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
234
235
236
237
238
239
240
241
242
|
/*
* Copyright (c) 2016 Tobias Rapp
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Filter for reading the vertical interval timecode (VITC).
* See also https://en.wikipedia.org/wiki/Vertical_interval_timecode
*/
#include "libavutil/common.h"
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "libavutil/timecode.h"
#include "avfilter.h"
#include "filters.h"
#include "video.h"
#define LINE_DATA_SIZE 9
typedef struct ReadVitcContext {
const AVClass *class;
int scan_max;
double thr_b;
double thr_w;
int threshold_black;
int threshold_white;
int threshold_gray;
int grp_width;
uint8_t line_data[LINE_DATA_SIZE];
char tcbuf[AV_TIMECODE_STR_SIZE];
} ReadVitcContext;
#define OFFSET(x) offsetof(ReadVitcContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption readvitc_options[] = {
{ "scan_max", "maximum line numbers to scan for VITC data", OFFSET(scan_max), AV_OPT_TYPE_INT, {.i64 = 45 }, -1, INT_MAX, FLAGS },
{ "thr_b", "black color threshold", OFFSET(thr_b), AV_OPT_TYPE_DOUBLE, {.dbl = 0.2 }, 0, 1.0, FLAGS },
{ "thr_w", "white color threshold", OFFSET(thr_w), AV_OPT_TYPE_DOUBLE, {.dbl = 0.6 }, 0, 1.0, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(readvitc);
static uint8_t get_vitc_crc( uint8_t *line ) {
uint8_t crc;
crc = 0x01 | (line[0] << 2);
crc ^= (line[0] >> 6) | 0x04 | (line[1] << 4);
crc ^= (line[1] >> 4) | 0x10 | (line[2] << 6);
crc ^= (line[2] >> 2) | 0x40;
crc ^= line[3];
crc ^= 0x01 | (line[4] << 2);
crc ^= (line[4] >> 6) | 0x04 | (line[5] << 4);
crc ^= (line[5] >> 4) | 0x10 | (line[6] << 6);
crc ^= (line[6] >> 2) | 0x40;
crc ^= line[7];
crc ^= 0x01;
crc = (crc >> 2) | (crc << 6); // rotate byte right by two bits
return crc;
}
static inline uint8_t get_pit_avg3( uint8_t *line, int i ) {
return ((line[i-1] + line[i] + line[i+1]) / 3);
}
static int read_vitc_line( ReadVitcContext *ctx, uint8_t *src, int line_size, int width, int height )
{
uint8_t *scan_line;
int grp_index, pit_index;
int grp_start_pos;
uint8_t pit_value;
int x, y, res = 0;
if (ctx->scan_max >= 0)
height = FFMIN(height, ctx->scan_max);
// scan lines for VITC data, starting from the top
for (y = 0; y < height; y++) {
scan_line = src;
memset(ctx->line_data, 0, LINE_DATA_SIZE);
grp_index = 0;
x = 0;
while ((x < width) && (grp_index < 9)) {
// search next sync pattern
while ((x < width) && (scan_line[x] < ctx->threshold_white))
x++;
while ((x < width) && (scan_line[x] > ctx->threshold_black))
x++;
x = FFMAX(x - ((ctx->grp_width+10) / 20), 1); // step back a half pit
grp_start_pos = x;
if ((grp_start_pos + ctx->grp_width) > width)
break; // not enough pixels for reading a whole pit group
pit_value = get_pit_avg3(scan_line, x);
if (pit_value < ctx->threshold_white)
break; // first sync bit mismatch
x = grp_start_pos + ((ctx->grp_width) / 10);
pit_value = get_pit_avg3(scan_line, x);
if (pit_value > ctx->threshold_black )
break; // second sync bit mismatch
for (pit_index = 0; pit_index <= 7; pit_index++) {
x = grp_start_pos + (((pit_index+2)*ctx->grp_width) / 10);
