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FFmpeg/libavformat/ffm.c

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  1. /*

  2.  * FFM (ffserver live feed) encoder and decoder

  3.  * Copyright (c) 2001 Fabrice Bellard.

  4.  *

  5.  * This library is free software; you can redistribute it and/or

  6.  * modify it under the terms of the GNU Lesser General Public

  7.  * License as published by the Free Software Foundation; either

  8.  * version 2 of the License, or (at your option) any later version.

  9.  *

  10.  * This library is distributed in the hope that it will be useful,

  11.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  12.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  13.  * Lesser General Public License for more details.

  14.  *

  15.  * You should have received a copy of the GNU Lesser General Public

  16.  * License along with this library; if not, write to the Free Software

  17.  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  18.  */

  19. #include "avformat.h"

  20. #include <unistd.h>

  21. 

  22. /* The FFM file is made of blocks of fixed size */

  23. #define FFM_HEADER_SIZE 14

  24. #define PACKET_ID       0x666d

  25. 

  26. /* each packet contains frames (which can span several packets */

  27. #define FRAME_HEADER_SIZE    8

  28. #define FLAG_KEY_FRAME       0x01

  29. 

  30. typedef struct FFMStream {

  31.     int64_t pts;

  32. } FFMStream;

  33. 

  34. enum {

  35.     READ_HEADER,

  36.     READ_DATA,

  37. };

  38. 

  39. typedef struct FFMContext {

  40.     /* only reading mode */

  41.     offset_t write_index, file_size;

  42.     int read_state;

  43.     uint8_t header[FRAME_HEADER_SIZE];

  44. 

  45.     /* read and write */

  46.     int first_packet; /* true if first packet, needed to set the discontinuity tag */

  47.     int packet_size;

  48.     int frame_offset;

  49.     int64_t pts;

  50.     uint8_t *packet_ptr, *packet_end;

  51.     uint8_t packet[FFM_PACKET_SIZE];

  52. } FFMContext;

  53. 

  54. static int64_t get_pts(AVFormatContext *s, offset_t pos);

  55. 

  56. /* disable pts hack for testing */

  57. int ffm_nopts = 0;

  58. 

  59. #ifdef CONFIG_ENCODERS

  60. static void flush_packet(AVFormatContext *s)

  61. {

  62.     FFMContext *ffm = s->priv_data;

  63.     int fill_size, h;

  64.     ByteIOContext *pb = &s->pb;

  65. 

  66.     fill_size = ffm->packet_end - ffm->packet_ptr;

  67.     memset(ffm->packet_ptr, 0, fill_size);

  68. 

  69.     if (url_ftell(pb) % ffm->packet_size) 

  70.         av_abort();

  71. 

  72.     /* put header */

  73.     put_be16(pb, PACKET_ID);

  74.     put_be16(pb, fill_size);

  75.     put_be64(pb, ffm->pts);

  76.     h = ffm->frame_offset;

  77.     if (ffm->first_packet)

  78.         h |= 0x8000;

  79.     put_be16(pb, h);

  80.     put_buffer(pb, ffm->packet, ffm->packet_end - ffm->packet);

  81.     put_flush_packet(pb);

  82. 

  83.     /* prepare next packet */

  84.     ffm->frame_offset = 0; /* no key frame */

  85.     ffm->pts = 0; /* no pts */

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

  87.     ffm->first_packet = 0;

  88. }

  89. 

  90. /* 'first' is true if first data of a frame */

  91. static void ffm_write_data(AVFormatContext *s,

  92.                            const uint8_t *buf, int size,

  93.                            int64_t pts, int first)

  94. {

  95.     FFMContext *ffm = s->priv_data;

  96.     int len;

  97. 

  98.     if (first && ffm->frame_offset == 0)

  99.         ffm->frame_offset = ffm->packet_ptr - ffm->packet + FFM_HEADER_SIZE;

  100.     if (first && ffm->pts == 0)

  101.         ffm->pts = pts;

  102. 

  103.     /* write as many packets as needed */

  104.     while (size > 0) {

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

  106.         if (len > size)

  107.             len = size;

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

  109. 

