libavcodec/dvdsub_parser.c

   1 /*
   2  * DVD subtitle decoding
   3  * Copyright (c) 2005 Fabrice Bellard
   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 <string.h>
  23
  24 #include "libavutil/intreadwrite.h"
  25 #include "libavutil/mem.h"
  26 #include "avcodec.h"
  27
  28 /* parser definition */
  29 typedef struct DVDSubParseContext {
  30     uint8_t *packet;
  31     int packet_len;
  32     int packet_index;
  33 } DVDSubParseContext;
  34
  35 static av_cold int dvdsub_parse_init(AVCodecParserContext *s)
  36 {
  37     return 0;
  38 }
  39
  40 static int dvdsub_parse(AVCodecParserContext *s,
  41                         AVCodecContext *avctx,
  42                         const uint8_t **poutbuf, int *poutbuf_size,
  43                         const uint8_t *buf, int buf_size)
  44 {
  45     DVDSubParseContext *pc = s->priv_data;
  46
  47     if (pc->packet_index == 0) {
  48         if (buf_size < 2)
  49             return 0;
  50         pc->packet_len = AV_RB16(buf);
  51         if (pc->packet_len == 0) /* HD-DVD subpicture packet */
  52             pc->packet_len = AV_RB32(buf+2);
  53         av_freep(&pc->packet);
  54         pc->packet = av_malloc(pc->packet_len);
  55     }
  56     if (pc->packet) {
  57         if (pc->packet_index + buf_size <= pc->packet_len) {
  58             memcpy(pc->packet + pc->packet_index, buf, buf_size);
  59             pc->packet_index += buf_size;
  60             if (pc->packet_index >= pc->packet_len) {
  61                 *poutbuf = pc->packet;
  62                 *poutbuf_size = pc->packet_len;
  63                 pc->packet_index = 0;
  64                 return buf_size;
  65             }
  66         } else {
  67             /* erroneous size */
  68             pc->packet_index = 0;
  69         }
  70     }
  71     *poutbuf = NULL;
  72     *poutbuf_size = 0;
  73     return buf_size;
  74 }
  75
  76 static av_cold void dvdsub_parse_close(AVCodecParserContext *s)
  77 {
  78     DVDSubParseContext *pc = s->priv_data;
  79     av_freep(&pc->packet);
  80 }
  81
  82 AVCodecParser ff_dvdsub_parser = {
  83     .codec_ids      = { AV_CODEC_ID_DVD_SUBTITLE },
  84     .priv_data_size = sizeof(DVDSubParseContext),
  85     .parser_init    = dvdsub_parse_init,
  86     .parser_parse   = dvdsub_parse,
  87     .parser_close   = dvdsub_parse_close,
  88 };