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 "dsputil.h"
  23 #include "get_bits.h"
  24
  25 //#define DEBUG
  26 //#define DEBUG_PACKET_CONTENTS
  27
  28 /* Parser (mostly) copied from dvdsub.c */
  29
  30 #define PARSE_BUF_SIZE  (65536)
  31
  32
  33 /* parser definition */
  34 typedef struct DVBSubParseContext {
  35     uint8_t *packet_buf;
  36     int packet_start;
  37     int packet_index;
  38     int in_packet;
  39 } DVBSubParseContext;
  40
  41 static av_cold int dvbsub_parse_init(AVCodecParserContext *s)
  42 {
  43     DVBSubParseContext *pc = s->priv_data;
  44     pc->packet_buf = av_malloc(PARSE_BUF_SIZE);
  45
  46     return 0;
  47 }
  48
  49 static int dvbsub_parse(AVCodecParserContext *s,
  50                         AVCodecContext *avctx,
  51                         const uint8_t **poutbuf, int *poutbuf_size,
  52                         const uint8_t *buf, int buf_size)
  53 {
  54     DVBSubParseContext *pc = s->priv_data;
  55     uint8_t *p, *p_end;
  56     int len, buf_pos = 0;
  57
  58 #ifdef DEBUG
  59     av_log(avctx, AV_LOG_INFO, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
  60             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
  61 #endif
  62
  63 #ifdef DEBUG_PACKET_CONTENTS
  64     int i;
  65
  66     for (i=0; i < buf_size; i++)
  67     {
  68         av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
  69         if (i % 16 == 15)
  70             av_log(avctx, AV_LOG_INFO, "\n");
  71     }
  72
  73     if (i % 16 != 0)
  74         av_log(avctx, AV_LOG_INFO, "\n");
  75
  76 #endif
  77
  78     *poutbuf = NULL;
  79     *poutbuf_size = 0;
  80
  81     s->fetch_timestamp = 1;
  82
  83     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
  84     {
  85         if (pc->packet_index != pc->packet_start)
  86         {
  87 #ifdef DEBUG
  88             av_log(avctx, AV_LOG_INFO, "Discarding %d bytes\n",
  89                 pc->packet_index - pc->packet_start);
  90 #endif
  91         }
  92
  93         pc->packet_start = 0;
  94         pc->packet_index = 0;
  95
  96         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
  97 #ifdef DEBUG
  98             av_log(avctx, AV_LOG_INFO, "Bad packet header\n");
  99 #endif
 100             return -1;
 101         }
 102
 103         buf_pos = 2;
 104
 105         pc->in_packet = 1;
 106     } else {
 107         if (pc->packet_start != 0)
 108         {
 109             if (pc->packet_index != pc->packet_start)
 110             {
 111                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
 112                             pc->packet_index - pc->packet_start);
 113
 114                 pc->packet_index -= pc->packet_start;
 115                 pc->packet_start = 0;
 116             } else {
 117                 pc->packet_start = 0;
 118                 pc->packet_index = 0;
 119             }
 120         }
 121     }
 122
 123     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
 124         return -1;
 125
 126 /* if not currently in a packet, discard data */
 127     if (pc->in_packet == 0)
 128         return buf_size;
 129
 130     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
 131     pc->packet_index += buf_size - buf_pos;
 132
 133     p = pc->packet_buf;
 134     p_end = pc->packet_buf + pc->packet_index;
 135
 136     while (p < p_end)
 137     {
 138         if (*p == 0x0f)
 139         {
 140             if (p + 6 <= p_end)
 141             {
 142                 len = AV_RB16(p + 4);
 143
 144                 if (p + len + 6 <= p_end)
 145                 {
 146                     *poutbuf_size += len + 6;
 147
 148                     p += len + 6;
 149                 } else
 150                     break;
 151             } else
 152                 break;
 153         } else if (*p == 0xff) {
 154             if (p + 1 < p_end)
 155             {
 156 #ifdef DEBUG
 157                 av_log(avctx, AV_LOG_INFO, "Junk at end of packet\n");
 158 #endif
 159             }
 160             pc->packet_index = p - pc->packet_buf;
 161             pc->in_packet = 0;
 162             break;
 163         } else {
 164             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
 165
 166             pc->packet_index = p - pc->packet_buf;
 167             pc->in_packet = 0;
 168             break;
 169         }
 170     }
 171
 172     if (*poutbuf_size > 0)
 173     {
 174         *poutbuf = pc->packet_buf;
 175         pc->packet_start = *poutbuf_size;
 176     }
 177
 178     if (s->pts == AV_NOPTS_VALUE)
 179         s->pts = s->last_pts;
 180
 181     return buf_size;
 182 }
 183
 184 static av_cold void dvbsub_parse_close(AVCodecParserContext *s)
 185 {
 186     DVBSubParseContext *pc = s->priv_data;
 187     av_freep(&pc->packet_buf);
 188 }
 189
 190 AVCodecParser dvbsub_parser = {
 191     { CODEC_ID_DVB_SUBTITLE },
 192     sizeof(DVBSubParseContext),
 193     dvbsub_parse_init,
 194     dvbsub_parse,
 195     dvbsub_parse_close,
 196 };