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
32typedef 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
45static 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
100const 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