269 lines
8.8 KiB
C
269 lines
8.8 KiB
C
/*
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* Copyright (c) 2017 Paul B Mahol
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Filter for reading closed captioning data (EIA-608).
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* See also https://en.wikipedia.org/wiki/EIA-608
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*/
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#include <string.h>
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#include "libavutil/internal.h"
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#include "libavutil/opt.h"
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#include "libavutil/pixdesc.h"
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#include "libavutil/timestamp.h"
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#include "avfilter.h"
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#include "formats.h"
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#include "internal.h"
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#include "video.h"
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#define FALL 0
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#define RISE 1
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typedef struct ReadEIA608Context {
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const AVClass *class;
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int start, end;
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int min_range;
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int max_peak_diff;
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int max_period_diff;
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int max_start_diff;
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int nb_found;
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int white;
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int black;
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float mpd, mhd, msd, mac, spw, bhd, wth, bth;
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int chp;
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} ReadEIA608Context;
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#define OFFSET(x) offsetof(ReadEIA608Context, x)
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#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
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static const AVOption readeia608_options[] = {
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{ "scan_min", "set from which line to scan for codes", OFFSET(start), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
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{ "scan_max", "set to which line to scan for codes", OFFSET(end), AV_OPT_TYPE_INT, {.i64=29}, 0, INT_MAX, FLAGS },
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{ "mac", "set minimal acceptable amplitude change for sync codes detection", OFFSET(mac), AV_OPT_TYPE_FLOAT, {.dbl=.2}, 0.001, 1, FLAGS },
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{ "spw", "set ratio of width reserved for sync code detection", OFFSET(spw), AV_OPT_TYPE_FLOAT, {.dbl=.27}, 0.1, 0.7, FLAGS },
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{ "mhd", "set max peaks height difference for sync code detection", OFFSET(mhd), AV_OPT_TYPE_FLOAT, {.dbl=.1}, 0, 0.5, FLAGS },
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{ "mpd", "set max peaks period difference for sync code detection", OFFSET(mpd), AV_OPT_TYPE_FLOAT, {.dbl=.1}, 0, 0.5, FLAGS },
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{ "msd", "set first two max start code bits differences", OFFSET(msd), AV_OPT_TYPE_FLOAT, {.dbl=.02}, 0, 0.5, FLAGS },
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{ "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 },
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{ "th_w", "set white color threshold", OFFSET(wth), AV_OPT_TYPE_FLOAT, {.dbl=.35}, 0.1, 1, FLAGS },
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{ "th_b", "set black color threshold", OFFSET(bth), AV_OPT_TYPE_FLOAT, {.dbl=.15}, 0, 0.5, FLAGS },
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{ "chp", "check and apply parity bit", OFFSET(chp), AV_OPT_TYPE_BOOL, {.i64= 0}, 0, 1, FLAGS },
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{ NULL }
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};
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AVFILTER_DEFINE_CLASS(readeia608);
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static int query_formats(AVFilterContext *ctx)
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{
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static const enum AVPixelFormat pixel_fmts[] = {
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AV_PIX_FMT_GRAY8,
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AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
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AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
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AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
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AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
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AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
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AV_PIX_FMT_YUVJ411P,
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AV_PIX_FMT_NONE
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};
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AVFilterFormats *formats = ff_make_format_list(pixel_fmts);
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if (!formats)
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return AVERROR(ENOMEM);
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return ff_set_common_formats(ctx, formats);
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}
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static int config_input(AVFilterLink *inlink)
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{
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const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
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AVFilterContext *ctx = inlink->dst;
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ReadEIA608Context *s = ctx->priv;
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int depth = desc->comp[0].depth;
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if (s->end >= inlink->h) {
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av_log(ctx, AV_LOG_WARNING, "Last line to scan too large, clipping.\n");
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s->end = inlink->h - 1;
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}
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if (s->start > s->end) {
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av_log(ctx, AV_LOG_ERROR, "Invalid range.\n");
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return AVERROR(EINVAL);
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}
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s->min_range = s->mac * ((1 << depth) - 1);
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s->max_peak_diff = s->mhd * ((1 << depth) - 1);
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s->max_period_diff = s->mpd * ((1 << depth) - 1);
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s->max_start_diff = s->msd * ((1 << depth) - 1);
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s->white = s->wth * ((1 << depth) - 1);
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s->black = s->bth * ((1 << depth) - 1);
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return 0;
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}
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static void extract_line(AVFilterContext *ctx, AVFilterLink *inlink, AVFrame *in, int line)
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{
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ReadEIA608Context *s = ctx->priv;
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int max = 0, min = INT_MAX;
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int i, ch, range = 0;
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const uint8_t *src;
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uint16_t clock[8][2] = { { 0 } };
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const int sync_width = s->spw * in->width;
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int last = 0, peaks = 0, max_peak_diff = 0, dir = RISE;