  110.         ffm->packet_ptr += len;

  111.         buf += len;

  112.         size -= len;

  113.         if (ffm->packet_ptr >= ffm->packet_end) {

  114.             /* special case : no pts in packet : we leave the current one */

  115.             if (ffm->pts == 0)

  116.                 ffm->pts = pts;

  117. 

  118.             flush_packet(s);

  119.         }

  120.     }

  121. }

  122. 

  123. static int ffm_write_header(AVFormatContext *s)

  124. {

  125.     FFMContext *ffm = s->priv_data;

  126.     AVStream *st;

  127.     FFMStream *fst;

  128.     ByteIOContext *pb = &s->pb;

  129.     AVCodecContext *codec;

  130.     int bit_rate, i;

  131. 

  132.     ffm->packet_size = FFM_PACKET_SIZE;

  133. 

  134.     /* header */

  135.     put_tag(pb, "FFM1");

  136.     put_be32(pb, ffm->packet_size);

  137.     /* XXX: store write position in other file ? */

  138.     put_be64(pb, ffm->packet_size); /* current write position */

  139. 

  140.     put_be32(pb, s->nb_streams);

  141.     bit_rate = 0;

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

  143.         st = s->streams[i];

  144.         bit_rate += st->codec.bit_rate;

  145.     }

  146.     put_be32(pb, bit_rate);

  147. 

  148.     /* list of streams */

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

  150.         st = s->streams[i];

  151.         fst = av_mallocz(sizeof(FFMStream));

  152.         if (!fst)

  153.             goto fail;

  154.         av_set_pts_info(st, 64, 1, 1000000);

  155.         st->priv_data = fst;

  156. 

  157.         codec = &st->codec;

  158.         /* generic info */

  159.         put_be32(pb, codec->codec_id);

  160.         put_byte(pb, codec->codec_type);

  161.         put_be32(pb, codec->bit_rate);

  162. 	put_be32(pb, st->quality);

  163.         put_be32(pb, codec->flags);

  164.         put_be32(pb, codec->flags2);

  165.         put_be32(pb, codec->debug);

  166.         /* specific info */

  167.         switch(codec->codec_type) {

  168.         case CODEC_TYPE_VIDEO:

  169.             put_be32(pb, codec->time_base.num);

  170.             put_be32(pb, codec->time_base.den);

  171.             put_be16(pb, codec->width);

  172.             put_be16(pb, codec->height);

  173.             put_be16(pb, codec->gop_size);

  174.             put_be32(pb, codec->pix_fmt);

  175.             put_byte(pb, codec->qmin);

  176.             put_byte(pb, codec->qmax);

  177.             put_byte(pb, codec->max_qdiff);

  178.             put_be16(pb, (int) (codec->qcompress * 10000.0));

  179.             put_be16(pb, (int) (codec->qblur * 10000.0));

  180.             put_be32(pb, codec->bit_rate_tolerance);

  181.             put_strz(pb, codec->rc_eq);

  182.             put_be32(pb, codec->rc_max_rate);

  183.             put_be32(pb, codec->rc_min_rate);

  184.             put_be32(pb, codec->rc_buffer_size);

  185.             put_be64_double(pb, codec->i_quant_factor);

  186.             put_be64_double(pb, codec->b_quant_factor);

  187.             put_be64_double(pb, codec->i_quant_offset);

  188.             put_be64_double(pb, codec->b_quant_offset);

  189.             put_be32(pb, codec->dct_algo);

  190.             put_be32(pb, codec->strict_std_compliance);

  191.             put_be32(pb, codec->max_b_frames);

  192.             put_be32(pb, codec->luma_elim_threshold);

  193.             put_be32(pb, codec->chroma_elim_threshold);

  194.             put_be32(pb, codec->mpeg_quant);

  195.             put_be32(pb, codec->intra_dc_precision);

  196.             put_be32(pb, codec->me_method);

  197.             put_be32(pb, codec->mb_decision);

  198.             put_be32(pb, codec->nsse_weight);

  199.             put_be32(pb, codec->frame_skip_cmp);

  200.             put_be64_double(pb, codec->rc_buffer_aggressivity);

  201.             break;

  202.         case CODEC_TYPE_AUDIO:

  203.             put_be32(pb, codec->sample_rate);

  204.             put_le16(pb, codec->channels);

  205.             put_le16(pb, codec->frame_size);

  206.             break;

  207.         default:

  208.             return -1;

  209.         }

  210.         /* hack to have real time */

  211.         if (ffm_nopts)

  212.             fst->pts = 0;

  213.         else

  214.             fst->pts = av_gettime();

  215.     }

  216. 

