blob: 74f296411810f9624fe5573ec211c8ff8c02bf47
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 | }; |
118 |