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const int width_per_bit = (in->width - sync_width) / 19;
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uint8_t byte[2] = { 0 };
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int s1, s2, s3, parity;
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src = &in->data[0][line * in->linesize[0]];
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for (i = 0; i < sync_width; i++) {
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max = FFMAX(max, src[i]);
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min = FFMIN(min, src[i]);
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}
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range = max - min;
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if (range < s->min_range)
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return;
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for (i = 0; i < sync_width; i++) {
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int Y = src[i];
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if (dir == RISE) {
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if (Y < last) {
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dir = FALL;
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if (last >= s->white) {
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clock[peaks][0] = last;
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clock[peaks][1] = i;
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peaks++;
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if (peaks > 7)
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break;
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}
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}
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} else if (dir == FALL) {
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if (Y > last && last <= s->black) {
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dir = RISE;
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}
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}
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last = Y;
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}
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if (peaks != 7)
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return;
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for (i = 1; i < 7; i++)
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max_peak_diff = FFMAX(max_peak_diff, FFABS(clock[i][0] - clock[i-1][0]));
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if (max_peak_diff > s->max_peak_diff)
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return;
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max = 0; min = INT_MAX;
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for (i = 1; i < 7; i++) {
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max = FFMAX(max, FFABS(clock[i][1] - clock[i-1][1]));
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min = FFMIN(min, FFABS(clock[i][1] - clock[i-1][1]));
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}
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range = max - min;
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if (range > s->max_period_diff)
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return;
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s1 = src[sync_width + width_per_bit * 0 + width_per_bit / 2];
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s2 = src[sync_width + width_per_bit * 1 + width_per_bit / 2];
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s3 = src[sync_width + width_per_bit * 2 + width_per_bit / 2];
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if (FFABS(s1 - s2) > s->max_start_diff || s1 > s->black || s2 > s->black || s3 < s->white)
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return;
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for (ch = 0; ch < 2; ch++) {
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for (parity = 0, i = 0; i < 8; i++) {
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int b = src[sync_width + width_per_bit * (i + 3 + 8 * ch) + width_per_bit / 2];
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if (b - s1 > (s3 - s1) * s->bhd) {
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b = 1;
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parity++;
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} else {
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b = 0;
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}
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byte[ch] |= b << i;
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}
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if (s->chp) {
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if (!(parity & 1)) {
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byte[ch] = 0;
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}
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}
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}
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{
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uint8_t key[128], value[128];
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snprintf(key, sizeof(key), "lavfi.readeia608.%d.cc", s->nb_found);
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snprintf(value, sizeof(value), "0x%02X%02X", byte[0], byte[1]);
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av_dict_set(&in->metadata, key, value, 0);
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snprintf(key, sizeof(key), "lavfi.readeia608.%d.line", s->nb_found);
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snprintf(value, sizeof(value), "%d", line);
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av_dict_set(&in->metadata, key, value, 0);
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}
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s->nb_found++;
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}
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static int filter_frame(AVFilterLink *inlink, AVFrame *in)
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{
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AVFilterContext *ctx = inlink->dst;
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AVFilterLink *outlink = ctx->outputs[0];
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ReadEIA608Context *s = ctx->priv;
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int i;
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s->nb_found = 0;
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for (i = s->start; i <= s->end; i++)
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extract_line(ctx, inlink, in, i);
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return ff_filter_frame(outlink, in);
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}
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static const AVFilterPad readeia608_inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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.filter_frame = filter_frame,
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.config_props = config_input,
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},
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{ NULL }
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};
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static const AVFilterPad readeia608_outputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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},
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{ NULL }
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};
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AVFilter ff_vf_readeia608 = {
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.name = "readeia608",
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.description = NULL_IF_CONFIG_SMALL("Read EIA-608 Closed Caption codes from input video and write them to frame metadata."),
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.priv_size = sizeof(ReadEIA608Context),
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.priv_class = &readeia608_class,
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.query_formats = query_formats,
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.inputs = readeia608_inputs,
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.outputs = readeia608_outputs,
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.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
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};
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