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2ba45a60 DM |
1 | /* |
2 | * H261 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 | * h261codec. | |
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 | }; |