diff --git a/Changelog b/Changelog
index 29754be4c9..cd78d25a2e 100644
--- a/Changelog
+++ b/Changelog
@@ -8,6 +8,7 @@ version 5.1:
 - DFPWM audio encoder/decoder and raw muxer/demuxer
 - SITI filter
 - Vizrt Binary Image encoder/decoder
+- avsynctest source filter
 
 
 version 5.0:
diff --git a/doc/filters.texi b/doc/filters.texi
index 4e9b0e0111..24c2243b2a 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -29282,6 +29282,43 @@ Below is a description of the currently available multimedia sources.
 This is the same as @ref{movie} source, except it selects an audio
 stream by default.
 
+@section avsynctest
+Generate an Audio/Video Sync Test.
+
+Generated stream periodically shows flash video frame and emits beep in audio.
+Useful to inspect A/V sync issues.
+
+It accepts the following options:
+
+@table @option
+@item size, s
+Set output video size. Default value is @code{hd720}.
+
+@item framerate, fr
+Set output video frame rate. Default value is @code{30}.
+
+@item samplerate, sr
+Set output audio sample rate. Default value is @code{44100}.
+
+@item amplitude, a
+Set output audio beep amplitude. Default value is @code{0.7}.
+
+@item period, p
+Set output audio beep period in seconds. Default value is @code{3}.
+
+@item delay, dl
+Set output video flash delay in number of frames. Default value is @code{0}.
+
+@item cycle, c
+Enable cycling of video delays, by default is disabled.
+
+@item duration, d
+Set stream output duration. By default duration is unlimited.
+
+@item fg, bg, ag
+Set foreground/background/additional color.
+@end table
+
 @anchor{movie}
 @section movie
 
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index c4c946a988..2c2a5b8d83 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -579,6 +579,7 @@ OBJS-$(CONFIG_SHOWWAVESPIC_FILTER)           += avf_showwaves.o
 OBJS-$(CONFIG_SPECTRUMSYNTH_FILTER)          += vaf_spectrumsynth.o
 
 # multimedia sources
+OBJS-$(CONFIG_AVSYNCTEST_FILTER)             += src_avsynctest.o
 OBJS-$(CONFIG_AMOVIE_FILTER)                 += src_movie.o
 OBJS-$(CONFIG_MOVIE_FILTER)                  += src_movie.o
 
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 9fbaaacf47..aecad5a2b0 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -550,6 +550,7 @@ extern const AVFilter ff_avf_showwavespic;
 extern const AVFilter ff_vaf_spectrumsynth;
 
 /* multimedia sources */
+extern const AVFilter ff_avsrc_avsynctest;
 extern const AVFilter ff_avsrc_amovie;
 extern const AVFilter ff_avsrc_movie;
 
