libavcodec/dvbsub_parser.c

   1 /*
   2  * DVB subtitle parser for Libav
   3  * Copyright (c) 2005 Ian Caulfield
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 "dsputil.h"
  23 #include "get_bits.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     av_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         av_dlog(avctx, "%02x ", buf[i]);
  61         if (i % 16 == 15)
  62             av_dlog(avctx, "\n");
  63     }
  64
  65     if (i % 16 != 0)
  66         av_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             av_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             av_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 (p + 6 <= p_end)
 127             {
 128                 len = AV_RB16(p + 4);
 129
 130                 if (p + len + 6 <= p_end)
 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 (p + 1 < p_end)
 141             {
 142                 av_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 };