1/*
2 * MPEG4 Video frame extraction
3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 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#include "parser.h"
24#include "mpegvideo.h"
25#include "mpeg4video_parser.h"
26
27
28int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){
29    int vop_found, i;
30    uint32_t state;
31
32    vop_found= pc->frame_start_found;
33    state= pc->state;
34
35    i=0;
36    if(!vop_found){
37        for(i=0; i<buf_size; i++){
38            state= (state<<8) | buf[i];
39            if(state == 0x1B6){
40                i++;
41                vop_found=1;
42                break;
43            }
44        }
45    }
46
47    if(vop_found){
48        /* EOF considered as end of frame */
49        if (buf_size == 0)
50            return 0;
51        for(; i<buf_size; i++){
52            state= (state<<8) | buf[i];
53            if((state&0xFFFFFF00) == 0x100){
54                pc->frame_start_found=0;
55                pc->state=-1;
56                return i-3;
57            }
58        }
59    }
60    pc->frame_start_found= vop_found;
61    pc->state= state;
62    return END_NOT_FOUND;
63}
64
65/* XXX: make it use less memory */
66static int av_mpeg4_decode_header(AVCodecParserContext *s1,
67                                  AVCodecContext *avctx,
68                                  const uint8_t *buf, int buf_size)
69{
70    ParseContext1 *pc = s1->priv_data;
71    MpegEncContext *s = pc->enc;
72    GetBitContext gb1, *gb = &gb1;
73    int ret;
74
75    s->avctx = avctx;
76    s->current_picture_ptr = &s->current_picture;
77
78    if (avctx->extradata_size && pc->first_picture){
79        init_get_bits(gb, avctx->extradata, avctx->extradata_size*8);
80        ret = ff_mpeg4_decode_picture_header(s, gb);
81    }
82
83    init_get_bits(gb, buf, 8 * buf_size);
84    ret = ff_mpeg4_decode_picture_header(s, gb);
85    if (s->width) {
86        avcodec_set_dimensions(avctx, s->width, s->height);
87    }
88    s1->pict_type= s->pict_type;
89    pc->first_picture = 0;
90    return ret;
91}
92
93static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
94{
95    ParseContext1 *pc = s->priv_data;
96
97    pc->enc = av_mallocz(sizeof(MpegEncContext));
98    if (!pc->enc)
99        return -1;
100    pc->first_picture = 1;
101    return 0;
102}
103
104static int mpeg4video_parse(AVCodecParserContext *s,
105                           AVCodecContext *avctx,
106                           const uint8_t **poutbuf, int *poutbuf_size,
107                           const uint8_t *buf, int buf_size)
108{
109    ParseContext *pc = s->priv_data;
110    int next;
111
112    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
113        next= buf_size;
114    }else{
115        next= ff_mpeg4_find_frame_end(pc, buf, buf_size);
116
117        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
118            *poutbuf = NULL;
119            *poutbuf_size = 0;
120            return buf_size;
121        }
122    }
123    av_mpeg4_decode_header(s, avctx, buf, buf_size);
124
125    *poutbuf = buf;
126    *poutbuf_size = buf_size;
127    return next;
128}
129
130
131AVCodecParser mpeg4video_parser = {
132    { CODEC_ID_MPEG4 },
133    sizeof(ParseContext1),
134    mpeg4video_parse_init,
135    mpeg4video_parse,
136    ff_parse1_close,
137    ff_mpeg4video_split,
138};
139