diff --git a/libavfilter/src_avsynctest.c b/libavfilter/src_avsynctest.c
new file mode 100644
index 0000000000..c78e517ac3
--- /dev/null
+++ b/libavfilter/src_avsynctest.c
@@ -0,0 +1,402 @@
+/*
+ * Copyright (c) 2017-2022 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
+ */
+
+#include "libavutil/avassert.h"
+#include "libavutil/common.h"
+#include "libavutil/channel_layout.h"
+#include "libavutil/ffmath.h"
+#include "libavutil/opt.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/parseutils.h"
+#include "libavutil/timestamp.h"
+#include "libavutil/xga_font_data.h"
+#include "avfilter.h"
+#include "drawutils.h"
+#include "filters.h"
+#include "formats.h"
+#include "internal.h"
+#include "audio.h"
+#include "video.h"
+
+typedef struct AVSyncTestContext {
+    const AVClass *class;
+
+    int w, h;
+    AVRational frame_rate;
+    int sample_rate;
+    int64_t duration;
+    int64_t apts, vpts;
+    float amplitude;
+    int period;
+    int delay;
+    int cycle;
+
+    int beep;
+    int beep_duration;
+    int flash;
+    int dir;
+    AVRational vdelay, delay_max, delay_min;
+    AVRational delay_range;
+    int64_t prev_intpart;
+
+    uint8_t rgba[3][4];
+    FFDrawContext draw;
+    FFDrawColor fg;
+    FFDrawColor bg;
+    FFDrawColor ag;
+} AVSyncTestContext;
+
+#define OFFSET(x) offsetof(AVSyncTestContext, x)
+#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+#define V AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption avsynctest_options[] = {
+    {"size",       "set frame size",  OFFSET(w),            AV_OPT_TYPE_IMAGE_SIZE, {.str="hd720"},   0,   0, V },
+    {"s",          "set frame size",  OFFSET(w),            AV_OPT_TYPE_IMAGE_SIZE, {.str="hd720"},   0,   0, V },
+    {"framerate",  "set frame rate",  OFFSET(frame_rate),   AV_OPT_TYPE_VIDEO_RATE, {.str="30"},   0,INT_MAX, V },
+    {"fr",         "set frame rate",  OFFSET(frame_rate),   AV_OPT_TYPE_VIDEO_RATE, {.str="30"},   0,INT_MAX, V },
+    {"samplerate", "set sample rate", OFFSET(sample_rate),  AV_OPT_TYPE_INT,        {.i64=44100},8000,384000, A },
+    {"sr",         "set sample rate", OFFSET(sample_rate),  AV_OPT_TYPE_INT,        {.i64=44100},8000,384000, A },
+    {"amplitude",  "set beep amplitude", OFFSET(amplitude), AV_OPT_TYPE_FLOAT,      {.dbl=.7},       0.,  1., A },
+    {"a",          "set beep amplitude", OFFSET(amplitude), AV_OPT_TYPE_FLOAT,      {.dbl=.7},       0.,  1., A },
+    {"period",     "set beep period", OFFSET(period),       AV_OPT_TYPE_INT,        {.i64=3},         1, 99., A },
+    {"p",          "set beep period", OFFSET(period),       AV_OPT_TYPE_INT,        {.i64=3},         1, 99., A },
+    {"delay",      "set flash delay", OFFSET(delay),        AV_OPT_TYPE_INT,        {.i64=0},       -30,  30, V },
+    {"dl",         "set flash delay", OFFSET(delay),        AV_OPT_TYPE_INT,        {.i64=0},       -30,  30, V },
+    {"cycle",      "set delay cycle", OFFSET(cycle),        AV_OPT_TYPE_BOOL,       {.i64=0},         0,   1, V },
+    {"c",          "set delay cycle", OFFSET(cycle),        AV_OPT_TYPE_BOOL,       {.i64=0},         0,   1, V },
+    {"duration",   "set duration",    OFFSET(duration),     AV_OPT_TYPE_DURATION,   {.i64=0},         0, INT64_MAX, V|A },
+    {"d",          "set duration",    OFFSET(duration),     AV_OPT_TYPE_DURATION,   {.i64=0},         0, INT64_MAX, V|A },
+    {"fg",         "set foreground color", OFFSET(rgba[0]), AV_OPT_TYPE_COLOR,      {.str="white"},   0,   0, V },
