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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.             if (ffm->packet_size < FFM_HEADER_SIZE + fill_size || frame_offset < 0) {

  114.                 return -1;

  115.             }

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

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

  118.                handle it specifically */

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

  120.                 if (!frame_offset) {

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

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

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

  124.                         seekback = FFMAX(seekback, 0);

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

  126.                         goto retry_read;

  127.                     }

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

  129.                     return 0;

  130.                 }

  131.                 ffm->first_packet = 0;

  132.                 if ((frame_offset & 0x7fff) < FFM_HEADER_SIZE) {

  133.                     ffm->packet_end = ffm->packet_ptr;

  134.                     return -1;

  135.                 }

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

  137.                 if (!header)

  138.                     break;

  139.             } else {

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

  141.             }

  142.             goto redo;

  143.         }

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

  145.         buf += len;

  146.         ffm->packet_ptr += len;

  147.         size -= len;

  148.         header = 0;

  149.     }

  150.     return size1 - size;

  151. }

  152. 

  153. /* ensure that acutal seeking happens between FFM_PACKET_SIZE

  154.    and file_size - FFM_PACKET_SIZE */

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

  156. {

  157.     FFMContext *ffm = s->priv_data;

  158.     AVIOContext *pb = s->pb;

  159.     int64_t pos;

  160. 

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

  162.     pos = FFMAX(pos, FFM_PACKET_SIZE);

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

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

  165. }

  166. 

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

  168. {

  169.     AVIOContext *pb = s->pb;

  170.     int64_t dts;

  171. 

  172.     ffm_seek1(s, pos);

  173.     avio_skip(pb, 4);

  174.     dts = avio_rb64(pb);

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

  176.     return dts;

  177. }

  178. 

  179. static void adjust_write_index(AVFormatContext *s)

  180. {

  181.     FFMContext *ffm = s->priv_data;

  182.     AVIOContext *pb = s->pb;

  183.     int64_t pts;

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

  185.     int64_t pos_min, pos_max;

  186.     int64_t pts_start;

  187.     int64_t ptr = avio_tell(pb);

  188. 

  189. 

  190.     pos_min = 0;

  191.     pos_max = ffm->file_size - 2 * 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.         goto end;

  199. 

  200.     ffm->write_index = FFM_PACKET_SIZE;

  201. 

  202.     pts_start = get_dts(s, pos_min);

  203. 

  204.     pts = get_dts(s, pos_max);

  205. 

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

  207.         while (1) {

  208.             int64_t newpos;

  209.             int64_t newpts;

  210. 

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

  212. 

  213.             if (newpos == pos_min)

  214.                 break;

  215. 

  216.             newpts = get_dts(s, newpos);

  217. 

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

  219.                 pos_max = newpos;

  220.                 pts = newpts;

  221.             } else {

  222.                 pos_min = newpos;

  223.             }

  224.         }

  225.         ffm->write_index += pos_max;

  226.     }

  227. 

  228.  end:

  229.     avio_seek(pb, ptr, SEEK_SET);

  230. }

  231. 

  232. 

  233. static int ffm_close(AVFormatContext *s)

  234. {

  235.     int i;

  236. 

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

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

  239. 

  240.     return 0;

  241. }

  242. 

  243. static int ffm2_read_header(AVFormatContext *s)

  244. {

  245.     FFMContext *ffm = s->priv_data;

  246.     AVStream *st;

  247.     AVIOContext *pb = s->pb;

  248.     AVCodecContext *codec;

  249.     const AVCodecDescriptor *codec_desc;

  250.     int ret;

  251. 

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

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

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

  255.                ffm->packet_size, FFM_PACKET_SIZE);

  256.         ret = AVERROR_INVALIDDATA;

  257.         goto fail;

  258.     }

  259. 

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

  261.     /* get also filesize */

  262.     if (pb->seekable) {

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

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

  265.             adjust_write_index(s);

  266.     } else {

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

  268.     }

  269. 

  270.     while(!avio_feof(pb)) {

  271.         unsigned id = avio_rb32(pb);

  272.         unsigned size = avio_rb32(pb);

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

  274.         char rc_eq_buf[128];

  275. 

  276.         if(!id)

  277.             break;

  278. 

