1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
|
#include "../mpeg3private.h"
#include "../mpeg3protos.h"
#include "mpeg3video.h"
#include <stdlib.h>
#include <string.h>
unsigned int mpeg3bits_next_startcode(mpeg3_bits_t* stream)
{
/* Perform forwards search */
mpeg3bits_byte_align(stream);
/* Perform search */
while((mpeg3bits_showbits32_noptr(stream) >> 8) != MPEG3_PACKET_START_CODE_PREFIX &&
!mpeg3bits_eof(stream))
{
mpeg3bits_getbyte_noptr(stream);
}
return mpeg3bits_showbits32_noptr(stream);
}
/* Line up on the beginning of the next code. */
int mpeg3video_next_code(mpeg3_bits_t* stream, unsigned int code)
{
while(!mpeg3bits_eof(stream) &&
mpeg3bits_showbits32_noptr(stream) != code)
{
mpeg3bits_getbyte_noptr(stream);
}
return mpeg3bits_eof(stream);
}
/* Line up on the beginning of the previous code. */
int mpeg3video_prev_code(mpeg3_bits_t* stream, unsigned int code)
{
while(!mpeg3bits_bof(stream) &&
mpeg3bits_showbits_reverse(stream, 32) != code)
{
mpeg3bits_getbits_reverse(stream, 8);
}
return mpeg3bits_bof(stream);
}
long mpeg3video_goptimecode_to_frame(mpeg3video_t *video)
{
/* printf("mpeg3video_goptimecode_to_frame %d %d %d %d %f\n", */
/* video->gop_timecode.hour, video->gop_timecode.minute, video->gop_timecode.second, video->gop_timecode.frame, video->frame_rate); */
return (long)(video->gop_timecode.hour * 3600 * video->frame_rate +
video->gop_timecode.minute * 60 * video->frame_rate +
video->gop_timecode.second * video->frame_rate +
video->gop_timecode.frame) - 1 - video->first_frame;
}
int mpeg3video_match_refframes(mpeg3video_t *video)
{
unsigned char *dst, *src;
int i, j, size;
for(i = 0; i < 3; i++)
{
if(video->newframe[i])
{
if(video->newframe[i] == video->refframe[i])
{
src = video->refframe[i];
dst = video->oldrefframe[i];
}
else
{
src = video->oldrefframe[i];
dst = video->refframe[i];
}
if(i == 0)
size = video->coded_picture_width * video->coded_picture_height + 32 * video->coded_picture_width;
else
size = video->chrom_width * video->chrom_height + 32 * video->chrom_width;
memcpy(dst, src, size);
}
}
return 0;
}
int mpeg3video_seek(mpeg3video_t *video)
{
long this_gop_start;
int result = 0;
int back_step;
int attempts;
mpeg3_t *file = video->file;
mpeg3_bits_t *vstream = video->vstream;
double percentage;
long frame_number;
int match_refframes = 1;
/* Seek to a percentage */
if(video->percentage_seek >= 0)
{
percentage = video->percentage_seek;
video->percentage_seek = -1;
mpeg3bits_seek_percentage(vstream, percentage);
// Go to previous I-frame
mpeg3bits_start_reverse(vstream);
result = mpeg3video_prev_code(vstream, MPEG3_GOP_START_CODE);
if(!result) mpeg3bits_getbits_reverse(vstream, 32);
mpeg3bits_start_forward(vstream);
if(mpeg3bits_tell_percentage(vstream) < 0) mpeg3bits_seek_percentage(vstream, 0);
// Read up to the correct percentage
result = 0;
while(!result && mpeg3bits_tell_percentage(vstream) < percentage)
{
result = mpeg3video_read_frame_backend(video, 0);
if(match_refframes)
mpeg3video_match_refframes(video);
match_refframes = 0;
}
}
else
/* Seek to a frame */
if(video->frame_seek >= 0)
{
frame_number = video->frame_seek;
video->frame_seek = -1;
if(frame_number < 0) frame_number = 0;
if(frame_number > video->maxframe) frame_number = video->maxframe;
/* Seek to start of file */
if(frame_number < 16)
{
video->repeat_count = video->current_repeat = 0;
mpeg3bits_seek_start(vstream);
video->framenum = 0;
result = mpeg3video_drop_frames(video, frame_number - video->framenum);
}
else
{
/* Seek to an I frame. */
if((frame_number < video->framenum || frame_number - video->framenum > MPEG3_SEEK_THRESHOLD))
{
/* Elementary stream */
if(file->is_video_stream)
{
mpeg3_t *file = video->file;
mpeg3_vtrack_t *track = video->track;
long byte = (long)((float)(mpeg3demuxer_total_bytes(vstream->demuxer) /
track->total_frames) *
frame_number);
long minimum = 65535;
int done = 0;
//printf("seek elementary %d\n", frame_number);
/* Get GOP just before frame */
do
{
result = mpeg3bits_seek_byte(vstream, byte);
mpeg3bits_start_reverse(vstream);
if(!result) result = mpeg3video_prev_code(vstream, MPEG3_GOP_START_CODE);
mpeg3bits_start_forward(vstream);
mpeg3bits_getbits(vstream, 8);
if(!result) result = mpeg3video_getgophdr(video);
this_gop_start = mpeg3video_goptimecode_to_frame(video);
//printf("wanted %ld guessed %ld byte %ld result %d\n", frame_number, this_gop_start, byte, result);
if(labs(this_gop_start - frame_number) >= labs(minimum))
done = 1;
else
{
minimum = this_gop_start - frame_number;
byte += (long)((float)(frame_number - this_gop_start) *
(float)(mpeg3demuxer_total_bytes(vstream->demuxer) /
track->total_frames));
if(byte < 0) byte = 0;
}
}while(!result && !done);
//printf("wanted %d guessed %d\n", frame_number, this_gop_start);
if(!result)
{
video->framenum = this_gop_start;
result = mpeg3video_drop_frames(video, frame_number - video->framenum);
}
}
else
/* System stream */
{
mpeg3bits_seek_time(vstream, (double)frame_number / video->frame_rate);
percentage = mpeg3bits_tell_percentage(vstream);
//printf("seek frame %ld percentage %f byte %ld\n", frame_number, percentage, mpeg3bits_tell(vstream));
mpeg3bits_start_reverse(vstream);
mpeg3video_prev_code(vstream, MPEG3_GOP_START_CODE);
mpeg3bits_getbits_reverse(vstream, 32);
mpeg3bits_start_forward(vstream);
//printf("seek system 1 %f\n", (double)frame_number / video->frame_rate);
while(!result && mpeg3bits_tell_percentage(vstream) < percentage)
{
result = mpeg3video_read_frame_backend(video, 0);
if(match_refframes)
mpeg3video_match_refframes(video);
//printf("seek system 2 %f %f\n", mpeg3bits_tell_percentage(vstream) / percentage);
match_refframes = 0;
}
//printf("seek system 3 %f\n", (double)frame_number / video->frame_rate);
}
video->framenum = frame_number;
}
else
// Drop frames
{
mpeg3video_drop_frames(video, frame_number - video->framenum);
}
}
}
return result;
}
int mpeg3video_drop_frames(mpeg3video_t *video, long frames)
{
int result = 0;
long frame_number = video->framenum + frames;
/* Read the selected number of frames and skip b-frames */
while(!result && frame_number > video->framenum)
{
result = mpeg3video_read_frame_backend(video, frame_number - video->framenum);
}
return result;
}
|