+    {"bg",         "set background color", OFFSET(rgba[1]), AV_OPT_TYPE_COLOR,      {.str="black"},   0,   0, V },
+    {"ag",         "set additional color", OFFSET(rgba[2]), AV_OPT_TYPE_COLOR,      {.str="gray"},    0,   0, V },
+    {NULL},
+};
+
+AVFILTER_DEFINE_CLASS(avsynctest);
+
+static av_cold int query_formats(AVFilterContext *ctx)
+{
+    AVSyncTestContext *s = ctx->priv;
+    AVFilterChannelLayouts *chlayout = NULL;
+    int sample_rates[] = { s->sample_rate, -1 };
+    static const enum AVSampleFormat sample_fmts[] = {
+        AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_NONE
+    };
+    AVFilterFormats *formats;
+    int ret;
+
+    formats = ff_make_format_list(sample_fmts);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    if ((ret = ff_formats_ref(formats, &ctx->outputs[0]->incfg.formats)) < 0)
+        return ret;
+
+    formats = ff_draw_supported_pixel_formats(0);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    if ((ret = ff_formats_ref(formats, &ctx->outputs[1]->incfg.formats)) < 0)
+        return ret;
+
+    if ((ret = ff_add_channel_layout(&chlayout, &(AVChannelLayout)AV_CHANNEL_LAYOUT_MONO)) < 0)
+        return ret;
+    ret = ff_set_common_channel_layouts(ctx, chlayout);
+    if (ret < 0)
+        return ret;
+
+    formats = ff_make_format_list(sample_rates);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    return ff_set_common_samplerates(ctx, formats);
+}
+
+static av_cold int aconfig_props(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVSyncTestContext *s = ctx->priv;
+
+    outlink->sample_rate = s->sample_rate;
+    outlink->time_base = (AVRational){1, s->sample_rate};
+
+    s->beep_duration = av_rescale(s->sample_rate, s->frame_rate.den, s->frame_rate.num);
+    s->duration = av_rescale(s->duration, s->sample_rate, AV_TIME_BASE);
+
+    return 0;
+}
+
+static av_cold int config_props(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVSyncTestContext *s = ctx->priv;
+
+    outlink->w = s->w;
+    outlink->h = s->h;
+    outlink->time_base = av_inv_q(s->frame_rate);
+    outlink->frame_rate = s->frame_rate;
+    outlink->sample_aspect_ratio = (AVRational) {1, 1};
+    s->delay_min = av_mul_q(s->frame_rate, av_make_q(-1, 2));
+    s->delay_max = av_mul_q(s->delay_min, av_make_q(-1, 1));
+    s->delay_range = av_sub_q(s->delay_max, s->delay_min);
+    s->vdelay = av_make_q(s->delay, 1);
+    s->dir = 1;
+    s->prev_intpart = INT64_MIN;
+
+    ff_draw_init(&s->draw, outlink->format, 0);
+
+    ff_draw_color(&s->draw, &s->fg, s->rgba[0]);
+    ff_draw_color(&s->draw, &s->bg, s->rgba[1]);
+    ff_draw_color(&s->draw, &s->ag, s->rgba[2] );
+
+    return 0;
+}
+
+#define FPI 0x8000
+
+static int32_t sin32(int32_t x, int shift)
+{
+    const double pi = M_PI;
+    const int32_t a = ((2.0 * pi) * (1 << 24));
+    const int32_t b = (1 << 7) * (12.0 / pi - 1.0 - pi) * (1 << 24);
+    const int32_t c = (1 << 9) * 3.0 * (2.0 + pi - 16.0 / pi) * (1 << 24);
+    int64_t x2, result;
+    int32_t t1, t2;
+
+    x &= 2 * FPI - 1;
+
+    if (x >= (3 * FPI / 2))
+        x = x - 2 * FPI;
+    else if (x > FPI / 2)
+        x = FPI - x;
+
+    x2 = x * x;
+    t1 = (x2 * c) >> 32;
+    t2 = ((b + t1) * x2) >> 32;
+    x = x << 8;
+
+    result = a + t2;
+    result *= x;
+    result += (1U << 31);
+    result >>= (32 - shift);
+
+    return result;
+}
+
+static int audio_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVSyncTestContext *s = ctx->priv;
+    const int a = lrintf(s->amplitude * 15);
+    int64_t duration[2];
