[FFmpeg-devel,v2] avfilter: add QSV variants of the stack filters

diff --git a/configure b/configure
index 94b30afe74..d29ae36006 100755
--- a/configure
+++ b/configure
@@ -3700,6 +3700,12 @@  vpp_qsv_filter_select="qsvvpp"
 xfade_opencl_filter_deps="opencl"
 yadif_cuda_filter_deps="ffnvcodec"
 yadif_cuda_filter_deps_any="cuda_nvcc cuda_llvm"
+hstack_qsv_filter_deps="libmfx"
+hstack_qsv_filter_select="qsvvpp"
+vstack_qsv_filter_deps="libmfx"
+vstack_qsv_filter_select="qsvvpp"
+xstack_qsv_filter_deps="libmfx"
+xstack_qsv_filter_select="qsvvpp"
 
 # examples
 avio_list_dir_deps="avformat avutil"
diff --git a/doc/filters.texi b/doc/filters.texi
index 66c0f87e47..0fdefabe96 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -23998,6 +23998,84 @@  tonemap_vaapi=format=p010:t=bt2020-10
 
 @c man end VAAPI VIDEO FILTERS
 
+@chapter QSV Video Filters
+@c man begin QSV VIDEO FILTERS
+
+Below is a description of the currently available QSV video filters.
+
+To enable compilation of these filters you need to configure FFmpeg with
+@code{--enable-libmfx}.
+
+To use QSV filters, you need to setup the QSV device correctly. For more information, please read @url{https://trac.ffmpeg.org/wiki/Hardware/QuickSync}
+
+@section hstack_qsv
+Stack input videos horizontally.
+
+This is the QSV variant of the @ref{hstack} filter.
+
+It accepts the following options:
+
+@table @option
+@item inputs
+Set number of input streams. Allowed range is from 2 to 72.
+Default value is 2.
+
+@item shortest
+See @ref{hstack}.
+
+@item scale
+Set factor to zoom in or out all videos. Allowed range is from 0.125 to 8.
+Default value is 1.
+@end table
+
+@section vstack_qsv
+Stack input videos vertically.
+
+This is the QSV variant of the @ref{vstack} filter.
+
+It accepts the following options:
+
+@table @option
+@item inputs
+Set number of input streams. Allowed range is from 2 to 72.
+Default value is 2.
+
+@item shortest
+See @ref{vstack}.
+
+@item scale
+Set factor to zoom in or out all videos. Allowed range is from 0.125 to 8.
+Default value is 1.
+@end table
+
+@section xstack_qsv
+Stack video inputs into custom layout.
+
+This is the QSV variant of the @ref{xstack_qsv} filter.
+
+It accepts the following options:
+
+@table @option
+@item inputs
+Set number of input streams. Allowed range is from 2 to 72.
+Default value is 2.
+
+@item shortest
+See @ref{xstack}.
+
+@item scale
+Set factor to zoom in or out all videos. Allowed range is from 0.125 to 8.
+Default value is 1.
+
+@item layout
+See @ref{xstack}.
+
+@item fill
+See @ref{xstack}.
+@end table
+
+@c man end QSV VIDEO FILTERS
+
 @chapter Video Sources
 @c man begin VIDEO SOURCES
 
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 49c0c8342b..03e8558635 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -496,6 +496,9 @@  OBJS-$(CONFIG_YAEPBLUR_FILTER)               += vf_yaepblur.o
 OBJS-$(CONFIG_ZMQ_FILTER)                    += f_zmq.o
 OBJS-$(CONFIG_ZOOMPAN_FILTER)                += vf_zoompan.o
 OBJS-$(CONFIG_ZSCALE_FILTER)                 += vf_zscale.o
+OBJS-$(CONFIG_HSTACK_QSV_FILTER)             += vf_stack_qsv.o framesync.o
+OBJS-$(CONFIG_VSTACK_QSV_FILTER)             += vf_stack_qsv.o framesync.o
+OBJS-$(CONFIG_XSTACK_QSV_FILTER)             += vf_stack_qsv.o framesync.o
 