  217.     /* flush until end of block reached */

  218.     while ((url_ftell(pb) % ffm->packet_size) != 0)

  219.         put_byte(pb, 0);

  220. 

  221.     put_flush_packet(pb);

  222. 

  223.     /* init packet mux */

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

  225.     ffm->packet_end = ffm->packet + ffm->packet_size - FFM_HEADER_SIZE;

  226.     assert(ffm->packet_end >= ffm->packet);

  227.     ffm->frame_offset = 0;

  228.     ffm->pts = 0;

  229.     ffm->first_packet = 1;

  230. 

  231.     return 0;

  232.  fail:

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

  234.         st = s->streams[i];

  235.         av_freep(&st->priv_data);

  236.     }

  237.     return -1;

  238. }

  239. 

  240. static int ffm_write_packet(AVFormatContext *s, AVPacket *pkt)

  241. {

  242.     AVStream *st = s->streams[pkt->stream_index];

  243.     FFMStream *fst = st->priv_data;

  244.     int64_t pts;

  245.     uint8_t header[FRAME_HEADER_SIZE];

  246.     int duration;

  247.     int size= pkt->size;

  248. 

  249.     //XXX/FIXME use duration from pkt

  250.     if (st->codec.codec_type == CODEC_TYPE_AUDIO) {

  251.         duration = ((float)st->codec.frame_size / st->codec.sample_rate * 1000000.0);

  252.     } else {

  253.         duration = (1000000.0 * st->codec.time_base.num / (float)st->codec.time_base.den);

  254.     }

  255. 

  256.     pts = fst->pts;

  257.     /* packet size & key_frame */

  258.     header[0] = pkt->stream_index;

  259.     header[1] = 0;

  260.     if (pkt->flags & PKT_FLAG_KEY)

  261.         header[1] |= FLAG_KEY_FRAME;

  262.     header[2] = (size >> 16) & 0xff;

  263.     header[3] = (size >> 8) & 0xff;

  264.     header[4] = size & 0xff;

  265.     header[5] = (duration >> 16) & 0xff;

  266.     header[6] = (duration >> 8) & 0xff;

  267.     header[7] = duration & 0xff;

  268.     ffm_write_data(s, header, FRAME_HEADER_SIZE, pts, 1);

  269.     ffm_write_data(s, pkt->data, size, pts, 0);

  270. 

  271.     fst->pts += duration;

  272.     return 0;

  273. }

  274. 

  275. static int ffm_write_trailer(AVFormatContext *s)

  276. {

  277.     ByteIOContext *pb = &s->pb;

  278.     FFMContext *ffm = s->priv_data;

  279. 

  280.     /* flush packets */

  281.     if (ffm->packet_ptr > ffm->packet)

  282.         flush_packet(s);

  283. 

  284.     put_flush_packet(pb);

  285. 

  286.     if (!url_is_streamed(pb)) {

  287.         int64_t size;

  288.         /* update the write offset */

  289.         size = url_ftell(pb);

  290.         url_fseek(pb, 8, SEEK_SET);

  291.         put_be64(pb, size);

  292.         put_flush_packet(pb);

  293.     }

  294. 

  295.     return 0;

  296. }

  297. #endif //CONFIG_ENCODERS

  298. 

  299. /* ffm demux */

  300. 

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

  302. {

  303.     FFMContext *ffm = s->priv_data;

  304.     offset_t pos, avail_size;

  305.     int len;

  306. 

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

  308.     if (!ffm_nopts) {

  309.         /* XXX: I don't understand this test, so I disabled it for testing */

  310.         if (size <= len)

  311.             return 1;

  312.     }

  313.     pos = url_ftell(&s->pb);

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

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

  316.         return 0;

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

  318.         avail_size = ffm->write_index - pos;

  319.     } else {

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

  321.     }

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

  323.     if (size <= avail_size)

  324.         return 1;

  325.     else

  326.         return 0;

  327. }

  328. 

