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2ba45a60 DM |
1 | /* |
2 | * PNG parser | |
3 | * Copyright (c) 2009 Peter Holik | |
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 | /** | |
23 | * @file | |
24 | * PNG parser | |
25 | */ | |
26 | ||
27 | #include "parser.h" | |
28 | #include "png.h" | |
29 | ||
30 | typedef struct PNGParseContext { | |
31 | ParseContext pc; | |
32 | uint32_t chunk_pos; ///< position inside current chunk | |
33 | uint32_t chunk_length; ///< length of the current chunk | |
34 | uint32_t remaining_size; ///< remaining size of the current chunk | |
35 | } PNGParseContext; | |
36 | ||
37 | static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx, | |
38 | const uint8_t **poutbuf, int *poutbuf_size, | |
39 | const uint8_t *buf, int buf_size) | |
40 | { | |
41 | PNGParseContext *ppc = s->priv_data; | |
42 | int next = END_NOT_FOUND; | |
43 | int i = 0; | |
44 | ||
45 | s->pict_type = AV_PICTURE_TYPE_NONE; | |
46 | ||
47 | *poutbuf_size = 0; | |
48 | ||
49 | if (!ppc->pc.frame_start_found) { | |
50 | uint64_t state64 = ppc->pc.state64; | |
51 | for (; i < buf_size; i++) { | |
52 | state64 = (state64 << 8) | buf[i]; | |
53 | if (state64 == PNGSIG || state64 == MNGSIG) { | |
54 | i++; | |
55 | ppc->pc.frame_start_found = 1; | |
56 | break; | |
57 | } | |
58 | } | |
59 | ppc->pc.state64 = state64; | |
60 | } else if (ppc->remaining_size) { | |
61 | i = FFMIN(ppc->remaining_size, buf_size); | |
62 | ppc->remaining_size -= i; | |
63 | if (ppc->remaining_size) | |
64 | goto flush; | |
65 | if (ppc->chunk_pos == -1) { | |
66 | next = i; | |
67 | goto flush; | |
68 | } | |
69 | } | |
70 | ||
71 | for (; ppc->pc.frame_start_found && i < buf_size; i++) { | |
72 | ppc->pc.state = (ppc->pc.state << 8) | buf[i]; | |
73 | if (ppc->chunk_pos == 3) { | |
74 | ppc->chunk_length = ppc->pc.state; | |
75 | if (ppc->chunk_length > 0x7fffffff) { | |
76 | ppc->chunk_pos = ppc->pc.frame_start_found = 0; | |
77 | goto flush; | |
78 | } | |
79 | ppc->chunk_length += 4; | |
80 | } else if (ppc->chunk_pos == 7) { | |
81 | if (ppc->chunk_length >= buf_size - i) | |
82 | ppc->remaining_size = ppc->chunk_length - buf_size + i + 1; | |
83 | if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) { | |
84 | if (ppc->remaining_size) | |
85 | ppc->chunk_pos = -1; | |
86 | else | |
87 | next = ppc->chunk_length + i + 1; | |
88 | break; | |
89 | } else { | |
90 | ppc->chunk_pos = 0; | |
91 | if (ppc->remaining_size) | |
92 | break; | |
93 | else | |
94 | i += ppc->chunk_length; | |
95 | continue; | |
96 | } | |
97 | } | |
98 | ppc->chunk_pos++; | |
99 | } | |
100 | ||
101 | flush: | |
102 | if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0) | |
103 | return buf_size; | |
104 | ||
105 | ppc->chunk_pos = ppc->pc.frame_start_found = 0; | |
106 | ||
107 | *poutbuf = buf; | |
108 | *poutbuf_size = buf_size; | |
109 | return next; | |
110 | } | |
111 | ||
112 | AVCodecParser ff_png_parser = { | |
113 | .codec_ids = { AV_CODEC_ID_PNG }, | |
114 | .priv_data_size = sizeof(PNGParseContext), | |
115 | .parser_parse = png_parse, | |
116 | .parser_close = ff_parse_close, | |
117 | }; |