libavcodec/dvdsub_parser.c

   1 /*
   2  * DVD subtitle decoding for ffmpeg
   3  * Copyright (c) 2005 Fabrice Bellard
   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 "libavutil/intreadwrite.h"
  23 #include "avcodec.h"
  24
  25 /* parser definition */
  26 typedef struct DVDSubParseContext {
  27     uint8_t *packet;
  28     int packet_len;
  29     int packet_index;
  30 } DVDSubParseContext;
  31
  32 static av_cold int dvdsub_parse_init(AVCodecParserContext *s)
  33 {
  34     return 0;
  35 }
  36
  37 static int dvdsub_parse(AVCodecParserContext *s,
  38                         AVCodecContext *avctx,
  39                         const uint8_t **poutbuf, int *poutbuf_size,
  40                         const uint8_t *buf, int buf_size)
  41 {
  42     DVDSubParseContext *pc = s->priv_data;
  43
  44     if (pc->packet_index == 0) {
  45         if (buf_size < 2)
  46             return 0;
  47         pc->packet_len = AV_RB16(buf);
  48         if (pc->packet_len == 0) /* HD-DVD subpicture packet */
  49             pc->packet_len = AV_RB32(buf+2);
  50         av_freep(&pc->packet);
  51         pc->packet = av_malloc(pc->packet_len);
  52     }
  53     if (pc->packet) {
  54         if (pc->packet_index + buf_size <= pc->packet_len) {
  55             memcpy(pc->packet + pc->packet_index, buf, buf_size);
  56             pc->packet_index += buf_size;
  57             if (pc->packet_index >= pc->packet_len) {
  58                 *poutbuf = pc->packet;
  59                 *poutbuf_size = pc->packet_len;
  60                 pc->packet_index = 0;
  61                 return buf_size;
  62             }
  63         } else {
  64             /* erroneous size */
  65             pc->packet_index = 0;
  66         }
  67     }
  68     *poutbuf = NULL;
  69     *poutbuf_size = 0;
  70     return buf_size;
  71 }
  72
  73 static av_cold void dvdsub_parse_close(AVCodecParserContext *s)
  74 {
  75     DVDSubParseContext *pc = s->priv_data;
  76     av_freep(&pc->packet);
  77 }
  78
  79 AVCodecParser dvdsub_parser = {
  80     { CODEC_ID_DVD_SUBTITLE },
  81     sizeof(DVDSubParseContext),
  82     dvdsub_parse_init,
  83     dvdsub_parse,
  84     dvdsub_parse_close,
  85 };