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

  330. static int ffm_read_data(AVFormatContext *s,

  331.                          uint8_t *buf, int size, int first)

  332. {

  333.     FFMContext *ffm = s->priv_data;

  334.     ByteIOContext *pb = &s->pb;

  335.     int len, fill_size, size1, frame_offset;

  336. 

  337.     size1 = size;

  338.     while (size > 0) {

  339.     redo:

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

  341.         if (len > size)

  342.             len = size;

  343.         if (len == 0) {

  344.             if (url_ftell(pb) == ffm->file_size)

  345.                 url_fseek(pb, ffm->packet_size, SEEK_SET);

  346.     retry_read:

  347.             get_be16(pb); /* PACKET_ID */

  348.             fill_size = get_be16(pb);

  349.             ffm->pts = get_be64(pb);

  350.             frame_offset = get_be16(pb);

  351.             get_buffer(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);

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

  353.             if (ffm->packet_end < ffm->packet)

  354.                 return -1;

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

  356.                handle it specifically */

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

  358.                 if (!frame_offset) {

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

  360.                     if (url_ftell(pb) >= ffm->packet_size * 3) {

  361.                         url_fseek(pb, -ffm->packet_size * 2, SEEK_CUR);

  362.                         goto retry_read;

  363.                     }

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

  365.                     return 0;

  366.                 }

  367.                 ffm->first_packet = 0;

  368.                 if ((frame_offset & 0x7ffff) < FFM_HEADER_SIZE)

  369.                     return -1;

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

  371.                 if (!first)

  372.                     break;

  373.             } else {

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

  375.             }

  376.             goto redo;

  377.         }

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

  379.         buf += len;

  380.         ffm->packet_ptr += len;

  381.         size -= len;

  382.         first = 0;

  383.     }

  384.     return size1 - size;

  385. }

  386. 

  387. 

  388. static void adjust_write_index(AVFormatContext *s)

  389. {

  390.     FFMContext *ffm = s->priv_data;

  391.     ByteIOContext *pb = &s->pb;

  392.     int64_t pts;

  393.     //offset_t orig_write_index = ffm->write_index;

  394.     offset_t pos_min, pos_max;

  395.     int64_t pts_start;

  396.     offset_t ptr = url_ftell(pb);

  397. 

  398. 

  399.     pos_min = 0;

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

  401. 

  402.     pts_start = get_pts(s, pos_min);

  403. 

  404.     pts = get_pts(s, pos_max);

  405. 

  406.     if (pts - 100000 > pts_start) 

  407.         goto end;

  408. 

  409.     ffm->write_index = FFM_PACKET_SIZE;

  410. 

  411.     pts_start = get_pts(s, pos_min);

  412. 

  413.     pts = get_pts(s, pos_max);

  414. 

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

  416.         while (1) {

  417.             offset_t newpos;

  418.             int64_t newpts;

  419. 

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

  421. 

  422.             if (newpos == pos_min)

  423.                 break;

  424. 

  425.             newpts = get_pts(s, newpos);

  426. 

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

  428.                 pos_max = newpos;

  429.                 pts = newpts;

  430.             } else {

  431.                 pos_min = newpos;

  432.             }

  433.         }

  434.         ffm->write_index += pos_max;

  435.     }

  436. 

  437.     //printf("Adjusted write index from %lld to %lld: pts=%0.6f\n", orig_write_index, ffm->write_index, pts / 1000000.);

  438.     //printf("pts range %0.6f - %0.6f\n", get_pts(s, 0) / 1000000. , get_pts(s, ffm->file_size - 2 * FFM_PACKET_SIZE) / 1000000. );

  439. 

  440.  end:

  441.     url_fseek(pb, ptr, SEEK_SET);

  442. }

  443. 

  444. 

  445. static int ffm_read_header(AVFormatContext *s, AVFormatParameters *ap)

  446. {

  447.     FFMContext *ffm = s->priv_data;

  448.     AVStream *st;

  449.     FFMStream *fst;

  450.     ByteIOContext *pb = &s->pb;

  451.     AVCodecContext *codec;

  452.     int i, nb_streams;

  453.     uint32_t tag;

  454. 

