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path: root/libavfilter/vf_readeia608.c (plain)
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1/*
2 * Copyright (c) 2017 Paul B Mahol
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 closed captioning data (EIA-608).
24 * See also https://en.wikipedia.org/wiki/EIA-608
25 */
26
27#include <string.h>
28
29#include "libavutil/internal.h"
30#include "libavutil/opt.h"
31#include "libavutil/pixdesc.h"
32#include "libavutil/timestamp.h"
33
34#include "avfilter.h"
35#include "formats.h"
36#include "internal.h"
37#include "video.h"
38
39#define FALL 0
40#define RISE 1
41
42typedef struct ReadEIA608Context {
43 const AVClass *class;
44 int start, end;
45 int min_range;
46 int max_peak_diff;
47 int max_period_diff;
48 int max_start_diff;
49 int nb_found;
50 int white;
51 int black;
52 float mpd, mhd, msd, mac, spw, bhd, wth, bth;
53 int chp;
54} ReadEIA608Context;
55
56#define OFFSET(x) offsetof(ReadEIA608Context, x)
57#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
58
59static const AVOption readeia608_options[] = {
60 { "scan_min", "set from which line to scan for codes", OFFSET(start), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
61 { "scan_max", "set to which line to scan for codes", OFFSET(end), AV_OPT_TYPE_INT, {.i64=29}, 0, INT_MAX, FLAGS },
62 { "mac", "set minimal acceptable amplitude change for sync codes detection", OFFSET(mac), AV_OPT_TYPE_FLOAT, {.dbl=.2}, 0.001, 1, FLAGS },
63 { "spw", "set ratio of width reserved for sync code detection", OFFSET(spw), AV_OPT_TYPE_FLOAT, {.dbl=.27}, 0.1, 0.7, FLAGS },
64 { "mhd", "set max peaks height difference for sync code detection", OFFSET(mhd), AV_OPT_TYPE_FLOAT, {.dbl=.1}, 0, 0.5, FLAGS },
65 { "mpd", "set max peaks period difference for sync code detection", OFFSET(mpd), AV_OPT_TYPE_FLOAT, {.dbl=.1}, 0, 0.5, FLAGS },
66 { "msd", "set first two max start code bits differences", OFFSET(msd), AV_OPT_TYPE_FLOAT, {.dbl=.02}, 0, 0.5, FLAGS },
67 { "bhd", "set min ratio of bits height compared to 3rd start code bit", OFFSET(bhd), AV_OPT_TYPE_FLOAT, {.dbl=.75}, 0.01, 1, FLAGS },
68 { "th_w", "set white color threshold", OFFSET(wth), AV_OPT_TYPE_FLOAT, {.dbl=.35}, 0.1, 1, FLAGS },
69 { "th_b", "set black color threshold", OFFSET(bth), AV_OPT_TYPE_FLOAT, {.dbl=.15}, 0, 0.5, FLAGS },
70 { "chp", "check and apply parity bit", OFFSET(chp), AV_OPT_TYPE_BOOL, {.i64= 0}, 0, 1, FLAGS },
71 { NULL }
72};
73
74AVFILTER_DEFINE_CLASS(readeia608);
75
76static int query_formats(AVFilterContext *ctx)
77{
78 static const enum AVPixelFormat pixel_fmts[] = {
79 AV_PIX_FMT_GRAY8,
80 AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
81 AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
82 AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
83 AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
84 AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
85 AV_PIX_FMT_YUVJ411P,
86 AV_PIX_FMT_NONE
87 };
88 AVFilterFormats *formats = ff_make_format_list(pixel_fmts);
89 if (!formats)
90 return AVERROR(ENOMEM);
91 return ff_set_common_formats(ctx, formats);
92}
93
94static int config_input(AVFilterLink *inlink)
95{
96 const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
97 AVFilterContext *ctx = inlink->dst;
98 ReadEIA608Context *s = ctx->priv;
99 int depth = desc->comp[0].depth;
100
101 if (s->end >= inlink->h) {
102 av_log(ctx, AV_LOG_WARNING, "Last line to scan too large, clipping.\n");
103 s->end = inlink->h - 1;
104 }
105
106 if (s->start > s->end) {
107 av_log(ctx, AV_LOG_ERROR, "Invalid range.\n");
108 return AVERROR(EINVAL);
109 }
110
111 s->min_range = s->mac * ((1 << depth) - 1);
112 s->max_peak_diff = s->mhd * ((1 << depth) - 1);
113 s->max_period_diff = s->mpd * ((1 << depth) - 1);
114 s->max_start_diff = s->msd * ((1 << depth) - 1);
115 s->white = s->wth * ((1 << depth) - 1);
116 s->black = s->bth * ((1 << depth) - 1);
117
118 return 0;
