blob: 2299c1cfc5978a4a84b58ee8a7e6acfe04067a46
1 | /* |
2 | * H.261 parser |
3 | * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
4 | * Copyright (c) 2004 Maarten Daniels |
5 | * |
6 | * This file is part of FFmpeg. |
7 | * |
8 | * FFmpeg is free software; you can redistribute it and/or |
9 | * modify it under the terms of the GNU Lesser General Public |
10 | * License as published by the Free Software Foundation; either |
11 | * version 2.1 of the License, or (at your option) any later version. |
12 | * |
13 | * FFmpeg is distributed in the hope that it will be useful, |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
16 | * Lesser General Public License for more details. |
17 | * |
18 | * You should have received a copy of the GNU Lesser General Public |
19 | * License along with FFmpeg; if not, write to the Free Software |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
21 | */ |
22 | |
23 | /** |
24 | * @file |
25 | * H.261 parser |
26 | */ |
27 | |
28 | #include "parser.h" |
29 | |
30 | static int h261_find_frame_end(ParseContext *pc, AVCodecContext *avctx, |
31 | const uint8_t *buf, int buf_size) |
32 | { |
33 | int vop_found, i, j; |
34 | uint32_t state; |
35 | |
36 | vop_found = pc->frame_start_found; |
37 | state = pc->state; |
38 | |
39 | for (i = 0; i < buf_size && !vop_found; i++) { |
40 | state = (state << 8) | buf[i]; |
41 | for (j = 0; j < 8; j++) { |
42 | if (((state >> j) & 0xFFFFF0) == 0x000100) { |
43 | vop_found = 1; |
44 | break; |
45 | } |
46 | } |
47 | } |
48 | if (vop_found) { |
49 | for (; i < buf_size; i++) { |
50 | state = (state << 8) | buf[i]; |
51 | for (j = 0; j < 8; j++) { |
52 | if (((state >> j) & 0xFFFFF0) == 0x000100) { |
53 | pc->frame_start_found = 0; |
54 | pc->state = (state >> (3 * 8)) + 0xFF00; |
55 | return i - 2; |
56 | } |
57 | } |
58 | } |
59 | } |
60 | |
61 | pc->frame_start_found = vop_found; |
62 | pc->state = state; |
63 | return END_NOT_FOUND; |
64 | } |
65 | |
66 | static int h261_parse(AVCodecParserContext *s, |
67 | AVCodecContext *avctx, |
68 | const uint8_t **poutbuf, int *poutbuf_size, |
69 | const uint8_t *buf, int buf_size) |
70 | { |
71 | ParseContext *pc = s->priv_data; |
72 | int next; |
73 | |
74 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { |
75 | next = buf_size; |
76 | } else { |
77 | next = h261_find_frame_end(pc, avctx, buf, buf_size); |
78 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
79 | *poutbuf = NULL; |
80 | *poutbuf_size = 0; |
81 | return buf_size; |
82 | } |
83 | } |
84 | *poutbuf = buf; |
85 | *poutbuf_size = buf_size; |
86 | return next; |
87 | } |
88 | |
89 | AVCodecParser ff_h261_parser = { |
90 | .codec_ids = { AV_CODEC_ID_H261 }, |
91 | .priv_data_size = sizeof(ParseContext), |
92 | .parser_parse = h261_parse, |
93 | .parser_close = ff_parse_close, |
94 | }; |
95 |