  455.     /* header */

  456.     tag = get_le32(pb);

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

  458.         goto fail;

  459.     ffm->packet_size = get_be32(pb);

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

  461.         goto fail;

  462.     ffm->write_index = get_be64(pb);

  463.     /* get also filesize */

  464.     if (!url_is_streamed(pb)) {

  465.         ffm->file_size = url_fsize(pb);

  466.         adjust_write_index(s);

  467.     } else {

  468.         ffm->file_size = (uint64_t_C(1) << 63) - 1;

  469.     }

  470. 

  471.     nb_streams = get_be32(pb);

  472.     get_be32(pb); /* total bitrate */

  473.     /* read each stream */

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

  475.         char rc_eq_buf[128];

  476. 

  477.         st = av_new_stream(s, 0);

  478.         if (!st)

  479.             goto fail;

  480.         fst = av_mallocz(sizeof(FFMStream));

  481.         if (!fst)

  482.             goto fail;

  483.             

  484.         av_set_pts_info(st, 64, 1, 1000000);

  485.             

  486.         st->priv_data = fst;

  487. 

  488.         codec = &st->codec;

  489.         /* generic info */

  490.         st->codec.codec_id = get_be32(pb);

  491.         st->codec.codec_type = get_byte(pb); /* codec_type */

  492.         codec->bit_rate = get_be32(pb);

  493. 	st->quality = get_be32(pb);

  494.         codec->flags = get_be32(pb);

  495.         codec->flags2 = get_be32(pb);

  496.         codec->debug = get_be32(pb);

  497.         /* specific info */

  498.         switch(codec->codec_type) {

  499.         case CODEC_TYPE_VIDEO:

  500.             codec->time_base.num = get_be32(pb);

  501.             codec->time_base.den = get_be32(pb);

  502.             codec->width = get_be16(pb);

  503.             codec->height = get_be16(pb);

  504.             codec->gop_size = get_be16(pb);

  505.             codec->pix_fmt = get_be32(pb);

  506.             codec->qmin = get_byte(pb);

  507.             codec->qmax = get_byte(pb);

  508.             codec->max_qdiff = get_byte(pb);

  509.             codec->qcompress = get_be16(pb) / 10000.0;

  510.             codec->qblur = get_be16(pb) / 10000.0;

  511.             codec->bit_rate_tolerance = get_be32(pb);

  512.             codec->rc_eq = av_strdup(get_strz(pb, rc_eq_buf, sizeof(rc_eq_buf)));

  513.             codec->rc_max_rate = get_be32(pb);

  514.             codec->rc_min_rate = get_be32(pb);

  515.             codec->rc_buffer_size = get_be32(pb);

  516.             codec->i_quant_factor = get_be64_double(pb);

  517.             codec->b_quant_factor = get_be64_double(pb);

  518.             codec->i_quant_offset = get_be64_double(pb);

  519.             codec->b_quant_offset = get_be64_double(pb);

  520.             codec->dct_algo = get_be32(pb);

  521.             codec->strict_std_compliance = get_be32(pb);

  522.             codec->max_b_frames = get_be32(pb);

  523.             codec->luma_elim_threshold = get_be32(pb);

  524.             codec->chroma_elim_threshold = get_be32(pb);

  525.             codec->mpeg_quant = get_be32(pb);

  526.             codec->intra_dc_precision = get_be32(pb);

  527.             codec->me_method = get_be32(pb);

  528.             codec->mb_decision = get_be32(pb);

  529.             codec->nsse_weight = get_be32(pb);

  530.             codec->frame_skip_cmp = get_be32(pb);

  531.             codec->rc_buffer_aggressivity = get_be64_double(pb);

  532.             break;

  533.         case CODEC_TYPE_AUDIO:

  534.             codec->sample_rate = get_be32(pb);

  535.             codec->channels = get_le16(pb);

  536.             codec->frame_size = get_le16(pb);

  537.             break;

  538.         default:

  539.             goto fail;

  540.         }

  541. 

