h261: Signal freeze picture release for intra frames
[ffmpeg.git] / libavcodec / xiph.c
1 /*
2  * Copyright (C) 2007  Libav Project
3  *
4  * This file is part of Libav.
5  *
6  * Libav is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * Libav is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20
21 #include "libavutil/intreadwrite.h"
22 #include "xiph.h"
23
24 int avpriv_split_xiph_headers(uint8_t *extradata, int extradata_size,
25                           int first_header_size, uint8_t *header_start[3],
26                           int header_len[3])
27 {
28     int i;
29
30     if (extradata_size >= 6 && AV_RB16(extradata) == first_header_size) {
31         int overall_len = 6;
32         for (i=0; i<3; i++) {
33             header_len[i] = AV_RB16(extradata);
34             extradata += 2;
35             header_start[i] = extradata;
36             extradata += header_len[i];
37             if (overall_len > extradata_size - header_len[i])
38                 return -1;
39             overall_len += header_len[i];
40         }
41     } else if (extradata_size >= 3 && extradata_size < INT_MAX - 0x1ff && extradata[0] == 2) {
42         int overall_len = 3;
43         extradata++;
44         for (i=0; i<2; i++, extradata++) {
45             header_len[i] = 0;
46             for (; overall_len < extradata_size && *extradata==0xff; extradata++) {
47                 header_len[i] += 0xff;
48                 overall_len   += 0xff + 1;
49             }
50             header_len[i] += *extradata;
51             overall_len   += *extradata;
52             if (overall_len > extradata_size)
53                 return -1;
54         }
55         header_len[2] = extradata_size - overall_len;
56         header_start[0] = extradata;
57         header_start[1] = header_start[0] + header_len[0];
58         header_start[2] = header_start[1] + header_len[1];
59     } else {
60         return -1;
61     }
62     return 0;
63 }