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 {
33 ParseContext pc;
34 int count;
35 int chunk;
36 int read_bytes;
37 int skip_bytes;
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
cri_parse(AVCodecParserContext * s,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)45 static int cri_parse(AVCodecParserContext *s, AVCodecContext *avctx,
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
100 AVCodecParser ff_cri_parser = {
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 };
106