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path: root/libavfilter/vf_readvitc.c (plain)
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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/pixdesc.h"
31#include "libavutil/timecode.h"
32#include "avfilter.h"
33#include "formats.h"
34#include "internal.h"
35
36#define LINE_DATA_SIZE 9
37
38typedef struct ReadVitcContext {
39 const AVClass *class;
40
41 int scan_max;
42 double thr_b;
43 double thr_w;
44
45 int threshold_black;
46 int threshold_white;
47 int threshold_gray;
48 int grp_width;
49 uint8_t line_data[LINE_DATA_SIZE];
50 char tcbuf[AV_TIMECODE_STR_SIZE];
51} ReadVitcContext;
52
53#define OFFSET(x) offsetof(ReadVitcContext, x)
54#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
55
56static const AVOption readvitc_options[] = {
57 { "scan_max", "maximum line numbers to scan for VITC data", OFFSET(scan_max), AV_OPT_TYPE_INT, {.i64 = 45 }, -1, INT_MAX, FLAGS },
58 { "thr_b", "black color threshold", OFFSET(thr_b), AV_OPT_TYPE_DOUBLE, {.dbl = 0.2 }, 0, 1.0, FLAGS },
59 { "thr_w", "white color threshold", OFFSET(thr_w), AV_OPT_TYPE_DOUBLE, {.dbl = 0.6 }, 0, 1.0, FLAGS },
60 { NULL }
61};
62
63AVFILTER_DEFINE_CLASS(readvitc);
64
65static uint8_t get_vitc_crc( uint8_t *line ) {
66 uint8_t crc;
67
68 crc = 0x01 | (line[0] << 2);
69 crc ^= (line[0] >> 6) | 0x04 | (line[1] << 4);
70 crc ^= (line[1] >> 4) | 0x10 | (line[2] << 6);
71 crc ^= (line[2] >> 2) | 0x40;
72 crc ^= line[3];
73 crc ^= 0x01 | (line[4] << 2);
74 crc ^= (line[4] >> 6) | 0x04 | (line[5] << 4);
75 crc ^= (line[5] >> 4) | 0x10 | (line[6] << 6);
76 crc ^= (line[6] >> 2) | 0x40;
77 crc ^= line[7];
78 crc ^= 0x01;
79 crc = (crc >> 2) | (crc << 6); // rotate byte right by two bits
80 return crc;
81}
82
83static inline uint8_t get_pit_avg3( uint8_t *line, int i ) {
84 return ((line[i-1] + line[i] + line[i+1]) / 3);
85}
86
87static int read_vitc_line( ReadVitcContext *ctx, uint8_t *src, int line_size, int width, int height )
88{
89 uint8_t *scan_line;
90 int grp_index, pit_index;
91 int grp_start_pos;
92 uint8_t pit_value;
93 int x, y, res = 0;
94
95 if (ctx->scan_max >= 0)
96 height = FFMIN(height, ctx->scan_max);
97
98 // scan lines for VITC data, starting from the top
99 for (y = 0; y < height; y++) {
100 scan_line = src;
101 memset(ctx->line_data, 0, LINE_DATA_SIZE);
102 grp_index = 0;
103 x = 0;
104 while ((x < width) && (grp_index < 9)) {
105 // search next sync pattern
106 while ((x < width) && (scan_line[x] < ctx->threshold_white))
107 x++;
108 while ((x < width) && (scan_line[x] > ctx->threshold_black))
109 x++;
110 x = FFMAX(x - ((ctx->grp_width+10) / 20), 1); // step back a half pit
111 grp_start_pos = x;
112 if ((grp_start_pos + ctx->grp_width) > width)
113 break; // not enough pixels for reading a whole pit group
114 pit_value = get_pit_avg3(scan_line, x);
115 if (pit_value < ctx->threshold_white)
116 break; // first sync bit mismatch
117 x = grp_start_pos + ((ctx->grp_width) / 10);
118 pit_value = get_pit_avg3(scan_line, x);
119 if (pit_value > ctx->threshold_black )
120 break; // second sync bit mismatch
121 for (pit_index = 0; pit_index <= 7; pit_index++) {
122 x = grp_start_pos + (((pit_index+2)*ctx->grp_width) / 10);
123 pit_value = get_pit_avg3(scan_line, x);
124 if (pit_value > ctx->threshold_gray)
125 ctx->line_data[grp_index] |= (1 << pit_index);
126 }
127 grp_index++;
128 }
129 if ((grp_index == 9) && (get_vitc_crc(ctx->line_data) == ctx->line_data[8])) {
130 res = 1;
131 break;
132 }
133 src += line_size;
134 }
135
136 return res;
137}
138
139static unsigned bcd2uint(uint8_t high, uint8_t low)
140{
141 if (high > 9 || low > 9)
142 return 0;
