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 #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     int out_size = 0;
  61
  62     ff_dlog(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
  63             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
  64
  65     for (i=0; i < buf_size; i++)
  66     {
  67         ff_dlog(avctx, "%02x ", buf[i]);
  68         if (i % 16 == 15)
  69             ff_dlog(avctx, "\n");
  70     }
  71
  72     if (i % 16 != 0)
  73         ff_dlog(avctx, "\n");
  74
  75     *poutbuf      = buf;
  76     *poutbuf_size = buf_size;
  77
  78     s->fetch_timestamp = 1;
  79
  80     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
  81     {
  82         if (pc->packet_index != pc->packet_start)
  83         {
  84             ff_dlog(avctx, "Discarding %d bytes\n",
  85                     pc->packet_index - pc->packet_start);
  86         }
  87
  88         pc->packet_start = 0;
  89         pc->packet_index = 0;
  90
  91         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
  92             ff_dlog(avctx, "Bad packet header\n");
  93             return buf_size;
  94         }
  95
  96         buf_pos = 2;
  97
  98         pc->in_packet = 1;
  99     } else {
 100         if (pc->packet_start != 0)
 101         {
 102             if (pc->packet_index != pc->packet_start)
 103             {
 104                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
 105                             pc->packet_index - pc->packet_start);
 106
 107                 pc->packet_index -= pc->packet_start;
 108                 pc->packet_start = 0;
 109             } else {
 110                 pc->packet_start = 0;
 111                 pc->packet_index = 0;
 112             }
 113         }
 114     }
 115
 116     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
 117         return buf_size;
 118
 119 /* if not currently in a packet, pass data */
 120     if (pc->in_packet == 0)
 121         return buf_size;
 122
 123     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
 124     pc->packet_index += buf_size - buf_pos;
 125
 126     p = pc->packet_buf;
 127     p_end = pc->packet_buf + pc->packet_index;
 128
 129     while (p < p_end)
 130     {
 131         if (*p == 0x0f)
 132         {
 133             if (6 <= p_end - p)
 134             {
 135                 len = AV_RB16(p + 4);
 136
 137                 if (len + 6 <= p_end - p)
 138                 {
 139                     out_size += len + 6;
 140
 141                     p += len + 6;
 142                 } else
 143                     break;
 144             } else
 145                 break;
 146         } else if (*p == 0xff) {
 147             if (1 < p_end - p)
 148             {
 149                 ff_dlog(avctx, "Junk at end of packet\n");
 150             }
 151             pc->packet_index = p - pc->packet_buf;
 152             pc->in_packet = 0;
 153             break;
 154         } else {
 155             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
 156
 157             pc->packet_index = p - pc->packet_buf;
 158             pc->in_packet = 0;
 159             break;
 160         }
 161     }
 162
 163     if (out_size > 0)
 164     {
 165         *poutbuf = pc->packet_buf;
 166         *poutbuf_size = out_size;
 167         pc->packet_start = *poutbuf_size;
 168     }
 169
 170     if (s->pts == AV_NOPTS_VALUE)
 171         s->pts = s->last_pts;
 172
 173     return buf_size;
 174 }
 175
 176 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
 177 {
 178     DVBSubParseContext *pc = s->priv_data;
 179     av_freep(&pc->packet_buf);
 180 }
 181
 182 AVCodecParser ff_dvbsub_parser = {
 183     .codec_ids      = { AV_CODEC_ID_DVB_SUBTITLE },
 184     .priv_data_size = sizeof(DVBSubParseContext),
 185     .parser_init    = dvbsub_parse_init,
 186     .parser_parse   = dvbsub_parse,
 187     .parser_close   = dvbsub_parse_close,
 188 };