/*
* Copyright (c) 2017 Paul B Mahol
*
* 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 closed captioning data (EIA-608).
* See also https://en.wikipedia.org/wiki/EIA-608
*/
#include <string.h>
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "libavutil/timestamp.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"
#define FALL 0
#define RISE 1
typedef struct ReadEIA608Context {
const AVClass *class;
int start, end;
int min_range;
int max_peak_diff;
int max_period_diff;
int max_start_diff;
int nb_found;
int white;
int black;
float mpd, mhd, msd, mac, spw, bhd, wth, bth;
int chp;
} ReadEIA608Context;
#define OFFSET(x) offsetof(ReadEIA608Context, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption readeia608_options[] = {
{ "scan_min", "set from which line to scan for codes", OFFSET(start), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
{ "scan_max", "set to which line to scan for codes", OFFSET(end), AV_OPT_TYPE_INT, {.i64=29}, 0, INT_MAX, FLAGS },
{ "mac", "set minimal acceptable amplitude change for sync codes detection", OFFSET(mac), AV_OPT_TYPE_FLOAT, {.dbl=.2}, 0.001, 1, FLAGS },
{ "spw", "set ratio of width reserved for sync code detection", OFFSET(spw), AV_OPT_TYPE_FLOAT, {.dbl=.27}, 0.1, 0.7, FLAGS },
{ "mhd", "set max peaks height difference for sync code detection", OFFSET(mhd), AV_OPT_TYPE_FLOAT, {.dbl=.1}, 0, 0.5, FLAGS },
{ "mpd", "set max peaks period difference for sync code detection", OFFSET(mpd), AV_OPT_TYPE_FLOAT, {.dbl=.1}, 0, 0.5, FLAGS },
{ "msd", "set first two max start code bits differences", OFFSET(msd), AV_OPT_TYPE_FLOAT, {.dbl=.02}, 0, 0.5, FLAGS },
{ "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 },
{ "th_w", "set white color threshold", OFFSET(wth), AV_OPT_TYPE_FLOAT, {.dbl=.35}, 0.1, 1, FLAGS },
{ "th_b", "set black color threshold", OFFSET(bth), AV_OPT_TYPE_FLOAT, {.dbl=.15}, 0, 0.5, FLAGS },
{ "chp", "check and apply parity bit", OFFSET(chp), AV_OPT_TYPE_BOOL, {.i64= 0}, 0, 1, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(readeia608);
static int query_formats(AVFilterContext *ctx)
{
static const enum AVPixelFormat pixel_fmts[] = {
AV_PIX_FMT_GRAY8,
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_YUVJ420P, AV_PIX_FMT_YUVJ422P,
AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
AV_PIX_FMT_YUVJ411P,
AV_PIX_FMT_NONE
};
AVFilterFormats *formats = ff_make_format_list(pixel_fmts);
if (!formats)
return AVERROR(ENOMEM);
return ff_set_common_formats(ctx, formats);
}
static int config_input(AVFilterLink *inlink)
{
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
AVFilterContext *ctx = inlink->dst;
ReadEIA608Context *s = ctx->priv;
int depth = desc->comp[0].depth;
if (s->end >= inlink->h) {
av_log(ctx, AV_LOG_WARNING, "Last line to scan too large, clipping.\n");
s->end = inlink->h - 1;
}
if (s->start > s->end) {
av_log(ctx, AV_LOG_ERROR, "Invalid range.\n");
return AVERROR(EINVAL);
}
s->min_range = s->mac * ((1 << depth) - 1);
s->max_peak_diff = s->mhd * ((1 << depth) - 1);
s->max_period_diff = s->mpd * ((1 << depth) - 1);
s->max_start_diff = s->msd * ((1 << depth) - 1);
s->white = s->wth * ((1 << depth) - 1);
