FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavfilter/vf_readvitc.c
Date: 2025-10-24 21:16:34
Exec Total Coverage
Lines: 84 89 94.4%
Functions: 8 8 100.0%
Branches: 33 42 78.6%
Line Branch Exec Source
1 /*
2 * Copyright (c) 2016 Tobias Rapp
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * Filter for reading the vertical interval timecode (VITC).
24 * See also https://en.wikipedia.org/wiki/Vertical_interval_timecode
25 */
26
27 #include "libavutil/common.h"
28 #include "libavutil/internal.h"
29 #include "libavutil/opt.h"
30 #include "libavutil/timecode.h"
31 #include "avfilter.h"
32 #include "filters.h"
33 #include "video.h"
34
35 #define LINE_DATA_SIZE 9
36
37 typedef struct ReadVitcContext {
38 const AVClass *class;
39
40 int scan_max;
41 double thr_b;
42 double thr_w;
43
44 int threshold_black;
45 int threshold_white;
46 int threshold_gray;
47 int grp_width;
48 uint8_t line_data[LINE_DATA_SIZE];
49 char tcbuf[AV_TIMECODE_STR_SIZE];
50 } ReadVitcContext;
51
52 #define OFFSET(x) offsetof(ReadVitcContext, x)
53 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
54
55 static const AVOption readvitc_options[] = {
56 { "scan_max", "maximum line numbers to scan for VITC data", OFFSET(scan_max), AV_OPT_TYPE_INT, {.i64 = 45 }, -1, INT_MAX, FLAGS },
57 { "thr_b", "black color threshold", OFFSET(thr_b), AV_OPT_TYPE_DOUBLE, {.dbl = 0.2 }, 0, 1.0, FLAGS },
58 { "thr_w", "white color threshold", OFFSET(thr_w), AV_OPT_TYPE_DOUBLE, {.dbl = 0.6 }, 0, 1.0, FLAGS },
59 { NULL }
60 };
61
62 AVFILTER_DEFINE_CLASS(readvitc);
63
64 8 static uint8_t get_vitc_crc( uint8_t *line ) {
65 uint8_t crc;
66
67 8 crc = 0x01 | (line[0] << 2);
68 8 crc ^= (line[0] >> 6) | 0x04 | (line[1] << 4);
69 8 crc ^= (line[1] >> 4) | 0x10 | (line[2] << 6);
70 8 crc ^= (line[2] >> 2) | 0x40;
71 8 crc ^= line[3];
72 8 crc ^= 0x01 | (line[4] << 2);
73 8 crc ^= (line[4] >> 6) | 0x04 | (line[5] << 4);
74 8 crc ^= (line[5] >> 4) | 0x10 | (line[6] << 6);
75 8 crc ^= (line[6] >> 2) | 0x40;
76 8 crc ^= line[7];
77 8 crc ^= 0x01;
78 8 crc = (crc >> 2) | (crc << 6); // rotate byte right by two bits
79 8 return crc;
80 }
81
82 720 static inline uint8_t get_pit_avg3( uint8_t *line, int i ) {
83 720 return ((line[i-1] + line[i] + line[i+1]) / 3);
84 }
85
86 10 static int read_vitc_line( ReadVitcContext *ctx, uint8_t *src, int line_size, int width, int height )
87 {
88 uint8_t *scan_line;
89 int grp_index, pit_index;
90 int grp_start_pos;
91 uint8_t pit_value;
92 10 int x, y, res = 0;
93
94
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 10 if (ctx->scan_max >= 0)
95 10 height = FFMIN(height, ctx->scan_max);
96
97 // scan lines for VITC data, starting from the top
98
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 292 for (y = 0; y < height; y++) {
99 290 scan_line = src;
100 290 memset(ctx->line_data, 0, LINE_DATA_SIZE);
101 290 grp_index = 0;
102 290 x = 0;
103
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 362 while ((x < width) && (grp_index < 9)) {
104 // search next sync pattern
105
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 200375 while ((x < width) && (scan_line[x] < ctx->threshold_white))
106 200021 x++;
107
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 4392 while ((x < width) && (scan_line[x] > ctx->threshold_black))
108 4038 x++;
109 354 x = FFMAX(x - ((ctx->grp_width+10) / 20), 1); // step back a half pit
110 354 grp_start_pos = x;
111
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 354 if ((grp_start_pos + ctx->grp_width) > width)
112 282 break; // not enough pixels for reading a whole pit group
113 72 pit_value = get_pit_avg3(scan_line, x);
114
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 72 if (pit_value < ctx->threshold_white)
115 ✗ break; // first sync bit mismatch
116 72 x = grp_start_pos + ((ctx->grp_width) / 10);
117 72 pit_value = get_pit_avg3(scan_line, x);
118
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 72 if (pit_value > ctx->threshold_black )
119 ✗ break; // second sync bit mismatch
120
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 648 for (pit_index = 0; pit_index <= 7; pit_index++) {
121 576 x = grp_start_pos + (((pit_index+2)*ctx->grp_width) / 10);
