git.sesse.net Git - ffmpeg/blob - 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 #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 };