FFmpeg
cri_parser.c
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1 /*
2  * CRI 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  * CRI parser
25  */
26 
27 #include "libavutil/bswap.h"
28 #include "libavutil/common.h"
29 
30 #include "parser.h"
31 
32 typedef struct CRIParser {
34  int count;
35  int chunk;
38 } CRIParser;
39 
40 #define KEY (((uint64_t)'\1' << 56) | ((uint64_t)'\0' << 48) | \
41  ((uint64_t)'\0' << 40) | ((uint64_t)'\0' << 32) | \
42  ((uint64_t)'\4' << 24) | ((uint64_t)'\0' << 16) | \
43  ((uint64_t)'\0' << 8) | ((uint64_t)'\0' << 0))
44 
46  const uint8_t **poutbuf, int *poutbuf_size,
47  const uint8_t *buf, int buf_size)
48 {
49  CRIParser *bpc = s->priv_data;
50  uint64_t state = bpc->pc.state64;
51  int next = END_NOT_FOUND, i = 0;
52 
53  s->pict_type = AV_PICTURE_TYPE_I;
54  s->key_frame = 1;
55  s->duration = 1;
56 
57  *poutbuf_size = 0;
58  *poutbuf = NULL;
59 
60  for (; i < buf_size; i++) {
61  state = (state << 8) | buf[i];
62  bpc->read_bytes++;
63 
64  if (bpc->skip_bytes > 0) {
65  bpc->skip_bytes--;
66  if (bpc->skip_bytes == 0)
67  bpc->read_bytes = 0;
68  } else {
69  if (state != KEY)
70  continue;
71  }
72 
73  if (bpc->skip_bytes == 0 && bpc->read_bytes >= 8) {
74  bpc->skip_bytes = av_bswap32(state & 0xFFFFFFFF);
75  bpc->chunk = state >> 32;
76  bpc->read_bytes = 0;
77  bpc->count++;
78  }
79 
80  if (bpc->chunk == 0x01000000 && bpc->skip_bytes == 4 &&
81  bpc->read_bytes == 0 && bpc->count > 1) {
82  next = i - 7;
83  break;
84  }
85  }
86 
87  bpc->pc.state64 = state;
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_CRI },
102  .priv_data_size = sizeof(CRIParser),
103  .parser_parse = cri_parse,
104  .parser_close = ff_parse_close,
105 };
cri_parse
static int cri_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: cri_parser.c:45
state
static struct @321 state
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:282
ParseContext
Definition: parser.h:28
av_bswap32
#define av_bswap32
Definition: bswap.h:33
CRIParser
Definition: cri_parser.c:32
s
#define s(width, name)
Definition: cbs_vp9.c:257
CRIParser::chunk
int chunk
Definition: cri_parser.c:35
CRIParser::pc
ParseContext pc
Definition: cri_parser.c:33
CRIParser::read_bytes
int read_bytes
Definition: cri_parser.c:36
NULL
#define NULL
Definition: coverity.c:32
AVCodecParser::codec_ids
int codec_ids[5]
Definition: avcodec.h:3040
AV_PICTURE_TYPE_I
@ AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:274
KEY
#define KEY
Definition: cri_parser.c:40
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:197
i
int i
Definition: input.c:407
AV_CODEC_ID_CRI
@ AV_CODEC_ID_CRI
Definition: codec_id.h:306
CRIParser::skip_bytes
int skip_bytes
Definition: cri_parser.c:37
common.h
parser.h
AVCodecParserContext
Definition: avcodec.h:2880
bswap.h
AVCodecContext
main external API structure.
Definition: avcodec.h:501
CRIParser::count
int count
Definition: cri_parser.c:34
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:3039
ff_cri_parser
const AVCodecParser ff_cri_parser
Definition: cri_parser.c:100