  279.         switch(id) {

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

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

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

  283.             break;

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

  285.             st = avformat_new_stream(s, NULL);

  286.             if (!st) {

  287.                 ret = AVERROR(ENOMEM);

  288.                 goto fail;

  289.             }

  290. 

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

  292. 

  293.             codec = st->codec;

  294.             /* generic info */

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

  296.             codec_desc = avcodec_descriptor_get(codec->codec_id);

  297.             if (!codec_desc) {

  298.                 av_log(s, AV_LOG_ERROR, "Invalid codec id: %d\n", codec->codec_id);

  299.                 codec->codec_id = AV_CODEC_ID_NONE;

  300.                 goto fail;

  301.             }

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

  303.             if (codec->codec_type != codec_desc->type) {

  304.                 av_log(s, AV_LOG_ERROR, "Codec type mismatch: expected %d, found %d\n",

  305.                        codec_desc->type, codec->codec_type);

  306.                 codec->codec_id = AV_CODEC_ID_NONE;

  307.                 codec->codec_type = AVMEDIA_TYPE_UNKNOWN;

  308.                 goto fail;

  309.             }

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

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

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

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

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

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

  316.                     return AVERROR(ENOMEM);

  317.             }

  318.             avio_seek(pb, next, SEEK_SET);

  319.             id = avio_rb32(pb);

  320.             size = avio_rb32(pb);

  321.             next = avio_tell(pb) + size;

  322.             switch(id) {

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

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

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

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

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

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

  329.                     ret = AVERROR_INVALIDDATA;

  330.                     goto fail;

  331.                 }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  374.                 break;

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

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

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

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

  379.                 break;

  380.             }

  381.             break;

  382.         }

  383.         avio_seek(pb, next, SEEK_SET);

  384.     }

  385. 

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

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

  388.         avio_r8(pb);

  389. 

  390.     /* init packet demux */

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

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

  393.     ffm->frame_offset = 0;

  394.     ffm->dts = 0;

  395.     ffm->read_state = READ_HEADER;

  396.     ffm->first_packet = 1;

  397.     return 0;

  398.  fail:

  399.     ffm_close(s);

  400.     return ret;

  401. }

  402. 

  403. static int ffm_read_header(AVFormatContext *s)

  404. {

  405.     FFMContext *ffm = s->priv_data;

  406.     AVStream *st;

  407.     AVIOContext *pb = s->pb;

  408.     AVCodecContext *codec;

  409.     const AVCodecDescriptor *codec_desc;

  410.     int i, nb_streams;

  411.     uint32_t tag;

  412. 

  413.     /* header */

  414.     tag = avio_rl32(pb);

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

  416.         return ffm2_read_header(s);

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

  418.         goto fail;

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

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

  421.         goto fail;

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

  423.     /* get also filesize */

  424.     if (pb->seekable) {

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

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

  427.             adjust_write_index(s);

  428.     } else {

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

  430.     }

  431. 

  432.     nb_streams = avio_rb32(pb);

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

  434.     /* read each stream */

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

  436.         char rc_eq_buf[128];

  437. 

  438.         st = avformat_new_stream(s, NULL);

  439.         if (!st)

  440.             goto fail;

  441. 

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

  443. 

  444.         codec = st->codec;

  445.         /* generic info */

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

  447.         codec_desc = avcodec_descriptor_get(codec->codec_id);

  448.         if (!codec_desc) {

  449.             av_log(s, AV_LOG_ERROR, "Invalid codec id: %d\n", codec->codec_id);

  450.             codec->codec_id = AV_CODEC_ID_NONE;

  451.             goto fail;

  452.         }

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

  454.         if (codec->codec_type != codec_desc->type) {

  455.             av_log(s, AV_LOG_ERROR, "Codec type mismatch: expected %d, found %d\n",

  456.                    codec_desc->type, codec->codec_type);

  457.             codec->codec_id = AV_CODEC_ID_NONE;

  458.             codec->codec_type = AVMEDIA_TYPE_UNKNOWN;

  459.             goto fail;

  460.         }

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

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

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

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

  465.         /* specific info */

  466.         switch(codec->codec_type) {

  467.         case AVMEDIA_TYPE_VIDEO:

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

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

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

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

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

  473.                 goto fail;

  474.             }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  517.             break;

  518.         case AVMEDIA_TYPE_AUDIO:

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

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

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

  522.             break;

  523.         default:

  524.             goto fail;

  525.         }

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

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

  528.                 return AVERROR(ENOMEM);

  529.         }

  530.     }

  531. 

