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     dprintf(avctx, "DVB parse packet pts=%"PRIx64", lpts=%"PRIx64", cpts=%"PRIx64":\n",
  59             s->pts, s->last_pts, s->cur_frame_pts[s->cur_frame_start_index]);
  60
  61 #ifdef DEBUG_PACKET_CONTENTS
  62     int i;
  63
  64     for (i=0; i < buf_size; i++)
  65     {
  66         av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
  67         if (i % 16 == 15)
  68             av_log(avctx, AV_LOG_INFO, "\n");
  69     }
  70
  71     if (i % 16 != 0)
  72         av_log(avctx, AV_LOG_INFO, "\n");
  73
  74 #endif
  75
  76     *poutbuf = NULL;
  77     *poutbuf_size = 0;
  78
  79     s->fetch_timestamp = 1;
  80
  81     if (s->last_pts != s->pts && s->pts != AV_NOPTS_VALUE) /* Start of a new packet */
  82     {
  83         if (pc->packet_index != pc->packet_start)
  84         {
  85             dprintf(avctx, "Discarding %d bytes\n",
  86                     pc->packet_index - pc->packet_start);
  87         }
  88
  89         pc->packet_start = 0;
  90         pc->packet_index = 0;
  91
  92         if (buf_size < 2 || buf[0] != 0x20 || buf[1] != 0x00) {
  93             dprintf(avctx, "Bad packet header\n");
  94             return -1;
  95         }
  96
  97         buf_pos = 2;
  98
  99         pc->in_packet = 1;
 100     } else {
 101         if (pc->packet_start != 0)
 102         {
 103             if (pc->packet_index != pc->packet_start)
 104             {
 105                 memmove(pc->packet_buf, pc->packet_buf + pc->packet_start,
 106                             pc->packet_index - pc->packet_start);
 107
 108                 pc->packet_index -= pc->packet_start;
 109                 pc->packet_start = 0;
 110             } else {
 111                 pc->packet_start = 0;
 112                 pc->packet_index = 0;
 113             }
 114         }
 115     }
 116
 117     if (buf_size - buf_pos + pc->packet_index > PARSE_BUF_SIZE)
 118         return -1;
 119
 120 /* if not currently in a packet, discard data */
 121     if (pc->in_packet == 0)
 122         return buf_size;
 123
 124     memcpy(pc->packet_buf + pc->packet_index, buf + buf_pos, buf_size - buf_pos);
 125     pc->packet_index += buf_size - buf_pos;
 126
 127     p = pc->packet_buf;
 128     p_end = pc->packet_buf + pc->packet_index;
 129
 130     while (p < p_end)
 131     {
 132         if (*p == 0x0f)
 133         {
 134             if (p + 6 <= p_end)
 135             {
 136                 len = AV_RB16(p + 4);
 137
 138                 if (p + len + 6 <= p_end)
 139                 {
 140                     *poutbuf_size += len + 6;
 141
 142                     p += len + 6;
 143                 } else
 144                     break;
 145             } else
 146                 break;
 147         } else if (*p == 0xff) {
 148             if (p + 1 < p_end)
 149             {
 150                 dprintf(avctx, "Junk at end of packet\n");
 151             }
 152             pc->packet_index = p - pc->packet_buf;
 153             pc->in_packet = 0;
 154             break;
 155         } else {
 156             av_log(avctx, AV_LOG_ERROR, "Junk in packet\n");
 157
 158             pc->packet_index = p - pc->packet_buf;
 159             pc->in_packet = 0;
 160             break;
 161         }
 162     }
 163
 164     if (*poutbuf_size > 0)
 165     {
 166         *poutbuf = pc->packet_buf;
 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 dvbsub_parser = {
 183     { CODEC_ID_DVB_SUBTITLE },
 184     sizeof(DVBSubParseContext),
 185     dvbsub_parse_init,
 186     dvbsub_parse,
 187     dvbsub_parse_close,
 188 };