119}
120
121static void extract_line(AVFilterContext *ctx, AVFilterLink *inlink, AVFrame *in, int line)
122{
123 ReadEIA608Context *s = ctx->priv;
124 int max = 0, min = INT_MAX;
125 int i, ch, range = 0;
126 const uint8_t *src;
127 uint16_t clock[8][2] = { { 0 } };
128 const int sync_width = s->spw * in->width;
129 int last = 0, peaks = 0, max_peak_diff = 0, dir = RISE;
130 const int width_per_bit = (in->width - sync_width) / 19;
131 uint8_t byte[2] = { 0 };
132 int s1, s2, s3, parity;
133
134 src = &in->data[0][line * in->linesize[0]];
135 for (i = 0; i < sync_width; i++) {
136 max = FFMAX(max, src[i]);
137 min = FFMIN(min, src[i]);
138 }
139
140 range = max - min;
141 if (range < s->min_range)
142 return;
143
144 for (i = 0; i < sync_width; i++) {
145 int Y = src[i];
146
147 if (dir == RISE) {
148 if (Y < last) {
149 dir = FALL;
150 if (last >= s->white) {
151 clock[peaks][0] = last;
152 clock[peaks][1] = i;
153 peaks++;
154 if (peaks > 7)
155 break;
156 }
157 }
158 } else if (dir == FALL) {
159 if (Y > last && last <= s->black) {
160 dir = RISE;
161 }
162 }
163 last = Y;
164 }
165
166 if (peaks != 7)
167 return;
168
169 for (i = 1; i < 7; i++)
170 max_peak_diff = FFMAX(max_peak_diff, FFABS(clock[i][0] - clock[i-1][0]));
171
172 if (max_peak_diff > s->max_peak_diff)
173 return;
174
175 max = 0; min = INT_MAX;
176 for (i = 1; i < 7; i++) {
177 max = FFMAX(max, FFABS(clock[i][1] - clock[i-1][1]));
178 min = FFMIN(min, FFABS(clock[i][1] - clock[i-1][1]));
179 }
180
181 range = max - min;
182 if (range > s->max_period_diff)
183 return;
184
185 s1 = src[sync_width + width_per_bit * 0 + width_per_bit / 2];
186 s2 = src[sync_width + width_per_bit * 1 + width_per_bit / 2];
187 s3 = src[sync_width + width_per_bit * 2 + width_per_bit / 2];
188
189 if (FFABS(s1 - s2) > s->max_start_diff || s1 > s->black || s2 > s->black || s3 < s->white)
190 return;
191
192 for (ch = 0; ch < 2; ch++) {
193 for (parity = 0, i = 0; i < 8; i++) {
194 int b = src[sync_width + width_per_bit * (i + 3 + 8 * ch) + width_per_bit / 2];
195
196 if (b - s1 > (s3 - s1) * s->bhd) {
197 b = 1;
198 parity++;
199 } else {
200 b = 0;
201 }
202 byte[ch] |= b << i;
203 }
204
205 if (s->chp) {
206 if (!(parity & 1)) {
207 byte[ch] = 0;
208 }
209 }
210 }
211
212 {
213 uint8_t key[128], value[128];
214
215 snprintf(key, sizeof(key), "lavfi.readeia608.%d.cc", s->nb_found);
216 snprintf(value, sizeof(value), "0x%02X%02X", byte[0], byte[1]);
217 av_dict_set(avpriv_frame_get_metadatap(in), key, value, 0);
218
219 snprintf(key, sizeof(key), "lavfi.readeia608.%d.line", s->nb_found);
220 snprintf(value, sizeof(value), "%d", line);
221 av_dict_set(avpriv_frame_get_metadatap(in), key, value, 0);
222 }
223
224 s->nb_found++;
225}
226
227static int filter_frame(AVFilterLink *inlink, AVFrame *in)
228{
229 AVFilterContext *ctx = inlink->dst;
230 AVFilterLink *outlink = ctx->outputs[0];
231 ReadEIA608Context *s = ctx->priv;
232 int i;
233
234 s->nb_found = 0;
235 for (i = s->start; i <= s->end; i++)
236 extract_line(ctx, inlink, in, i);
237
238 return ff_filter_frame(outlink, in);
239}
240
241static const AVFilterPad readeia608_inputs[] = {
242 {
243 .name = "default",
244 .type = AVMEDIA_TYPE_VIDEO,
245 .filter_frame = filter_frame,
246 .config_props = config_input,
247 },
248 { NULL }
249};
250
251static const AVFilterPad readeia608_outputs[] = {
252 {
253 .name = "default",
254 .type = AVMEDIA_TYPE_VIDEO,
255 },
256 { NULL }
257};
258
259AVFilter ff_vf_readeia608 = {
260 .name = "readeia608",
261 .description = NULL_IF_CONFIG_SMALL("Read EIA-608 Closed Caption codes from input video and write them to frame metadata."),
262 .priv_size = sizeof(ReadEIA608Context),
263 .priv_class = &readeia608_class,
264 .query_formats = query_formats,
265 .inputs = readeia608_inputs,
266 .outputs = readeia608_outputs,
267 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
268};
269
generated by cgit at 2024-05-17 06:11:17 (GMT)