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
26
32 };
33
34
38 {
40 const uint8_t *buf_end = buf + buf_size;
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()
51
52 while (buf < buf_end) {
53 start_code= -1;
55 bytes_left = buf_end -
buf;
56 switch(start_code) {
58 if (bytes_left >= 2) {
60 if (bytes_left >= 4)
61 vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3] >> 3);
62 }
63 break;
65 if (bytes_left >= 7) {
66 pc->
width = (buf[0] << 4) | (buf[1] >> 4);
67 pc->
height = ((buf[1] & 0x0f) << 8) | buf[2];
70 did_set_size=1;
71 }
72 frame_rate_index = buf[3] & 0xf;
75 bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6);
77 }
78 break;
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);
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)
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 */
111 if (repeat_first_field) {
113 if (top_field_first)
115 else
117 } else if (progressive_frame) {
119 }
120 }
121
123 if (top_field_first)
125 else
127 } else
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 */
141 goto the_end;
142 break;
143 }
144 }
145 the_end: ;
149 (bit_rate != 0x3FFFF || vbv_delay != 0xFFFF)) {
151 }
152 }
153
156 const uint8_t **poutbuf,
int *poutbuf_size,
158 {
161 int next;
162
164 next= buf_size;
165 }else{
167
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 */
179 av_dlog(NULL,
"pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
181
183 *poutbuf_size = buf_size;
184 return next;
185 }
186
189 {
190 int i;
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
205 {
207 return 0;
208 }
209
217 };