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
  22 #include <inttypes.h>
  23 #include <string.h>
  24
  25 #include "libavutil/intreadwrite.h"
  26
  27 #include "avcodec.h"
  28 #include "internal.h"
  29
  30 /* Parser (mostly) copied from dvdsub.c */
  31
  32 #define PARSE_BUF_SIZE  (65536)
  33
  34
  35 /* parser definition */
  36 typedef struct DVBSubParseContext {
  37     uint8_t *packet_buf;
  38     int packet_start;
  39     int packet_index;
  40     int in_packet;
  41 } DVBSubParseContext;
  42
  43 static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
  44 {
  45     DVBSubParseContext *pc = s->priv_data;
  46     pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
  47
  48     return 0;
  49 }
  50
  51 static int dvbsub_parse(AVCodecParserContext *s,
  52                         AVCodecContext *avctx,
  53                         const uint8_t **poutbuf, int *poutbuf_size,
  54                         const uint8_t *buf, int buf_size)
  55 {
  56     DVBSubParseContext *pc = s->priv_data;
  57     uint8_t *p, *p_end;
  58     int i, len, buf_pos = 0;
  59
  60     ff_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
  61             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
  62
  63     for (i=0; i < buf_size; i++)
  64     {
  65         ff_dlog(avctx, "%02x ", buf[i]);
  66         if (i % 16 == 15)
  67             ff_dlog(avctx, "\n");
  68     }
  69
  70     if (i % 16 != 0)
  71         ff_dlog(avctx, "\n");
  72
  73     *poutbuf = NULL;
  74     *poutbuf_size = 0;
  75
  76     s->fetch_timestamp = 1;
  77
  78     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
  79     {
  80         if (pc->packet_index != pc->packet_start)
  81         {
  82             ff_dlog(avctx, "Discarding %d bytes\n",
  83                     pc->packet_index - pc->packet_start);
  84         }
  85
  86         pc->packet_start = 0;
  87         pc->packet_index = 0;
  88
  89         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
  90             ff_dlog(avctx, "Bad packet header\n");
  91             return -1;
  92         }
  93
  94         buf_pos = 2;
  95
  96         pc->in_packet = 1;
  97     } else {
  98         if (pc->packet_start != 0)
  99         {
 100             if (pc->packet_index != pc->packet_start)
 101             {
 102                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
 103                             pc->packet_index - pc->packet_start);
 104
 105                 pc->packet_index -= pc->packet_start;
 106                 pc->packet_start = 0;
 107             } else {
 108                 pc->packet_start = 0;
 109                 pc->packet_index = 0;
 110             }
 111         }
 112     }
 113
 114     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
 115         return -1;
 116
 117 /* if not currently in a packet, discard data */
 118     if (pc->in_packet == 0)
 119         return buf_size;
 120
 121     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
 122     pc->packet_index += buf_size - buf_pos;
 123
 124     p = pc->packet_buf;
 125     p_end = pc->packet_buf + pc->packet_index;
 126
 127     while (p < p_end)
 128     {
 129         if (*p == 0x0f)
 130         {
 131             if (6 <= p_end - p)
 132             {
 133                 len = AV_RB16(p + 4);
 134
 135                 if (len + 6 <= p_end - p)
 136                 {
 137                     *poutbuf_size += len + 6;
 138
 139                     p += len + 6;
 140                 } else
 141                     break;
 142             } else
 143                 break;
 144         } else if (*p == 0xff) {
 145             if (1 < p_end - p)
 146             {
 147                 ff_dlog(avctx, "Junk at end of packet\n");
 148             }
 149             pc->packet_index = p - pc->packet_buf;
 150             pc->in_packet = 0;
 151             break;
 152         } else {
 153             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
 154
 155             pc->packet_index = p - pc->packet_buf;
 156             pc->in_packet = 0;
 157             break;
 158         }
 159     }
 160
 161     if (*poutbuf_size > 0)
 162     {
 163         *poutbuf = pc->packet_buf;
 164         pc->packet_start = *poutbuf_size;
 165     }
 166
 167     if (s->pts == AV_NOPTS_VALUE)
 168         s->pts = s->last_pts;
 169
 170     return buf_size;
 171 }
 172
 173 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
 174 {
 175     DVBSubParseContext *pc = s->priv_data;
 176     av_freep(&pc->packet_buf);
 177 }
 178
 179 AVCodecParser ff_dvbsub_parser = {
 180     .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },
 181     .priv_data_size = sizeof(DVBSubParseContext),
 182     .parser_init    = dvbsub_parse_init,
 183     .parser_parse   = dvbsub_parse,
 184     .parser_close   = dvbsub_parse_close,
 185 };