avfilter: add EIA-608 line extractor

Signed-off-by: Dave Rice <dave@dericed.com>
Signed-off-by: Paul B Mahol <onemda@gmail.com>

Changelog

@@ -15,6 +15,7 @@ version <next>:
 - QDMC audio decoder
 - NewTek SpeedHQ decoder
 - MIDI Sample Dump Standard demuxer
+- readeia608 filter
 
 version 3.2:
 - libopenmpt demuxer

doc/filters.texi

@@ -11253,6 +11253,76 @@ less than @code{0}, the filter will try to use a good random seed on a
 best effort basis.
 @end table
 
+@section readeia608
+
+Read closed captioning (EIA-608) information from the top lines of a video frame.
+
+This filter adds frame metadata for @code{lavfi.readeia608.X.cc} and
+@code{lavfi.readeia608.X.line}, where @code{X} is the number of the identified line
+with EIA-608 data (starting from 0). A description of each metadata value follows:
+
+@table @option
+@item lavfi.readeia608.X.cc
+The two bytes stored as EIA-608 data (printed in hexadecimal).
+
+@item lavfi.readeia608.X.line
+The number of the line on which the EIA-608 data was identified and read.
+@end table
+
+This filter accepts the following options:
+
+@table @option
+@item scan_min
+Set the line to start scanning for EIA-608 data. Default is @code{0}.
+
+@item scan_max
+Set the line to end scanning for EIA-608 data. Default is @code{29}.
+
+@item mac
+Set minimal acceptable amplitude change for sync codes detection.
+Default is @code{0.2}. Allowed range is @code{[0.001 - 1]}.
+
+@item spw
+Set the ratio of width reserved for sync code detection.
+Default is @code{0.27}. Allowed range is @code{[0.01 - 0.7]}.
+
+@item mhd
+Set the max peaks height difference for sync code detection.
+Default is @code{0.1}. Allowed range is @code{[0.0 - 0.5]}.
+
+@item mpd
+Set max peaks period difference for sync code detection.
+Default is @code{0.1}. Allowed range is @code{[0.0 - 0.5]}.
+
+@item msd
+Set the first two max start code bits differences.
+Default is @code{0.02}. Allowed range is @code{[0.0 - 0.5]}.
+
+@item bhd
+Set the minimum ratio of bits height compared to 3rd start code bit.
+Default is @code{0.75}. Allowed range is @code{[0.01 - 1]}.
+
+@item th_w
+Set the white color threshold. Default is @code{0.35}. Allowed range is @code{[0.1 - 1]}.
+
+@item th_b
+Set the black color threshold. Default is @code{0.15}. Allowed range is @code{[0.0 - 0.5]}.
+
+@item chp
+Enable checking the parity bit. In the event of a parity error, the filter will output
+@code{0x00} for that character. Default is false.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Output a csv with presentation time and the first two lines of identified EIA-608 captioning data.
+@example
+ffprobe -f lavfi -i movie=captioned_video.mov,readeia608 -show_entries frame=pkt_pts_time:frame_tags=lavfi.readeia608.0.cc,lavfi.readeia608.1.cc -of csv
+@end example
+@end itemize
+
 @section readvitc
 
 Read vertical interval timecode (VITC) information from the top lines of a

libavfilter/Makefile

@@ -247,6 +247,7 @@ OBJS-$(CONFIG_PSNR_FILTER)                   += vf_psnr.o dualinput.o framesync.
 OBJS-$(CONFIG_PULLUP_FILTER)                 += vf_pullup.o
 OBJS-$(CONFIG_QP_FILTER)                     += vf_qp.o
 OBJS-$(CONFIG_RANDOM_FILTER)                 += vf_random.o
+OBJS-$(CONFIG_READEIA608_FILTER)             += vf_readeia608.o
 OBJS-$(CONFIG_READVITC_FILTER)               += vf_readvitc.o
 OBJS-$(CONFIG_REALTIME_FILTER)               += f_realtime.o
 OBJS-$(CONFIG_REMAP_FILTER)                  += vf_remap.o framesync.o

libavfilter/allfilters.c

@@ -262,6 +262,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(PULLUP,         pullup,         vf);
     REGISTER_FILTER(QP,             qp,             vf);
     REGISTER_FILTER(RANDOM,         random,         vf);
+    REGISTER_FILTER(READEIA608,     readeia608,     vf);
     REGISTER_FILTER(READVITC,       readvitc,       vf);
     REGISTER_FILTER(REALTIME,       realtime,       vf);
     REGISTER_FILTER(REMAP,          remap,          vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  69
+#define LIBAVFILTER_VERSION_MINOR  70
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vf_readeia608.c

+/*
+ * 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(avpriv_frame_get_metadatap(in), key, value, 0);
+
+        snprintf(key, sizeof(key), "lavfi.readeia608.%d.line", s->nb_found);
+        snprintf(value, sizeof(value), "%d", line);
+        av_dict_set(avpriv_frame_get_metadatap(in), 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,
+};