1/*
2 * MPEG1 / MPEG2 video parser
3 * Copyright (c) 2000,2001 Fabrice Bellard
4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
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 "mpeg12.h"
25#include "internal.h"
26
27struct MpvParseContext {
28    ParseContext pc;
29    AVRational frame_rate;
30    int progressive_sequence;
31    int width, height;
32};
33
34
35static void mpegvideo_extract_headers(AVCodecParserContext *s,
36                                      AVCodecContext *avctx,
37                                      const uint8_t *buf, int buf_size)
38{
39    struct MpvParseContext *pc = s->priv_data;
40    const uint8_t *buf_end = buf + buf_size;
41    uint32_t start_code;
42    int frame_rate_index, ext_type, bytes_left;
43    int frame_rate_ext_n, frame_rate_ext_d;
44    int top_field_first, repeat_first_field, progressive_frame;
45    int horiz_size_ext, vert_size_ext, bit_rate_ext;
46    int did_set_size=0;
47    int bit_rate = 0;
48    int vbv_delay = 0;
49//FIXME replace the crap with get_bits()
50    s->repeat_pict = 0;
51
52    while (buf < buf_end) {
53        start_code= -1;
54        buf= avpriv_find_start_code(buf, buf_end, &start_code);
55        bytes_left = buf_end - buf;
56        switch(start_code) {
57        case PICTURE_START_CODE:
58            if (bytes_left >= 2) {
59                s->pict_type = (buf[1] >> 3) & 7;
60                if (bytes_left >= 4)
61                vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3]  >> 3);
62            }
63            break;
64        case SEQ_START_CODE:
65            if (bytes_left >= 7) {
66                pc->width  = (buf[0] << 4) | (buf[1] >> 4);
67                pc->height = ((buf[1] & 0x0f) << 8) | buf[2];
68                if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){
69                    ff_set_dimensions(avctx, pc->width, pc->height);
70                    did_set_size=1;
71                }
72                frame_rate_index = buf[3] & 0xf;
73                pc->frame_rate.den = avctx->time_base.den = ff_mpeg12_frame_rate_tab[frame_rate_index].num;
74                pc->frame_rate.num = avctx->time_base.num = ff_mpeg12_frame_rate_tab[frame_rate_index].den;
75                bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6);
76                avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO;
77            }
78            break;
79        case EXT_START_CODE:
80            if (bytes_left >= 1) {
81                ext_type = (buf[0] >> 4);
82                switch(ext_type) {
83                case 0x1: /* sequence extension */
84                    if (bytes_left >= 6) {
85                        horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7);
86                        vert_size_ext = (buf[2] >> 5) & 3;
87                        bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1);
88                        frame_rate_ext_n = (buf[5] >> 5) & 3;
89                        frame_rate_ext_d = (buf[5] & 0x1f);
90                        pc->progressive_sequence = buf[1] & (1 << 3);
91                        avctx->has_b_frames= !(buf[5] >> 7);
92
93                        pc->width  |=(horiz_size_ext << 12);
94                        pc->height |=( vert_size_ext << 12);
95                        bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18);
96                        if(did_set_size)
97                            ff_set_dimensions(avctx, pc->width, pc->height);
98                        avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2;
99                        avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1);
100                        avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO;
101                    }
102                    break;
103                case 0x8: /* picture coding extension */
104                    if (bytes_left >= 5) {
105                        top_field_first = buf[3] & (1 << 7);
106                        repeat_first_field = buf[3] & (1 << 1);
107                        progressive_frame = buf[4] & (1 << 7);
108
109                        /* check if we must repeat the frame */
110                        s->repeat_pict = 1;
111                        if (repeat_first_field) {
112                            if (pc->progressive_sequence) {
113                                if (top_field_first)
114                                    s->repeat_pict = 5;
115                                else
116                                    s->repeat_pict = 3;
117                            } else if (progressive_frame) {
118                                s->repeat_pict = 2;
119                            }
120                        }
121
122                        if (!pc->progressive_sequence) {
123                            if (top_field_first)
124                                s->field_order = AV_FIELD_TT;
125                            else
126                                s->field_order = AV_FIELD_BB;
127                        } else
128                            s->field_order = AV_FIELD_PROGRESSIVE;
129                    }
130                    break;
131                }
132            }
133            break;
134        case -1:
135            goto the_end;
136        default:
137            /* we stop parsing when we encounter a slice. It ensures
138               that this function takes a negligible amount of time */
139            if (start_code >= SLICE_MIN_START_CODE &&
140                start_code <= SLICE_MAX_START_CODE)
141                goto the_end;
142            break;
143        }
144    }
145 the_end: ;
146    if (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) {
147        avctx->rc_max_rate = 400*bit_rate;
148    } else if (avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate &&
149               (bit_rate != 0x3FFFF || vbv_delay != 0xFFFF)) {
150        avctx->bit_rate = 400*bit_rate;
151    }
152}
153
154static int mpegvideo_parse(AVCodecParserContext *s,
155                           AVCodecContext *avctx,
156                           const uint8_t **poutbuf, int *poutbuf_size,
157                           const uint8_t *buf, int buf_size)
158{
159    struct MpvParseContext *pc1 = s->priv_data;
160    ParseContext *pc= &pc1->pc;
161    int next;
162
163    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
164        next= buf_size;
165    }else{
166        next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s);
167
168        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
169            *poutbuf = NULL;
170            *poutbuf_size = 0;
171            return buf_size;
172        }
173
174    }
175    /* we have a full frame : we just parse the first few MPEG headers
176       to have the full timing information. The time take by this
177       function should be negligible for uncorrupted streams */
178    mpegvideo_extract_headers(s, avctx, buf, buf_size);
179    av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
180            s->pict_type, (double)avctx->time_base.den / avctx->time_base.num, s->repeat_pict);
181
182    *poutbuf = buf;
183    *poutbuf_size = buf_size;
184    return next;
185}
186
187static int mpegvideo_split(AVCodecContext *avctx,
188                           const uint8_t *buf, int buf_size)
189{
190    int i;
191    uint32_t state= -1;
192    int found=0;
193
194    for(i=0; i<buf_size; i++){
195        state= (state<<8) | buf[i];
196        if(state == 0x1B3){
197            found=1;
198        }else if(found && state != 0x1B5 && state < 0x200 && state >= 0x100)
199            return i-3;
200    }
201    return 0;
202}
203
204static int mpegvideo_parse_init(AVCodecParserContext *s)
205{
206    s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial
207    return 0;
208}
209
210AVCodecParser ff_mpegvideo_parser = {
211    .codec_ids      = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO },
212    .priv_data_size = sizeof(struct MpvParseContext),
213    .parser_init    = mpegvideo_parse_init,
214    .parser_parse   = mpegvideo_parse,
215    .parser_close   = ff_parse_close,
216    .split          = mpegvideo_split,
217};
218