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.h"
26#include "mpeg4video_parser.h"
27
28
29int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){
30    int vop_found, i;
31    uint32_t state;
32
33    vop_found= pc->frame_start_found;
34    state= pc->state;
35
36    i=0;
37    if(!vop_found){
38        for(i=0; i<buf_size; i++){
39            state= (state<<8) | buf[i];
40            if(state == 0x1B6){
41                i++;
42                vop_found=1;
43                break;
44            }
45        }
46    }
47
48    if(vop_found){
49        /* EOF considered as end of frame */
50        if (buf_size == 0)
51            return 0;
52        for(; i<buf_size; i++){
53            state= (state<<8) | buf[i];
54            if((state&0xFFFFFF00) == 0x100){
55                pc->frame_start_found=0;
56                pc->state=-1;
57                return i-3;
58            }
59        }
60    }
61    pc->frame_start_found= vop_found;
62    pc->state= state;
63    return END_NOT_FOUND;
64}
65
66/* XXX: make it use less memory */
67static int av_mpeg4_decode_header(AVCodecParserContext *s1,
68                                  AVCodecContext *avctx,
69                                  const uint8_t *buf, int buf_size)
70{
71    ParseContext1 *pc = s1->priv_data;
72    MpegEncContext *s = pc->enc;
73    GetBitContext gb1, *gb = &gb1;
74    int ret;
75
76    s->avctx = avctx;
77    s->current_picture_ptr = &s->current_picture;
78
79    if (avctx->extradata_size && pc->first_picture){
80        init_get_bits(gb, avctx->extradata, avctx->extradata_size*8);
81        ret = ff_mpeg4_decode_picture_header(s, gb);
82    }
83
84    init_get_bits(gb, buf, 8 * buf_size);
85    ret = ff_mpeg4_decode_picture_header(s, gb);
86    if (s->width && (!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height)) {
87        avcodec_set_dimensions(avctx, s->width, s->height);
88    }
89    s1->pict_type= s->pict_type;
90    pc->first_picture = 0;
91    return ret;
92}
93
94static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
95{
96    ParseContext1 *pc = s->priv_data;
97
98    pc->enc = av_mallocz(sizeof(MpegEncContext));
99    if (!pc->enc)
100        return -1;
101    pc->first_picture = 1;
102    return 0;
103}
104
105static int mpeg4video_parse(AVCodecParserContext *s,
106                           AVCodecContext *avctx,
107                           const uint8_t **poutbuf, int *poutbuf_size,
108                           const uint8_t *buf, int buf_size)
109{
110    ParseContext *pc = s->priv_data;
111    int next;
112
113    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
114        next= buf_size;
115    }else{
116        next= ff_mpeg4_find_frame_end(pc, buf, buf_size);
117
118        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
119            *poutbuf = NULL;
120            *poutbuf_size = 0;
121            return buf_size;
122        }
123    }
124    av_mpeg4_decode_header(s, avctx, buf, buf_size);
125
126    *poutbuf = buf;
127    *poutbuf_size = buf_size;
128    return next;
129}
130
131
132AVCodecParser mpeg4video_parser = {
133    { CODEC_ID_MPEG4 },
134    sizeof(ParseContext1),
135    mpeg4video_parse_init,
136    mpeg4video_parse,
137    ff_parse1_close,
138    ff_mpeg4video_split,
139};
140