1 /*
2 * WebP parser
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * WebP parser
24 */
25
26 #include "libavutil/bswap.h"
27 #include "libavutil/common.h"
28
29 #include "parser.h"
30
31 typedef struct WebPParseContext {
32 ParseContext pc;
33 uint32_t fsize;
34 uint32_t remaining_size;
35 } WebPParseContext;
36
webp_parse(AVCodecParserContext * s,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)37 static int webp_parse(AVCodecParserContext *s, AVCodecContext *avctx,
38 const uint8_t **poutbuf, int *poutbuf_size,
39 const uint8_t *buf, int buf_size)
40 {
41 WebPParseContext *ctx = s->priv_data;
42 uint64_t state = ctx->pc.state64;
43 int next = END_NOT_FOUND;
44 int i = 0;
45
46 *poutbuf = NULL;
47 *poutbuf_size = 0;
48
49 restart:
50 if (ctx->pc.frame_start_found <= 8) {
51 for (; i < buf_size; i++) {
52 state = (state << 8) | buf[i];
53 if (ctx->pc.frame_start_found == 0) {
54 if ((state >> 32) == MKBETAG('R', 'I', 'F', 'F')) {
55 ctx->fsize = av_bswap32(state);
56 if (ctx->fsize > 15 && ctx->fsize <= UINT32_MAX - 10) {
57 ctx->pc.frame_start_found = 1;
58 ctx->fsize += 8;
59 }
60 }
61 } else if (ctx->pc.frame_start_found == 8) {
62 if ((state >> 32) != MKBETAG('W', 'E', 'B', 'P')) {
63 ctx->pc.frame_start_found = 0;
64 continue;
65 }
66 ctx->pc.frame_start_found++;
67 ctx->remaining_size = ctx->fsize + i - 15;
68 if (ctx->pc.index + i > 15) {
69 next = i - 15;
70 state = 0;
71 break;
72 } else {
73 ctx->pc.state64 = 0;
74 goto restart;
75 }
76 } else if (ctx->pc.frame_start_found)
77 ctx->pc.frame_start_found++;
78 }
79 ctx->pc.state64 = state;
80 } else {
81 if (ctx->remaining_size) {
82 i = FFMIN(ctx->remaining_size, buf_size);
83 ctx->remaining_size -= i;
84 if (ctx->remaining_size)
85 goto flush;
86
87 ctx->pc.frame_start_found = 0;
88 goto restart;
89 }
90 }
91
92 flush:
93 if (ff_combine_frame(&ctx->pc, next, &buf, &buf_size) < 0)
94 return buf_size;
95
96 if (next != END_NOT_FOUND && next < 0)
97 ctx->pc.frame_start_found = FFMAX(ctx->pc.frame_start_found - i - 1, 0);
98 else
99 ctx->pc.frame_start_found = 0;
100
101 *poutbuf = buf;
102 *poutbuf_size = buf_size;
103
104 return next;
105 }
106
107 const AVCodecParser ff_webp_parser = {
108 .codec_ids = { AV_CODEC_ID_WEBP },
109 .priv_data_size = sizeof(WebPParseContext),
110 .parser_parse = webp_parse,
111 .parser_close = ff_parse_close,
112 };
113