s->black = s->bth * ((1 << depth) - 1);
return 0;
}
static void extract_line(AVFilterContext *ctx, AVFilterLink *inlink, AVFrame *in, int line)
{
ReadEIA608Context *s = ctx->priv;
int max = 0, min = INT_MAX;
int i, ch, range = 0;
const uint8_t *src;
uint16_t clock[8][2] = { { 0 } };
const int sync_width = s->spw * in->width;
int last = 0, peaks = 0, max_peak_diff = 0, dir = RISE;
const int width_per_bit = (in->width - sync_width) / 19;
uint8_t byte[2] = { 0 };
int s1, s2, s3, parity;
src = &in->data[0][line * in->linesize[0]];
for (i = 0; i < sync_width; i++) {
max = FFMAX(max, src[i]);
min = FFMIN(min, src[i]);
}
range = max - min;
if (range < s->min_range)
return;
for (i = 0; i < sync_width; i++) {
int Y = src[i];
if (dir == RISE) {
if (Y < last) {
dir = FALL;
if (last >= s->white) {
clock[peaks][0] = last;
clock[peaks][1] = i;
peaks++;
if (peaks > 7)
break;
}
}
} else if (dir == FALL) {
if (Y > last && last <= s->black) {
dir = RISE;
}
}
last = Y;
}
if (peaks != 7)
return;
for (i = 1; i < 7; i++)
max_peak_diff = FFMAX(max_peak_diff, FFABS(clock[i][0] - clock[i-1][0]));
if (max_peak_diff > s->max_peak_diff)
return;
max = 0; min = INT_MAX;
for (i = 1; i < 7; i++) {
max = FFMAX(max, FFABS(clock[i][1] - clock[i-1][1]));
min = FFMIN(min, FFABS(clock[i][1] - clock[i-1][1]));
}
range = max - min;
if (range > s->max_period_diff)
return;
s1 = src[sync_width + width_per_bit * 0 + width_per_bit / 2];
s2 = src[sync_width + width_per_bit * 1 + width_per_bit / 2];
s3 = src[sync_width + width_per_bit * 2 + width_per_bit / 2];
if (FFABS(s1 - s2) > s->max_start_diff || s1 > s->black || s2 > s->black || s3 < s->white)
return;
for (ch = 0; ch < 2; ch++) {
for (parity = 0, i = 0; i < 8; i++) {
int b = src[sync_width + width_per_bit * (i + 3 + 8 * ch) + width_per_bit / 2];
if (b - s1 > (s3 - s1) * s->bhd) {
b = 1;
parity++;
} else {
b = 0;
}
byte[ch] |= b << i;
}
if (s->chp) {
if (!(parity & 1)) {
byte[ch] = 0;
}
}
}
{
uint8_t key[128], value[128];
snprintf(key, sizeof(key), "lavfi.readeia608.%d.cc", s->nb_found);
snprintf(value, sizeof(value), "0x%02X%02X", byte[0], byte[1]);
av_dict_set(&in->metadata, key, value, 0);
snprintf(key, sizeof(key), "lavfi.readeia608.%d.line", s->nb_found);
snprintf(value, sizeof(value), "%d", line);
av_dict_set(&in->metadata, key, value, 0);
}
s->nb_found++;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
ReadEIA608Context *s = ctx->priv;
int i;
s->nb_found = 0;
for (i = s->start; i <= s->end; i++)
extract_line(ctx, inlink, in, i);
return ff_filter_frame(outlink, in);
}
static const AVFilterPad readeia608_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
.config_props = config_input,
},
{ NULL }
};
static const AVFilterPad readeia608_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
},
{ NULL }
};
AVFilter ff_vf_readeia608 = {
.name = "readeia608",
.description = NULL_IF_CONFIG_SMALL("Read EIA-608 Closed Caption codes from input video and write them to frame metadata."),
.priv_size = sizeof(ReadEIA608Context),
.priv_class = &readeia608_class,
.query_formats = query_formats,
.inputs = readeia608_inputs,
.outputs = readeia608_outputs,
.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
};