  542.     }

  543. 

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

  545.     while ((url_ftell(pb) % ffm->packet_size) != 0)

  546.         get_byte(pb);

  547. 

  548.     /* init packet demux */

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

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

  551.     ffm->frame_offset = 0;

  552.     ffm->pts = 0;

  553.     ffm->read_state = READ_HEADER;

  554.     ffm->first_packet = 1;

  555.     return 0;

  556.  fail:

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

  558.         st = s->streams[i];

  559.         if (st) {

  560.             av_freep(&st->priv_data);

  561.             av_free(st);

  562.         }

  563.     }

  564.     return -1;

  565. }

  566. 

  567. /* return < 0 if eof */

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

  569. {

  570.     int size;

  571.     FFMContext *ffm = s->priv_data;

  572.     int duration;

  573. 

  574.     switch(ffm->read_state) {

  575.     case READ_HEADER:

  576.         if (!ffm_is_avail_data(s, FRAME_HEADER_SIZE)) {

  577.             return -EAGAIN;

  578.         }

  579. #if 0

  580.         printf("pos=%08Lx spos=%Lx, write_index=%Lx size=%Lx\n",

  581.                url_ftell(&s->pb), s->pb.pos, ffm->write_index, ffm->file_size);

  582. #endif

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

  584.             FRAME_HEADER_SIZE)

  585.             return -EAGAIN;

  586. #if 0

  587.         {

  588.             int i;

  589.             for(i=0;i<FRAME_HEADER_SIZE;i++)

  590.                 printf("%02x ", ffm->header[i]);

  591.             printf("\n");

  592.         }

  593. #endif

  594.         ffm->read_state = READ_DATA;

  595.         /* fall thru */

  596.     case READ_DATA:

  597.         size = (ffm->header[2] << 16) | (ffm->header[3] << 8) | ffm->header[4];

  598.         if (!ffm_is_avail_data(s, size)) {

  599.             return -EAGAIN;

  600.         }

  601. 

  602.         duration = (ffm->header[5] << 16) | (ffm->header[6] << 8) | ffm->header[7];

  603. 

  604.         av_new_packet(pkt, size);

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

  606.         pkt->pos = url_ftell(&s->pb); 

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

  608.             pkt->flags |= PKT_FLAG_KEY;

  609. 

  610.         ffm->read_state = READ_HEADER;

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

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

  613.             av_free_packet(pkt);

  614.             return -EAGAIN;

  615.         }

  616.         pkt->pts = ffm->pts;

  617.         pkt->duration = duration;

  618.         break;

  619.     }

  620.     return 0;

  621. }

  622. 

  623. //#define DEBUG_SEEK

  624. 

  625. /* pos is between 0 and file_size - FFM_PACKET_SIZE. It is translated

  626.    by the write position inside this function */

  627. static void ffm_seek1(AVFormatContext *s, offset_t pos1)

  628. {

  629.     FFMContext *ffm = s->priv_data;

  630.     ByteIOContext *pb = &s->pb;

  631.     offset_t pos;

  632. 

  633.     pos = pos1 + ffm->write_index;

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

  635.         pos -= (ffm->file_size - FFM_PACKET_SIZE);

  636. #ifdef DEBUG_SEEK

  637.     printf("seek to %Lx -> %Lx\n", pos1, pos);

  638. #endif

  639.     url_fseek(pb, pos, SEEK_SET);

  640. }

  641. 

  642. static int64_t get_pts(AVFormatContext *s, offset_t pos)

  643. {

  644.     ByteIOContext *pb = &s->pb;

  645.     int64_t pts;

  646. 

  647.     ffm_seek1(s, pos);

  648.     url_fskip(pb, 4);

  649.     pts = get_be64(pb);

  650. #ifdef DEBUG_SEEK

  651.     printf("pts=%0.6f\n", pts / 1000000.0);

  652. #endif

  653.     return pts;

  654. }

  655. 

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

  657.    positionned at or before pts. XXX: the following code is quite

  658.    approximative */

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

  660. {

  661.     FFMContext *ffm = s->priv_data;

  662.     offset_t pos_min, pos_max, pos;

  663.     int64_t pts_min, pts_max, pts;

  664.     double pos1;

  665. 

