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  1. /*
  2.  * DVB subtitle parser for FFmpeg
  3.  * Copyright (c) 2005 Ian Caulfield
  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. #include "avcodec.h"
  22. #include "get_bits.h"
  23.  
  24. /* Parser (mostly) copied from dvdsub.c */
  25.  
  26. #define PARSE_BUF_SIZE  (65536)
  27.  
  28.  
  29. /* parser definition */
  30. typedef struct DVBSubParseContext {
  31.     uint8_t *packet_buf;
  32.     int packet_start;
  33.     int packet_index;
  34.     int in_packet;
  35. } DVBSubParseContext;
  36.  
  37. static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
  38. {
  39.     DVBSubParseContext *pc = s->priv_data;
  40.     pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
  41.  
  42.     return 0;
  43. }
  44.  
  45. static int dvbsub_parse(AVCodecParserContext *s,
  46.                         AVCodecContext *avctx,
  47.                         const uint8_t **poutbuf, int *poutbuf_size,
  48.                         const uint8_t *buf, int buf_size)
  49. {
  50.     DVBSubParseContext *pc = s->priv_data;
  51.     uint8_t *p, *p_end;
  52.     int i, len, buf_pos = 0;
  53.  
  54.     av_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
  55.             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
  56.  
  57.     for (i=0; i < buf_size; i++)
  58.     {
  59.         av_dlog(avctx, "%02x ", buf[i]);
  60.         if (i % 16 == 15)
  61.             av_dlog(avctx, "\n");
  62.     }
  63.  
  64.     if (i % 16 != 0)
  65.         av_dlog(avctx, "\n");
  66.  
  67.     *poutbuf = NULL;
  68.     *poutbuf_size = 0;
  69.  
  70.     s->fetch_timestamp = 1;
  71.  
  72.     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
  73.     {
  74.         if (pc->packet_index != pc->packet_start)
  75.         {
  76.             av_dlog(avctx, "Discarding %d bytes\n",
  77.                     pc->packet_index - pc->packet_start);
  78.         }
  79.  
  80.         pc->packet_start = 0;
  81.         pc->packet_index = 0;
  82.  
  83.         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
  84.             av_dlog(avctx, "Bad packet header\n");
  85.             return -1;
  86.         }
  87.  
  88.         buf_pos = 2;
  89.  
  90.         pc->in_packet = 1;
  91.     } else {
  92.         if (pc->packet_start != 0)
  93.         {
  94.             if (pc->packet_index != pc->packet_start)
  95.             {
  96.                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
  97.                             pc->packet_index - pc->packet_start);
  98.  
  99.                 pc->packet_index -= pc->packet_start;
  100.                 pc->packet_start = 0;
  101.             } else {
  102.                 pc->packet_start = 0;
  103.                 pc->packet_index = 0;
  104.             }
  105.         }
  106.     }
  107.  
  108.     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
  109.         return -1;
  110.  
  111. /* if not currently in a packet, discard data */
  112.     if (pc->in_packet == 0)
  113.         return buf_size;
  114.  
  115.     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
  116.     pc->packet_index += buf_size - buf_pos;
  117.  
  118.     p = pc->packet_buf;
  119.     p_end = pc->packet_buf + pc->packet_index;
  120.  
  121.     while (p < p_end)
  122.     {
  123.         if (*p == 0x0f)
  124.         {
  125.             if (p + 6 <= p_end)
  126.             {
  127.                 len = AV_RB16(p + 4);
  128.  
  129.                 if (p + len + 6 <= p_end)
  130.                 {
  131.                     *poutbuf_size += len + 6;
  132.  
  133.                     p += len + 6;
  134.                 } else
  135.                     break;
  136.             } else
  137.                 break;
  138.         } else if (*p == 0xff) {
  139.             if (p + 1 < p_end)
  140.             {
  141.                 av_dlog(avctx, "Junk at end of packet\n");
  142.             }
  143.             pc->packet_index = p - pc->packet_buf;
  144.             pc->in_packet = 0;
  145.             break;
  146.         } else {
  147.             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
  148.  
  149.             pc->packet_index = p - pc->packet_buf;
  150.             pc->in_packet = 0;
  151.             break;
  152.         }
  153.     }
  154.  
  155.     if (*poutbuf_size > 0)
  156.     {
  157.         *poutbuf = pc->packet_buf;
  158.         pc->packet_start = *poutbuf_size;
  159.     }
  160.  
  161.     if (s->pts == AV_NOPTS_VALUE)
  162.         s->pts = s->last_pts;
  163.  
  164.     return buf_size;
  165. }
  166.  
  167. static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
  168. {
  169.     DVBSubParseContext *pc = s->priv_data;
  170.     av_freep(&pc->packet_buf);
  171. }
  172.  
  173. AVCodecParser ff_dvbsub_parser = {
  174.     .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },
  175.     .priv_data_size = sizeof(DVBSubParseContext),
  176.     .parser_init    = dvbsub_parse_init,
  177.     .parser_parse   = dvbsub_parse,
  178.     .parser_close   = dvbsub_parse_close,
  179. };
  180.