+    int64_t delta;
+    AVFrame *out;
+    int32_t *dst;
+
+    delta = av_rescale_q(s->vpts, av_make_q(s->sample_rate, 1), s->frame_rate) - s->apts;
+    if (delta < 0)
+        return 1;
+
+    duration[0] = av_rescale_rnd(s->sample_rate, s->frame_rate.den, s->frame_rate.num, AV_ROUND_DOWN);
+    duration[1] = av_rescale_rnd(s->sample_rate, s->frame_rate.den, s->frame_rate.num, AV_ROUND_UP);
+
+    delta = duration[delta > 0];
+    out = ff_get_audio_buffer(outlink, delta);
+    if (!out)
+        return AVERROR(ENOMEM);
+
+    out->pts = s->apts;
+    dst = (int32_t *)out->data[0];
+
+    for (int i = 0; i < delta; i++) {
+        if (((s->apts + i) % (s->period * s->sample_rate)) == 0)
+            s->beep = 1;
+        if (s->beep) {
+            dst[i] = sin32(av_rescale_q(800LL * 2LL * FPI, outlink->time_base, av_make_q(1, s->apts + i)), a);
+            s->beep++;
+        } else {
+            dst[i] = 0;
+        }
+        if (s->beep >= s->beep_duration) {
+            s->beep = 0;
+        }
+    }
+    s->apts += out->nb_samples;
+
+    return ff_filter_frame(outlink, out);
+}
+
+static void draw_text(FFDrawContext *draw, AVFrame *out, FFDrawColor *color,
+                      int x0, int y0, const uint8_t *text)
+{
+    int x = x0;
+
+    for (; *text; text++) {
+        if (*text == '\n') {
+            x = x0;
+            y0 += 8;
+            continue;
+        }
+        ff_blend_mask(draw, color, out->data, out->linesize,
+                      out->width, out->height,
+                      avpriv_cga_font + *text * 8, 1, 8, 8, 0, 0, x, y0);
+        x += 8;
+    }
+}
+
+static int offset(int x, int num, int den)
+{
+    return av_rescale_rnd(x, num, den, AV_ROUND_UP);
+}
+
+static int video_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVSyncTestContext *s = ctx->priv;
+    const int w = outlink->w;
+    const int h = outlink->h;
+    const int step = av_rescale_rnd(w, s->delay_range.den, s->delay_range.num, AV_ROUND_DOWN);
+    char text[128];
+    int new_offset;
+    int64_t delta, temp, intpart;
+    AVFrame *out;
+
+    delta = av_rescale_q(s->apts, s->frame_rate, av_make_q(s->sample_rate, 1)) - s->vpts;
+    if (delta < 0)
+        return 1;
+
+    out = ff_get_video_buffer(outlink, w, h);
+    if (!out)
+        return AVERROR(ENOMEM);
+
+    ff_fill_rectangle(&s->draw, &s->bg, out->data, out->linesize, 0, 0, w, h);
+
+    snprintf(text, sizeof(text), "FRN: %"PRId64"", s->vpts);
+    draw_text(&s->draw, out, &s->fg, offset(w, 1, 10), offset(h, 1, 10), text);
+
+    snprintf(text, sizeof(text), "SEC: %s", av_ts2timestr(s->vpts, &outlink->time_base));
+    draw_text(&s->draw, out, &s->fg, offset(w, 1, 10), offset(h, 9, 10), text);
+
+    snprintf(text, sizeof(text), "DLY: %d", s->vdelay.num);
+    draw_text(&s->draw, out, &s->fg, offset(w, 9, 10) - strlen(text) * 8, offset(h, 9, 10), text);
+
+    snprintf(text, sizeof(text), "FPS: %d/%d", s->frame_rate.num, s->frame_rate.den);
+    draw_text(&s->draw, out, &s->fg, offset(w, 9, 10) - strlen(text) * 8, offset(h, 1, 10), text);
+
+    snprintf(text, sizeof(text), "P: %d", s->period);
+    draw_text(&s->draw, out, &s->ag, offset(w, 1, 2) - strlen(text) * 4, offset(h, 9, 10), text);
+
+    snprintf(text, sizeof(text), "SR: %d", s->sample_rate);
+    draw_text(&s->draw, out, &s->ag, offset(w, 1, 2) - strlen(text) * 4, offset(h, 1, 10), text);
+
+    snprintf(text, sizeof(text), "A: %1.2f", s->amplitude);
+    draw_text(&s->draw, out, &s->ag, offset(w, 1, 10), offset(h, 1, 2), text);
