FFmpeg
bmp_parser.c
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1 /*
2  * BMP parser
3  * Copyright (c) 2012 Paul B Mahol
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  * BMP parser
25  */
26 
27 #include "libavutil/bswap.h"
28 #include "libavutil/common.h"
29 
30 #include "parser.h"
31 
32 typedef struct BMPParseContext {
34  uint32_t fsize;
35  uint32_t remaining_size;
37 
39  const uint8_t **poutbuf, int *poutbuf_size,
40  const uint8_t *buf, int buf_size)
41 {
42  BMPParseContext *bpc = s->priv_data;
43  uint64_t state = bpc->pc.state64;
44  int next = END_NOT_FOUND;
45  int i = 0;
46 
47  *poutbuf_size = 0;
48  *poutbuf = NULL;
49 
50 restart:
51  if (bpc->pc.frame_start_found <= 2+4+4) {
52  for (; i < buf_size; i++) {
53  state = (state << 8) | buf[i];
54  if (bpc->pc.frame_start_found == 0) {
55  if ((state >> 48) == (('B' << 8) | 'M')) {
56  bpc->fsize = av_bswap32(state >> 16);
57  if (bpc->fsize > 17)
58  bpc->pc.frame_start_found = 1;
59  }
60  } else if (bpc->pc.frame_start_found == 2+4+4) {
61 // unsigned hsize = av_bswap32(state>>32);
62  unsigned ihsize = av_bswap32(state);
63  if (ihsize < 12 || ihsize > 200) {
64  bpc->pc.frame_start_found = 0;
65  continue;
66  }
67  bpc->pc.frame_start_found++;
68  bpc->remaining_size = bpc->fsize + i - 17;
69 
70  if (bpc->pc.index + i > 17) {
71  next = i - 17;
72  state = 0;
73  break;
74  } else {
75  bpc->pc.state64 = 0;
76  goto restart;
77  }
78  } else if (bpc->pc.frame_start_found)
79  bpc->pc.frame_start_found++;
80  }
81  bpc->pc.state64 = state;
82  } else {
83  if (bpc->remaining_size) {
84  i = FFMIN(bpc->remaining_size, buf_size);
85  bpc->remaining_size -= i;
86  if (bpc->remaining_size)
87  goto flush;
88 
89  bpc->pc.frame_start_found = 0;
90  goto restart;
91  }
92  }
93 
94 flush:
95  if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0)
96  return buf_size;
97 
98  if (next != END_NOT_FOUND && next < 0)
99  bpc->pc.frame_start_found = FFMAX(bpc->pc.frame_start_found - i - 1, 0);
100  else
101  bpc->pc.frame_start_found = 0;
102 
103  *poutbuf = buf;
104  *poutbuf_size = buf_size;
105  return next;
106 }
107 
109  .codec_ids = { AV_CODEC_ID_BMP },
110  .priv_data_size = sizeof(BMPParseContext),
111  .parser_parse = bmp_parse,
112  .parser_close = ff_parse_close,
113 };
BMPParseContext::fsize
uint32_t fsize
Definition: bmp_parser.c:34
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:290
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
BMPParseContext::pc
ParseContext pc
Definition: bmp_parser.c:33
ParseContext
Definition: parser.h:28
bmp_parse
static int bmp_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: bmp_parser.c:38
ParseContext::index
int index
Definition: parser.h:30
s
#define s(width, name)
Definition: cbs_vp9.c:198
AV_CODEC_ID_BMP
@ AV_CODEC_ID_BMP
Definition: codec_id.h:130
NULL
#define NULL
Definition: coverity.c:32
ParseContext::frame_start_found
int frame_start_found
Definition: parser.h:34
flush
void(* flush)(AVBSFContext *ctx)
Definition: dts2pts.c:370
AVCodecParser::codec_ids
int codec_ids[7]
Definition: avcodec.h:2908
av_bswap32
#define av_bswap32
Definition: bswap.h:47
BMPParseContext
Definition: bmp_parser.c:32
ff_combine_frame
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:203
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
state
static struct @457 state
common.h
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
parser.h
BMPParseContext::remaining_size
uint32_t remaining_size
Definition: bmp_parser.c:35
AVCodecParserContext
Definition: avcodec.h:2748
bswap.h
AVCodecContext
main external API structure.
Definition: avcodec.h:451
ParseContext::state64
uint64_t state64
contains the last 8 bytes in MSB order
Definition: parser.h:37
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
AVCodecParser
Definition: avcodec.h:2907
ff_bmp_parser
const AVCodecParser ff_bmp_parser
Definition: bmp_parser.c:108