libavcodec/dvbsub_parser.c

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