FFmpeg
xbm_parser.c
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1 /*
2  * XBM parser
3  * Copyright (c) 2021 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  * XBM parser
25  */
26 
27 #include "libavutil/common.h"
28 
29 #include "parser.h"
30 
31 typedef struct XBMParseContext {
33  uint16_t state16;
34  int count;
36 
37 #define KEY (((uint64_t)'\n' << 56) | ((uint64_t)'#' << 48) | \
38  ((uint64_t)'d' << 40) | ((uint64_t)'e' << 32) | \
39  ((uint64_t)'f' << 24) | ('i' << 16) | ('n' << 8) | \
40  ('e' << 0))
41 
42 #define END ((';' << 8) | ('\n' << 0))
43 
45 {
46  XBMParseContext *bpc = s->priv_data;
47 
48  bpc->count = 1;
49 
50  return 0;
51 }
52 
54  const uint8_t **poutbuf, int *poutbuf_size,
55  const uint8_t *buf, int buf_size)
56 {
57  XBMParseContext *bpc = s->priv_data;
58  uint64_t state = bpc->pc.state64;
59  uint16_t state16 = bpc->state16;
60  int next = END_NOT_FOUND, i = 0;
61 
63  s->key_frame = 1;
64  s->duration = 1;
65 
66  *poutbuf_size = 0;
67  *poutbuf = NULL;
68 
69  for (; i < buf_size; i++) {
70  state = (state << 8) | buf[i];
71  state16 = (state16 << 8) | buf[i];
72 
73  if (state == KEY)
74  bpc->count++;
75 
76  if ((state == KEY && bpc->count == 1)) {
77  next = i - 6;
78  break;
79  } else if (state16 == END) {
80  next = i + 1;
81  bpc->count = 0;
82  break;
83  }
84  }
85 
86  bpc->pc.state64 = state;
87  bpc->state16 = state16;
88  if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0) {
89  *poutbuf = NULL;
90  *poutbuf_size = 0;
91  return buf_size;
92  }
93 
94  *poutbuf = buf;
95  *poutbuf_size = buf_size;
96 
97  return next;
98 }
99 
101  .codec_ids = { AV_CODEC_ID_XBM },
102  .priv_data_size = sizeof(XBMParseContext),
103  .parser_init = xbm_init,
104  .parser_parse = xbm_parse,
105  .parser_close = ff_parse_close,
106 };
#define NULL
Definition: coverity.c:32
static int xbm_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: xbm_parser.c:53
AVCodecParser ff_xbm_parser
Definition: xbm_parser.c:100
int codec_ids[5]
Definition: avcodec.h:3545
int duration
Duration of the current frame.
Definition: avcodec.h:3499
#define KEY
Definition: xbm_parser.c:37
uint8_t
static struct @321 state
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:238
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:323
static int xbm_init(AVCodecParserContext *s)
Definition: xbm_parser.c:44
#define s(width, name)
Definition: cbs_vp9.c:257
ParseContext pc
Definition: xbm_parser.c:32
uint16_t state16
Definition: xbm_parser.c:33
main external API structure.
Definition: avcodec.h:536
uint64_t state64
contains the last 8 bytes in MSB order
Definition: parser.h:37
#define END
Definition: xbm_parser.c:42
#define END_NOT_FOUND
Definition: parser.h:40
common internal and external API header
int key_frame
Set by parser to 1 for key frames and 0 for non-key frames.
Definition: avcodec.h:3426
int i
Definition: input.c:407