                     ret = AVERROR(ENOMEM);

  373.                     goto fail;

  374.                 }

  375.                 avio_get_str(pb, size, st->recommended_encoder_configuration, size + 1);

  376.             }

  377.             break;

  378.         case MKBETAG('S', '2', 'V', 'I'):

  379.             if (f_stvi++) {

  380.                 ret = AVERROR(EINVAL);

  381.                 goto fail;

  382.             }

  383.             buffer = av_malloc(size);

  384.             if (!buffer) {

  385.                 ret = AVERROR(ENOMEM);

  386.                 goto fail;

  387.             }

  388.             avio_get_str(pb, INT_MAX, buffer, size);

  389.             av_set_options_string(codec, buffer, "=", ",");

  390.             av_freep(&buffer);

  391.             break;

  392.         case MKBETAG('S', '2', 'A', 'U'):

  393.             if (f_stau++) {

  394.                 ret = AVERROR(EINVAL);

  395.                 goto fail;

  396.             }

  397.             buffer = av_malloc(size);

  398.             if (!buffer) {

  399.                 ret = AVERROR(ENOMEM);

  400.                 goto fail;

  401.             }

  402.             avio_get_str(pb, INT_MAX, buffer, size);

  403.             av_set_options_string(codec, buffer, "=", ",");

  404.             av_freep(&buffer);

  405.             break;

  406.         }

  407.         avio_seek(pb, next, SEEK_SET);

  408.     }

  409. 

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

  411.     while ((avio_tell(pb) % ffm->packet_size) != 0)

  412.         avio_r8(pb);

  413. 

  414.     /* init packet demux */

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

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

  417.     ffm->frame_offset = 0;

  418.     ffm->dts = 0;

  419.     ffm->read_state = READ_HEADER;

  420.     ffm->first_packet = 1;

  421.     return 0;

  422.  fail:

  423.     ffm_close(s);

  424.     return ret;

  425. }

  426. 

  427. static int ffm_read_header(AVFormatContext *s)

  428. {

  429.     FFMContext *ffm = s->priv_data;

  430.     AVStream *st;

  431.     AVIOContext *pb = s->pb;

  432.     AVCodecContext *codec;

  433.     int i, nb_streams;

  434.     uint32_t tag;

  435. 

  436.     /* header */

  437.     tag = avio_rl32(pb);

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

  439.         return ffm2_read_header(s);

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

  441.         goto fail;

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

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

  444.         goto fail;

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

  446.     /* get also filesize */

  447.     if (pb->seekable) {

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

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

  450.             adjust_write_index(s);

  451.     } else {

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

  453.     }

  454. 

  455.     nb_streams = avio_rb32(pb);

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

  457.     /* read each stream */

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

  459.         char rc_eq_buf[128];

  460. 

  461.         st = avformat_new_stream(s, NULL);

  462.         if (!st)

  463.             goto fail;

  464. 

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

  466. 

  467.         codec = st->codec;

  468.         /* generic info */

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

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

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

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

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

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

  475.         /* specific info */

  476.         switch(codec->codec_type) {

  477.         case AVMEDIA_TYPE_VIDEO:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  522.             break;

  523.         case AVMEDIA_TYPE_AUDIO:

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

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

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

  527.             break;

  528.         default:

  529.             goto fail;

  530.         }

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

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

  533.                 return AVERROR(ENOMEM);

  534.         }

  535.     }

  536. 

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

  538.     while ((avio_tell(pb) % ffm->packet_size) != 0)

  539.         avio_r8(pb);

  540. 

  541.     /* init packet demux */

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

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

  544.     ffm->frame_offset = 0;

  545.     ffm->dts = 0;

  546.     ffm->read_state = READ_HEADER;

  547.     ffm->first_packet = 1;

  548.     return 0;

  549.  fail:

  550.     ffm_close(s);

  551.     return -1;

  552. }

  553. 

  554. /* return < 0 if eof */

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

  556. {

  557.     int size;

  558.     FFMContext *ffm = s->priv_data;

  559.     int duration, ret;

  560. 

  561.     switch(ffm->read_state) {

  562.     case READ_HEADER:

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

  564.             return ret;

  565. 

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

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

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

  569.             FRAME_HEADER_SIZE)

  570.             return -1;

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

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

  573.                 return -1;

  574.         ffm->read_state = READ_DATA;

  575.         /* fall through */

  576.     case READ_DATA:

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

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

  579.             return ret;

  580. 

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

  582. 

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

  584.             return AVERROR(ENOMEM);

  585.         }

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

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

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

  589.             av_free_packet(pkt);

  590.             ffm->read_state = READ_HEADER;

  591.             return -1;

  592.         }

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

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

  595.             pkt->flags |= AV_PKT_FLAG_KEY;

  596. 

  597.         ffm->read_state = READ_HEADER;

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

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

  600.             av_free_packet(pkt);

  601.             return -1;

  602.         }

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

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

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

  606.         else

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

  608.         pkt->duration = duration;

  609.         break;

  610.     }

  611.     return 0;

  612. }

  613. 

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

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

  616.    approximative */

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

  618. {

  619.     FFMContext *ffm = s->priv_data;

  620.     int64_t pos_min, pos_max, pos;

  621.     int64_t pts_min, pts_max, pts;

  622.     double pos1;

  623. 

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

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

  626.        dichotomy in typical cases) */

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

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

  629.             pos_min = FFM_PACKET_SIZE;

  630.             pos_max = ffm->write_index - FFM_PACKET_SIZE;

  631.         } else {

  632.             pos_min = ffm->write_index;

  633.             pos_max = ffm->file_size - FFM_PACKET_SIZE;

  634.         }

  635.     } else {

  636.         pos_min = FFM_PACKET_SIZE;

  637.         pos_max = ffm->file_size - FFM_PACKET_SIZE;

  638.     }

  639.     while (pos_min <= pos_max) {

  640.         pts_min = get_dts(s, pos_min);

  641.         pts_max = get_dts(s, pos_max);

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

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

  644.             goto found;

  645.         }

  646.         /* linear interpolation */

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

  648.             (double)(pts_max - pts_min);

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

  650.         if (pos <= pos_min)

  651.             pos = pos_min;

  652.         else if (pos >= pos_max)

  653.             pos = pos_max;

  654.         pts = get_dts(s, pos);

  655.         /* check if we are lucky */

  656.         if (pts == wanted_pts) {

  657.             goto found;

  658.         } else if (pts > wanted_pts) {

  659.             pos_max = pos - FFM_PACKET_SIZE;

  660.         } else {

  661.             pos_min = pos + FFM_PACKET_SIZE;

  662.         }

  663.     }

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

  665. 

  666.  found:

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

  668.         return -1;

  669. 

  670.     /* reset read state */

  671.     ffm->read_state = READ_HEADER;

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

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

  674.     ffm->first_packet = 1;

  675. 

  676.     return 0;

  677. }

  678. 

  679. static int ffm_probe(AVProbeData *p)

  680. {

  681.     if (

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

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

  684.         return AVPROBE_SCORE_MAX + 1;

  685.     return 0;

  686. }

  687. 

  688. AVInputFormat ff_ffm_demuxer = {

  689.     .name           = "ffm",

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

  691.     .priv_data_size = sizeof(FFMContext),

  692.     .read_probe     = ffm_probe,

  693.     .read_header    = ffm_read_header,

  694.     .read_packet    = ffm_read_packet,

  695.     .read_close     = ffm_close,

  696.     .read_seek      = ffm_seek,

  697. };