122 576 pit_value = get_pit_avg3(scan_line, x);
123
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 576 if (pit_value > ctx->threshold_gray)
124 146 ctx->line_data[grp_index] |= (1 << pit_index);
125 }
126 72 grp_index++;
127 }
128
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 290 if ((grp_index == 9) && (get_vitc_crc(ctx->line_data) == ctx->line_data[8])) {
129 8 res = 1;
130 8 break;
131 }
132 282 src += line_size;
133 }
134
135 10 return res;
136 }
137
138 32 static unsigned bcd2uint(uint8_t high, uint8_t low)
139 {
140
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 32 if (high > 9 || low > 9)
141 ✗ return 0;
142 32 return 10*high + low;
143 }
144
145 8 static char *make_vitc_tc_string(char *buf, uint8_t *line)
146 {
147 8 unsigned hh = bcd2uint(line[7] & 0x03, line[6] & 0x0f); // 6-bit hours
148 8 unsigned mm = bcd2uint(line[5] & 0x07, line[4] & 0x0f); // 7-bit minutes
149 8 unsigned ss = bcd2uint(line[3] & 0x07, line[2] & 0x0f); // 7-bit seconds
150 8 unsigned ff = bcd2uint(line[1] & 0x03, line[0] & 0x0f); // 6-bit frames
151 8 unsigned drop = (line[1] & 0x04); // 1-bit drop flag
152
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 8 snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
153 hh, mm, ss, drop ? ';' : ':', ff);
154 8 return buf;
155 }
156
157 2 static av_cold int init(AVFilterContext *ctx)
158 {
159 2 ReadVitcContext *s = ctx->priv;
160
161 2 s->threshold_black = s->thr_b * UINT8_MAX;
162 2 s->threshold_white = s->thr_w * UINT8_MAX;
163
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 2 if (s->threshold_black > s->threshold_white) {
164 ✗ av_log(ctx, AV_LOG_WARNING, "Black color threshold is higher than white color threshold (%g > %g)\n",
165 s->thr_b, s->thr_w);
166 ✗ return AVERROR(EINVAL);
167 }
168 2 s->threshold_gray = s->threshold_white - ((s->threshold_white - s->threshold_black) / 2);
169 2 av_log(ctx, AV_LOG_DEBUG, "threshold_black:%d threshold_white:%d threshold_gray:%d\n",
170 s->threshold_black, s->threshold_white, s->threshold_gray);
171
172 2 return 0;
173 }
174
175 2 static int config_props(AVFilterLink *inlink)
176 {
177 2 AVFilterContext *ctx = inlink->dst;
178 2 ReadVitcContext *s = ctx->priv;
179
180 2 s->grp_width = inlink->w * 5 / 48;
181 2 av_log(ctx, AV_LOG_DEBUG, "w:%d h:%d grp_width:%d scan_max:%d\n",
182 inlink->w, inlink->h, s->grp_width, s->scan_max);
183 2 return 0;
184 }
185
186 static const enum AVPixelFormat pixel_fmts[] = {
187 AV_PIX_FMT_GRAY8,
188 AV_PIX_FMT_NV12,
189 AV_PIX_FMT_NV16,
190 AV_PIX_FMT_NV21,
191 AV_PIX_FMT_YUV410P,
192 AV_PIX_FMT_YUV411P,
193 AV_PIX_FMT_YUV420P,
194 AV_PIX_FMT_YUV422P,
195 AV_PIX_FMT_YUV440P,
196 AV_PIX_FMT_YUV444P,
197 AV_PIX_FMT_YUVA420P,
198 AV_PIX_FMT_YUVA422P,
199 AV_PIX_FMT_YUVA444P,
200 AV_PIX_FMT_YUVJ411P,
201 AV_PIX_FMT_YUVJ420P,
202 AV_PIX_FMT_YUVJ422P,
203 AV_PIX_FMT_YUVJ440P,
204 AV_PIX_FMT_YUVJ444P,
205 AV_PIX_FMT_NONE
206 };
207
208 10 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
209 {
210 10 AVFilterContext *ctx = inlink->dst;
211 10 AVFilterLink *outlink = ctx->outputs[0];
212 10 ReadVitcContext *s = ctx->priv;
213 int found;
214
215 10 found = read_vitc_line(s, frame->data[0], frame->linesize[0], inlink->w, inlink->h);
216
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 10 av_dict_set(&frame->metadata, "lavfi.readvitc.found", (found ? "1" : "0"), 0);
217
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 10 if (found)
218 8 av_dict_set(&frame->metadata, "lavfi.readvitc.tc_str", make_vitc_tc_string(s->tcbuf, s->line_data), 0);
219
220 10 return ff_filter_frame(outlink, frame);
221 }
222
223 static const AVFilterPad inputs[] = {
224 {
225 .name = "default",
226 .type = AVMEDIA_TYPE_VIDEO,
227 .filter_frame = filter_frame,
228 .config_props = config_props,
229 },
230 };
231
232 const FFFilter ff_vf_readvitc = {
233 .p.name = "readvitc",
234 .p.description = NULL_IF_CONFIG_SMALL("Read vertical interval timecode and write it to frame metadata."),
235 .p.priv_class = &readvitc_class,
236 .p.flags = AVFILTER_FLAG_METADATA_ONLY,
237 .priv_size = sizeof(ReadVitcContext),
238 FILTER_INPUTS(inputs),
239 FILTER_OUTPUTS(ff_video_default_filterpad),
240 FILTER_PIXFMTS_ARRAY(pixel_fmts),
241 .init = init,
242 };
243