git.sesse.net Git - ffmpeg/blob - 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
  22 #include <inttypes.h>
  23 #include <string.h>
  24
  25 #include "libavutil/intreadwrite.h"
  26 #include "libavutil/mem.h"
  27
  28 #include "avcodec.h"
  29 #include "internal.h"
  30
  31 /* Parser (mostly) copied from dvdsub.c */
  32
  33 #define PARSE_BUF_SIZE  (65536)
  34
  35
  36 /* parser definition */
  37 typedef struct DVBSubParseContext {
  38     uint8_t *packet_buf;
  39     int packet_start;
  40     int packet_index;
  41     int in_packet;
  42 } DVBSubParseContext;
  43
  44 static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
  45 {
  46     DVBSubParseContext *pc = s->priv_data;
  47     pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
  48
  49     return 0;
  50 }
  51
  52 static int dvbsub_parse(AVCodecParserContext *s,
  53                         AVCodecContext *avctx,
  54                         const uint8_t **poutbuf, int *poutbuf_size,
  55                         const uint8_t *buf, int buf_size)
  56 {
  57     DVBSubParseContext *pc = s->priv_data;
  58     uint8_t *p, *p_end;
  59     int i, len, buf_pos = 0;
  60
  61     ff_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
  62             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
  63
  64     for (i=0; i < buf_size; i++)
  65     {
  66         ff_dlog(avctx, "%02x ", buf[i]);
  67         if (i % 16 == 15)
  68             ff_dlog(avctx, "\n");
  69     }
  70
  71     if (i % 16 != 0)
  72         ff_dlog(avctx, "\n");
  73
  74     *poutbuf = NULL;
  75     *poutbuf_size = 0;
  76
  77     s->fetch_timestamp = 1;
  78
  79     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
  80     {
  81         if (pc->packet_index != pc->packet_start)
  82         {
  83             ff_dlog(avctx, "Discarding %d bytes\n",
  84                     pc->packet_index - pc->packet_start);
  85         }
  86
  87         pc->packet_start = 0;
  88         pc->packet_index = 0;
  89
  90         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
  91             ff_dlog(avctx, "Bad packet header\n");
  92             return -1;
  93         }
  94
  95         buf_pos = 2;
  96
  97         pc->in_packet = 1;
  98     } else {
  99         if (pc->packet_start != 0)
 100         {
 101             if (pc->packet_index != pc->packet_start)
 102             {
 103                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
 104                             pc->packet_index - pc->packet_start);
 105
 106                 pc->packet_index -= pc->packet_start;
 107                 pc->packet_start = 0;
 108             } else {
 109                 pc->packet_start = 0;
 110                 pc->packet_index = 0;
 111             }
 112         }
 113     }
 114
 115     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
 116         return -1;
 117
 118 /* if not currently in a packet, discard data */
 119     if (pc->in_packet == 0)
 120         return buf_size;
 121
 122     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
 123     pc->packet_index += buf_size - buf_pos;
 124
 125     p = pc->packet_buf;
 126     p_end = pc->packet_buf + pc->packet_index;
 127
 128     while (p < p_end)
 129     {
 130         if (*p == 0x0f)
 131         {
 132             if (p + 6 <= p_end)
 133             {
 134                 len = AV_RB16(p + 4);
 135
 136                 if (p + len + 6 <= p_end)
 137                 {
 138                     *poutbuf_size += len + 6;
 139
 140                     p += len + 6;
 141                 } else
 142                     break;
 143             } else
 144                 break;
 145         } else if (*p == 0xff) {
 146             if (p + 1 < p_end)
 147             {
 148                 ff_dlog(avctx, "Junk at end of packet\n");
 149             }
 150             pc->packet_index = p - pc->packet_buf;
 151             pc->in_packet = 0;
 152             break;
 153         } else {
 154             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
 155
 156             pc->packet_index = p - pc->packet_buf;
 157             pc->in_packet = 0;
 158             break;
 159         }
 160     }
 161
 162     if (*poutbuf_size > 0)
 163     {
 164         *poutbuf = pc->packet_buf;
 165         pc->packet_start = *poutbuf_size;
 166     }
 167
 168     if (s->pts == AV_NOPTS_VALUE)
 169         s->pts = s->last_pts;
 170
 171     return buf_size;
 172 }
 173
 174 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
 175 {
 176     DVBSubParseContext *pc = s->priv_data;
 177     av_freep(&pc->packet_buf);
 178 }
 179
 180 AVCodecParser ff_dvbsub_parser = {
 181     .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },
 182     .priv_data_size = sizeof(DVBSubParseContext),
 183     .parser_init    = dvbsub_parse_init,
 184     .parser_parse   = dvbsub_parse,
 185     .parser_close   = dvbsub_parse_close,
 186 };