pit_value = get_pit_avg3(scan_line, x);
if (pit_value > ctx->threshold_gray)
ctx->line_data[grp_index] |= (1 << pit_index);
}
grp_index++;
}
if ((grp_index == 9) && (get_vitc_crc(ctx->line_data) == ctx->line_data[8])) {
res = 1;
break;
}
src += line_size;
}
return res;
}
static unsigned bcd2uint(uint8_t high, uint8_t low)
{
if (high > 9 || low > 9)
return 0;
return 10*high + low;
}
static char *make_vitc_tc_string(char *buf, uint8_t *line)
{
unsigned hh = bcd2uint(line[7] & 0x03, line[6] & 0x0f); // 6-bit hours
unsigned mm = bcd2uint(line[5] & 0x07, line[4] & 0x0f); // 7-bit minutes
unsigned ss = bcd2uint(line[3] & 0x07, line[2] & 0x0f); // 7-bit seconds
unsigned ff = bcd2uint(line[1] & 0x03, line[0] & 0x0f); // 6-bit frames
unsigned drop = (line[1] & 0x04); // 1-bit drop flag
snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
hh, mm, ss, drop ? ';' : ':', ff);
return buf;
}
static av_cold int init(AVFilterContext *ctx)
{
ReadVitcContext *s = ctx->priv;
s->threshold_black = s->thr_b * UINT8_MAX;
s->threshold_white = s->thr_w * UINT8_MAX;
if (s->threshold_black > s->threshold_white) {
av_log(ctx, AV_LOG_WARNING, "Black color threshold is higher than white color threshold (%g > %g)\n",
s->thr_b, s->thr_w);
return AVERROR(EINVAL);
}
s->threshold_gray = s->threshold_white - ((s->threshold_white - s->threshold_black) / 2);
av_log(ctx, AV_LOG_DEBUG, "threshold_black:%d threshold_white:%d threshold_gray:%d\n",
s->threshold_black, s->threshold_white, s->threshold_gray);
return 0;
}
static int config_props(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
ReadVitcContext *s = ctx->priv;
s->grp_width = inlink->w * 5 / 48;
av_log(ctx, AV_LOG_DEBUG, "w:%d h:%d grp_width:%d scan_max:%d\n",
inlink->w, inlink->h, s->grp_width, s->scan_max);
return 0;
}
static const enum AVPixelFormat pixel_fmts[] = {
AV_PIX_FMT_GRAY8,
AV_PIX_FMT_NV12,
AV_PIX_FMT_NV16,
AV_PIX_FMT_NV21,
AV_PIX_FMT_YUV410P,
AV_PIX_FMT_YUV411P,
AV_PIX_FMT_YUV420P,
AV_PIX_FMT_YUV422P,
AV_PIX_FMT_YUV440P,
AV_PIX_FMT_YUV444P,
AV_PIX_FMT_YUVA420P,
AV_PIX_FMT_YUVA422P,
AV_PIX_FMT_YUVA444P,
AV_PIX_FMT_YUVJ411P,
AV_PIX_FMT_YUVJ420P,
AV_PIX_FMT_YUVJ422P,
AV_PIX_FMT_YUVJ440P,
AV_PIX_FMT_YUVJ444P,
AV_PIX_FMT_NONE
};
static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
ReadVitcContext *s = ctx->priv;
int found;
found = read_vitc_line(s, frame->data[0], frame->linesize[0], inlink->w, inlink->h);
av_dict_set(&frame->metadata, "lavfi.readvitc.found", (found ? "1" : "0"), 0);
if (found)
av_dict_set(&frame->metadata, "lavfi.readvitc.tc_str", make_vitc_tc_string(s->tcbuf, s->line_data), 0);
return ff_filter_frame(outlink, frame);
}
static const AVFilterPad inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
.config_props = config_props,
},
};
const AVFilter ff_vf_readvitc = {
.name = "readvitc",
.description = NULL_IF_CONFIG_SMALL("Read vertical interval timecode and write it to frame metadata."),
.priv_size = sizeof(ReadVitcContext),
.priv_class = &readvitc_class,
.flags = AVFILTER_FLAG_METADATA_ONLY,
FILTER_INPUTS(inputs),
FILTER_OUTPUTS(ff_video_default_filterpad),
FILTER_PIXFMTS_ARRAY(pixel_fmts),
.init = init,
};
|