+
+    snprintf(text, sizeof(text), "WxH: %dx%d", w, h);
+    draw_text(&s->draw, out, &s->ag, offset(w, 9, 10) - strlen(text) * 8, offset(h, 1, 2), text);
+
+    temp    = s->vpts + s->vdelay.num;
+    intpart = av_rescale_rnd(temp, outlink->time_base.num, outlink->time_base.den, AV_ROUND_NEAR_INF);
+    intpart = temp - av_rescale_rnd(intpart, outlink->time_base.den, outlink->time_base.num, AV_ROUND_NEAR_INF);
+
+    new_offset = offset(w, 1, 2);
+    ff_fill_rectangle(&s->draw, &s->fg, out->data, out->linesize,
+                      av_clip(new_offset + step * intpart, 0, w - 2),
+                      offset(h, 141, 200), offset(step, 2, 3), offset(h, 1, 25));
+
+    if (intpart == 0 && s->prev_intpart != intpart) {
+        if (s->flash >= s->period) {
+            int result;
+
+            if (s->cycle)
+                s->vdelay = av_add_q(s->vdelay, av_make_q(s->dir, 1));
+            result = av_cmp_q(s->vdelay, s->delay_max);
+            if (result >= 0)
+                s->dir = -1;
+            result = av_cmp_q(s->vdelay, s->delay_min);
+            if (result <= 0)
+                s->dir = 1;
+            ff_fill_rectangle(&s->draw, &s->fg, out->data, out->linesize,
+                              offset(w, 1, 3), offset(h, 1, 3), offset(w, 1, 3), offset(h, 1, 4));
+            s->flash = 0;
+        }
+        s->flash++;
+    }
+    s->prev_intpart = intpart;
+
+    for (int i = av_rescale(s->delay_min.num, 1, s->delay_min.den);
+             i < av_rescale(s->delay_max.num, 1, s->delay_max.den); i++) {
+        ff_fill_rectangle(&s->draw, &s->fg, out->data, out->linesize,
+                          av_clip(new_offset + step * i, 0, w - 2),
+                          offset(h, 7, 10), 1, offset(h, 1, 20));
+    }
+
+    out->pts = s->vpts++;
+
+    return ff_filter_frame(outlink, out);
+}
+
+static int activate(AVFilterContext *ctx)
+{
+    AVSyncTestContext *s = ctx->priv;
+    AVFilterLink *aoutlink = ctx->outputs[0];
+    AVFilterLink *voutlink = ctx->outputs[1];
+    int ret = FFERROR_NOT_READY;
+
+    if (!ff_outlink_frame_wanted(aoutlink) &&
+        !ff_outlink_frame_wanted(voutlink))
+        return ret;
+
+    if (s->duration > 0 && s->apts >= s->duration) {
+        ff_outlink_set_status(aoutlink, AVERROR_EOF, s->apts);
+        ff_outlink_set_status(voutlink, AVERROR_EOF, s->vpts);
+        return 0;
+    }
+
+    ret = audio_frame(aoutlink);
+    if (ret < 0)
+        return ret;
+    ret = video_frame(voutlink);
+
+    return ret;
+}
+
+static const AVFilterPad avsynctest_outputs[] = {
+    {
+        .name          = "audio",
+        .type          = AVMEDIA_TYPE_AUDIO,
+        .config_props  = aconfig_props,
+    },
+    {
+        .name          = "video",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = config_props,
+    },
+};
+
+const AVFilter ff_avsrc_avsynctest = {
+    .name          = "avsynctest",
+    .description   = NULL_IF_CONFIG_SMALL("Generate an Audio Video Sync Test."),
+    .priv_size     = sizeof(AVSyncTestContext),
+    .priv_class    = &avsynctest_class,
+    .inputs        = NULL,
+    .activate      = activate,
+    FILTER_OUTPUTS(avsynctest_outputs),
+    FILTER_QUERY_FUNC(query_formats),
+};
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 32d713eff8..66a6aaf602 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -31,7 +31,7 @@
 
 #include "version_major.h"
 
-#define LIBAVFILTER_VERSION_MINOR  30
+#define LIBAVFILTER_VERSION_MINOR  31
 #define LIBAVFILTER_VERSION_MICRO 100