143 return 10*high + low;
144}
145
146static char *make_vitc_tc_string(char *buf, uint8_t *line)
147{
148 unsigned hh = bcd2uint(line[7] & 0x03, line[6] & 0x0f); // 6-bit hours
149 unsigned mm = bcd2uint(line[5] & 0x07, line[4] & 0x0f); // 7-bit minutes
150 unsigned ss = bcd2uint(line[3] & 0x07, line[2] & 0x0f); // 7-bit seconds
151 unsigned ff = bcd2uint(line[1] & 0x03, line[0] & 0x0f); // 6-bit frames
152 unsigned drop = (line[1] & 0x04); // 1-bit drop flag
153 snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
154 hh, mm, ss, drop ? ';' : ':', ff);
155 return buf;
156}
157
158static av_cold int init(AVFilterContext *ctx)
159{
160 ReadVitcContext *s = ctx->priv;
161
162 s->threshold_black = s->thr_b * UINT8_MAX;
163 s->threshold_white = s->thr_w * UINT8_MAX;
164 if (s->threshold_black > s->threshold_white) {
165 av_log(ctx, AV_LOG_WARNING, "Black color threshold is higher than white color threshold (%g > %g)\n",
166 s->thr_b, s->thr_w);
167 return AVERROR(EINVAL);
168 }
169 s->threshold_gray = s->threshold_white - ((s->threshold_white - s->threshold_black) / 2);
170 av_log(ctx, AV_LOG_DEBUG, "threshold_black:%d threshold_white:%d threshold_gray:%d\n",
171 s->threshold_black, s->threshold_white, s->threshold_gray);
172
173 return 0;
174}
175
176static int config_props(AVFilterLink *inlink)
177{
178 AVFilterContext *ctx = inlink->dst;
179 ReadVitcContext *s = ctx->priv;
180
181 s->grp_width = inlink->w * 5 / 48;
182 av_log(ctx, AV_LOG_DEBUG, "w:%d h:%d grp_width:%d scan_max:%d\n",
183 inlink->w, inlink->h, s->grp_width, s->scan_max);
184 return 0;
185}
186
187static int query_formats(AVFilterContext *ctx)
188{
189 static const enum AVPixelFormat pixel_fmts[] = {
190 AV_PIX_FMT_GRAY8,
191 AV_PIX_FMT_NV12,
192 AV_PIX_FMT_NV16,
193 AV_PIX_FMT_NV21,
194 AV_PIX_FMT_YUV410P,
195 AV_PIX_FMT_YUV411P,
196 AV_PIX_FMT_YUV420P,
197 AV_PIX_FMT_YUV422P,
198 AV_PIX_FMT_YUV440P,
199 AV_PIX_FMT_YUV444P,
200 AV_PIX_FMT_YUVA420P,
201 AV_PIX_FMT_YUVA422P,
202 AV_PIX_FMT_YUVA444P,
203 AV_PIX_FMT_YUVJ411P,
204 AV_PIX_FMT_YUVJ420P,
205 AV_PIX_FMT_YUVJ422P,
206 AV_PIX_FMT_YUVJ440P,
207 AV_PIX_FMT_YUVJ444P,
208 AV_PIX_FMT_NONE
209 };
210 AVFilterFormats *fmts_list = ff_make_format_list(pixel_fmts);
211 if (!fmts_list)
212 return AVERROR(ENOMEM);
213 return ff_set_common_formats(ctx, fmts_list);
214}
215
216static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
217{
218 AVFilterContext *ctx = inlink->dst;
219 AVFilterLink *outlink = ctx->outputs[0];
220 ReadVitcContext *s = ctx->priv;
221 int found;
222
223 found = read_vitc_line(s, frame->data[0], frame->linesize[0], inlink->w, inlink->h);
224 av_dict_set(avpriv_frame_get_metadatap(frame), "lavfi.readvitc.found", (found ? "1" : "0"), 0);
225 if (found)
226 av_dict_set(avpriv_frame_get_metadatap(frame), "lavfi.readvitc.tc_str", make_vitc_tc_string(s->tcbuf, s->line_data), 0);
227
228 return ff_filter_frame(outlink, frame);
229}
230
231static const AVFilterPad inputs[] = {
232 {
233 .name = "default",
234 .type = AVMEDIA_TYPE_VIDEO,
235 .filter_frame = filter_frame,
236 .config_props = config_props,
237 },
238 { NULL }
239};
240
241static const AVFilterPad outputs[] = {
242 {
243 .name = "default",
244 .type = AVMEDIA_TYPE_VIDEO,
245 },
246 { NULL }
247};
248
249AVFilter ff_vf_readvitc = {
250 .name = "readvitc",
251 .description = NULL_IF_CONFIG_SMALL("Read vertical interval timecode and write it to frame metadata."),
252 .priv_size = sizeof(ReadVitcContext),
253 .priv_class = &readvitc_class,
254 .inputs = inputs,
255 .outputs = outputs,
256 .init = init,
257 .query_formats = query_formats,
258};
259
generated by cgit at 2024-05-17 02:10:50 (GMT)