  666. #ifdef DEBUG_SEEK

  667.     printf("wanted_pts=%0.6f\n", wanted_pts / 1000000.0);

  668. #endif

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

  670.        dichotomy in typical cases) */

  671.     pos_min = 0;

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

  673.     while (pos_min <= pos_max) {

  674.         pts_min = get_pts(s, pos_min);

  675.         pts_max = get_pts(s, pos_max);

  676.         /* linear interpolation */

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

  678.             (double)(pts_max - pts_min);

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

  680.         if (pos <= pos_min)

  681.             pos = pos_min;

  682.         else if (pos >= pos_max)

  683.             pos = pos_max;

  684.         pts = get_pts(s, pos);

  685.         /* check if we are lucky */

  686.         if (pts == wanted_pts) {

  687.             goto found;

  688.         } else if (pts > wanted_pts) {

  689.             pos_max = pos - FFM_PACKET_SIZE;

  690.         } else {

  691.             pos_min = pos + FFM_PACKET_SIZE;

  692.         }

  693.     }

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

  695.     if (pos > 0)

  696.         pos -= FFM_PACKET_SIZE;

  697.  found:

  698.     ffm_seek1(s, pos);

  699.     return 0;

  700. }

  701. 

  702. offset_t ffm_read_write_index(int fd)

  703. {

  704.     uint8_t buf[8];

  705.     offset_t pos;

  706.     int i;

  707. 

  708.     lseek(fd, 8, SEEK_SET);

  709.     read(fd, buf, 8);

  710.     pos = 0;

  711.     for(i=0;i<8;i++)

  712.         pos |= (int64_t)buf[i] << (56 - i * 8);

  713.     return pos;

  714. }

  715. 

  716. void ffm_write_write_index(int fd, offset_t pos)

  717. {

  718.     uint8_t buf[8];

  719.     int i;

  720. 

  721.     for(i=0;i<8;i++)

  722.         buf[i] = (pos >> (56 - i * 8)) & 0xff;

  723.     lseek(fd, 8, SEEK_SET);

  724.     write(fd, buf, 8);

  725. }

  726. 

  727. void ffm_set_write_index(AVFormatContext *s, offset_t pos, offset_t file_size)

  728. {

  729.     FFMContext *ffm = s->priv_data;

  730.     ffm->write_index = pos;

  731.     ffm->file_size = file_size;

  732. }

  733. 

  734. static int ffm_read_close(AVFormatContext *s)

  735. {

  736.     AVStream *st;

  737.     int i;

  738. 

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

  740.         st = s->streams[i];

  741.         av_freep(&st->priv_data);

  742.     }

  743.     return 0;

  744. }

  745. 

  746. static int ffm_probe(AVProbeData *p)

  747. {

  748.     if (p->buf_size >= 4 &&

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

  750.         p->buf[3] == '1')

  751.         return AVPROBE_SCORE_MAX + 1;

  752.     return 0;

  753. }

  754. 

  755. static AVInputFormat ffm_iformat = {

  756.     "ffm",

  757.     "ffm format",

  758.     sizeof(FFMContext),

  759.     ffm_probe,

  760.     ffm_read_header,

  761.     ffm_read_packet,

  762.     ffm_read_close,

  763.     ffm_seek,

  764. };

  765. 

  766. #ifdef CONFIG_ENCODERS

  767. static AVOutputFormat ffm_oformat = {

  768.     "ffm",

  769.     "ffm format",

  770.     "",

  771.     "ffm",

  772.     sizeof(FFMContext),

  773.     /* not really used */

  774.     CODEC_ID_MP2,

  775.     CODEC_ID_MPEG1VIDEO,

  776.     ffm_write_header,

  777.     ffm_write_packet,

  778.     ffm_write_trailer,

  779. };

  780. #endif //CONFIG_ENCODERS

  781. 

  782. int ffm_init(void)

  783. {

  784.     av_register_input_format(&ffm_iformat);

  785. #ifdef CONFIG_ENCODERS

  786.     av_register_output_format(&ffm_oformat);

  787. #endif //CONFIG_ENCODERS

  788.     return 0;

  789. }