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

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

  534.         avio_r8(pb);

  535. 

  536.     /* init packet demux */

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

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

  539.     ffm->frame_offset = 0;

  540.     ffm->dts = 0;

  541.     ffm->read_state = READ_HEADER;

  542.     ffm->first_packet = 1;

  543.     return 0;

  544.  fail:

  545.     ffm_close(s);

  546.     return -1;

  547. }

  548. 

  549. /* return < 0 if eof */

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

  551. {

  552.     int size;

  553.     FFMContext *ffm = s->priv_data;

  554.     int duration, ret;

  555. 

  556.     switch(ffm->read_state) {

  557.     case READ_HEADER:

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

  559.             return ret;

  560. 

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

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

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

  564.             FRAME_HEADER_SIZE)

  565.             return -1;

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

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

  568.                 return -1;

  569.         ffm->read_state = READ_DATA;

  570.         /* fall through */

  571.     case READ_DATA:

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

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

  574.             return ret;

  575. 

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

  577. 

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

  579.             return AVERROR(ENOMEM);

  580.         }

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

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

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

  584.             av_free_packet(pkt);

  585.             ffm->read_state = READ_HEADER;

  586.             return -1;

  587.         }

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

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

  590.             pkt->flags |= AV_PKT_FLAG_KEY;

  591. 

  592.         ffm->read_state = READ_HEADER;

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

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

  595.             av_free_packet(pkt);

  596.             return -1;

  597.         }

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

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

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

  601.         else

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

  603.         pkt->duration = duration;

  604.         break;

  605.     }

  606.     return 0;

  607. }

  608. 

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

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

  611.    approximative */

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

  613. {

  614.     FFMContext *ffm = s->priv_data;

  615.     int64_t pos_min, pos_max, pos;

  616.     int64_t pts_min, pts_max, pts;

  617.     double pos1;

  618. 

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

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

  621.        dichotomy in typical cases) */

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

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

  624.             pos_min = FFM_PACKET_SIZE;

  625.             pos_max = ffm->write_index - FFM_PACKET_SIZE;

  626.         } else {

  627.             pos_min = ffm->write_index;

  628.             pos_max = ffm->file_size - FFM_PACKET_SIZE;

  629.         }

  630.     } else {

  631.         pos_min = FFM_PACKET_SIZE;

  632.         pos_max = ffm->file_size - FFM_PACKET_SIZE;

  633.     }

  634.     while (pos_min <= pos_max) {

  635.         pts_min = get_dts(s, pos_min);

  636.         pts_max = get_dts(s, pos_max);

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

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

  639.             goto found;

  640.         }

  641.         /* linear interpolation */

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

  643.             (double)(pts_max - pts_min);

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

  645.         if (pos <= pos_min)

  646.             pos = pos_min;

  647.         else if (pos >= pos_max)

  648.             pos = pos_max;

  649.         pts = get_dts(s, pos);

  650.         /* check if we are lucky */

  651.         if (pts == wanted_pts) {

  652.             goto found;

  653.         } else if (pts > wanted_pts) {

  654.             pos_max = pos - FFM_PACKET_SIZE;

  655.         } else {

  656.             pos_min = pos + FFM_PACKET_SIZE;

  657.         }

  658.     }

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

  660. 

  661.  found:

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

  663.         return -1;

  664. 

  665.     /* reset read state */

  666.     ffm->read_state = READ_HEADER;

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

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

  669.     ffm->first_packet = 1;

  670. 

  671.     return 0;

  672. }

  673. 

  674. static int ffm_probe(AVProbeData *p)

  675. {

  676.     if (

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

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

  679.         return AVPROBE_SCORE_MAX + 1;

  680.     return 0;

  681. }

  682. 

  683. AVInputFormat ff_ffm_demuxer = {

  684.     .name           = "ffm",

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

  686.     .priv_data_size = sizeof(FFMContext),

  687.     .read_probe     = ffm_probe,

  688.     .read_header    = ffm_read_header,

  689.     .read_packet    = ffm_read_packet,

  690.     .read_close     = ffm_close,

  691.     .read_seek      = ffm_seek,

  692. };