1/*
2 * VC-1 and WMV3 parser
3 * Copyright (c) 2006-2007 Konstantin Shishkov
4 * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23/**
24 * @file libavcodec/vc1_parser.c
25 * VC-1 and WMV3 parser
26 */
27
28#include "parser.h"
29#include "vc1.h"
30
31/**
32 * finds the end of the current frame in the bitstream.
33 * @return the position of the first byte of the next frame, or -1
34 */
35static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,
36                               int buf_size) {
37    int pic_found, i;
38    uint32_t state;
39
40    pic_found= pc->frame_start_found;
41    state= pc->state;
42
43    i=0;
44    if(!pic_found){
45        for(i=0; i<buf_size; i++){
46            state= (state<<8) | buf[i];
47            if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){
48                i++;
49                pic_found=1;
50                break;
51            }
52        }
53    }
54
55    if(pic_found){
56        /* EOF considered as end of frame */
57        if (buf_size == 0)
58            return 0;
59        for(; i<buf_size; i++){
60            state= (state<<8) | buf[i];
61            if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){
62                pc->frame_start_found=0;
63                pc->state=-1;
64                return i-3;
65            }
66        }
67    }
68    pc->frame_start_found= pic_found;
69    pc->state= state;
70    return END_NOT_FOUND;
71}
72
73static int vc1_parse(AVCodecParserContext *s,
74                           AVCodecContext *avctx,
75                           const uint8_t **poutbuf, int *poutbuf_size,
76                           const uint8_t *buf, int buf_size)
77{
78    ParseContext *pc = s->priv_data;
79    int next;
80
81    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
82        next= buf_size;
83    }else{
84        next= vc1_find_frame_end(pc, buf, buf_size);
85
86        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
87            *poutbuf = NULL;
88            *poutbuf_size = 0;
89            return buf_size;
90        }
91    }
92    *poutbuf = buf;
93    *poutbuf_size = buf_size;
94    return next;
95}
96
97static int vc1_split(AVCodecContext *avctx,
98                           const uint8_t *buf, int buf_size)
99{
100    int i;
101    uint32_t state= -1;
102    int charged=0;
103
104    for(i=0; i<buf_size; i++){
105        state= (state<<8) | buf[i];
106        if(IS_MARKER(state)){
107            if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){
108                charged=1;
109            }else if(charged){
110                return i-3;
111            }
112        }
113    }
114    return 0;
115}
116
117AVCodecParser vc1_parser = {
118    { CODEC_ID_VC1 },
119    sizeof(ParseContext1),
120    NULL,
121    vc1_parse,
122    ff_parse1_close,
123    vc1_split,
124};
125