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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. #include "internal.h"
  24.  
  25. /* Parser (mostly) copied from dvdsub.c */
  26.  
  27. #define PARSE_BUF_SIZE  (65536)
  28.  
  29.  
  30. /* parser definition */
  31. typedef struct DVBSubParseContext {
  32.     uint8_t *packet_buf;
  33.     int packet_start;
  34.     int packet_index;
  35.     int in_packet;
  36. } DVBSubParseContext;
  37.  
  38. static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
  39. {
  40.     DVBSubParseContext *pc = s->priv_data;
  41.     pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
  42.  
  43.     return 0;
  44. }
  45.  
  46. static int dvbsub_parse(AVCodecParserContext *s,
  47.                         AVCodecContext *avctx,
  48.                         const uint8_t **poutbuf, int *poutbuf_size,
  49.                         const uint8_t *buf, int buf_size)
  50. {
  51.     DVBSubParseContext *pc = s->priv_data;
  52.     uint8_t *p, *p_end;
  53.     int i, len, buf_pos = 0;
  54.  
  55.     ff_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
  56.             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
  57.  
  58.     for (i=0; i < buf_size; i++)
  59.     {
  60.         ff_dlog(avctx, "%02x ", buf[i]);
  61.         if (i % 16 == 15)
  62.             ff_dlog(avctx, "\n");
  63.     }
  64.  
  65.     if (i % 16 != 0)
  66.         ff_dlog(avctx, "\n");
  67.  
  68.     *poutbuf = NULL;
  69.     *poutbuf_size = 0;
  70.  
  71.     s->fetch_timestamp = 1;
  72.  
  73.     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
  74.     {
  75.         if (pc->packet_index != pc->packet_start)
  76.         {
  77.             ff_dlog(avctx, "Discarding %d bytes\n",
  78.                     pc->packet_index - pc->packet_start);
  79.         }
  80.  
  81.         pc->packet_start = 0;
  82.         pc->packet_index = 0;
  83.  
  84.         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
  85.             ff_dlog(avctx, "Bad packet header\n");
  86.             return -1;
  87.         }
  88.  
  89.         buf_pos = 2;
  90.  
  91.         pc->in_packet = 1;
  92.     } else {
  93.         if (pc->packet_start != 0)
  94.         {
  95.             if (pc->packet_index != pc->packet_start)
  96.             {
  97.                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
  98.                             pc->packet_index - pc->packet_start);
  99.  
  100.                 pc->packet_index -= pc->packet_start;
  101.                 pc->packet_start = 0;
  102.             } else {
  103.                 pc->packet_start = 0;
  104.                 pc->packet_index = 0;
  105.             }
  106.         }
  107.     }
  108.  
  109.     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
  110.         return -1;
  111.  
  112. /* if not currently in a packet, discard data */
  113.     if (pc->in_packet == 0)
  114.         return buf_size;
  115.  
  116.     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
  117.     pc->packet_index += buf_size - buf_pos;
  118.  
  119.     p = pc->packet_buf;
  120.     p_end = pc->packet_buf + pc->packet_index;
  121.  
  122.     while (p < p_end)
  123.     {
  124.         if (*p == 0x0f)
  125.         {
  126.             if (6 <= p_end - p)
  127.             {
  128.                 len = AV_RB16(p + 4);
  129.  
  130.                 if (len + 6 <= p_end - p)
  131.                 {
  132.                     *poutbuf_size += len + 6;
  133.  
  134.                     p += len + 6;
  135.                 } else
  136.                     break;
  137.             } else
  138.                 break;
  139.         } else if (*p == 0xff) {
  140.             if (1 < p_end - p)
  141.             {
  142.                 ff_dlog(avctx, "Junk at end of packet\n");
  143.             }
  144.             pc->packet_index = p - pc->packet_buf;
  145.             pc->in_packet = 0;
  146.             break;
  147.         } else {
  148.             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
  149.  
  150.             pc->packet_index = p - pc->packet_buf;
  151.             pc->in_packet = 0;
  152.             break;
  153.         }
  154.     }
  155.  
  156.     if (*poutbuf_size > 0)
  157.     {
  158.         *poutbuf = pc->packet_buf;
  159.         pc->packet_start = *poutbuf_size;
  160.     }
  161.  
  162.     if (s->pts == AV_NOPTS_VALUE)
  163.         s->pts = s->last_pts;
  164.  
  165.     return buf_size;
  166. }
  167.  
  168. static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
  169. {
  170.     DVBSubParseContext *pc = s->priv_data;
  171.     av_freep(&pc->packet_buf);
  172. }
  173.  
  174. AVCodecParser ff_dvbsub_parser = {
  175.     .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },
  176.     .priv_data_size = sizeof(DVBSubParseContext),
  177.     .parser_init    = dvbsub_parse_init,
  178.     .parser_parse   = dvbsub_parse,
  179.     .parser_close   = dvbsub_parse_close,
  180. };
  181.