 OBJS-$(CONFIG_ALLRGB_FILTER)                 += vsrc_testsrc.o
 OBJS-$(CONFIG_ALLYUV_FILTER)                 += vsrc_testsrc.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index ae74f9c891..16bc0c6429 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -472,6 +472,9 @@  extern const AVFilter ff_vf_yaepblur;
 extern const AVFilter ff_vf_zmq;
 extern const AVFilter ff_vf_zoompan;
 extern const AVFilter ff_vf_zscale;
+extern const AVFilter ff_vf_hstack_qsv;
+extern const AVFilter ff_vf_vstack_qsv;
+extern const AVFilter ff_vf_xstack_qsv;
 
 extern const AVFilter ff_vsrc_allrgb;
 extern const AVFilter ff_vsrc_allyuv;
diff --git a/libavfilter/vf_stack_qsv.c b/libavfilter/vf_stack_qsv.c
new file mode 100644
index 0000000000..3d39e3ec60
--- /dev/null
+++ b/libavfilter/vf_stack_qsv.c
@@ -0,0 +1,498 @@ 
+/*
+ * 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
+ * Hardware accelerated hstack, vstack and xstack filters based on Intel Quick Sync Video VPP
+ */
+
+#include "libavutil/opt.h"
+#include "libavutil/common.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/eval.h"
+#include "libavutil/hwcontext.h"
+#include "libavutil/avstring.h"
+#include "libavutil/avassert.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/mathematics.h"
+#include "libavutil/parseutils.h"
+
+#include "internal.h"
+#include "filters.h"
+#include "formats.h"
+#include "video.h"
+
+#include "framesync.h"
+#include "qsvvpp.h"
+
+#define OFFSET(x) offsetof(QSVStackContext, x)
+#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
+
+enum {
+    QSV_STACK_H = 0,
+    QSV_STACK_V = 1,
+    QSV_STACK_X = 2
+};
+
+typedef struct QSVStackContext {
+    const AVClass *class;
+    QSVVPPContext *qsv;
+    QSVVPPParam qsv_param;
+    mfxExtVPPComposite comp_conf;
+    int mode;
+    FFFrameSync fs;
+
+    /* Options */
+    int nb_inputs;
+    int shortest;
+    double scale;
+    char *layout;
+    uint8_t fillcolor[4];
+    char *fillcolor_str;
+    int fillcolor_enable;
+} QSVStackContext;
+
+static void rgb2yuv(float r, float g, float b, int *y, int *u, int *v, int depth)
+{
+    *y = ((0.21260*219.0/255.0) * r + (0.71520*219.0/255.0) * g +
+         (0.07220*219.0/255.0) * b) * ((1 << depth) - 1);
+    *u = (-(0.11457*224.0/255.0) * r - (0.38543*224.0/255.0) * g +
+         (0.50000*224.0/255.0) * b + 0.5) * ((1 << depth) - 1);
+    *v = ((0.50000*224.0/255.0) * r - (0.45415*224.0/255.0) * g -
+         (0.04585*224.0/255.0) * b + 0.5) * ((1 << depth) - 1);
+}
+
+static int process_frame(FFFrameSync *fs)
+{
+    AVFilterContext *ctx = fs->parent;
+    QSVStackContext *sctx = fs->opaque;
+    AVFrame  *frame = NULL;
+    int ret = 0, i;
+
+    for (i = 0; i < ctx->nb_inputs; i++) {
+        ret = ff_framesync_get_frame(fs, i, &frame, 0);
+        if (ret == 0)
+            ret = ff_qsvvpp_filter_frame(sctx->qsv, ctx->inputs[i], frame);
+        if (ret < 0 && ret != AVERROR(EAGAIN))
+            break;
+    }
+
+    if (ret == 0 && sctx->qsv->got_frame == 0) {
+        for (i = 0; i < ctx->nb_inputs; i++)
+            FF_FILTER_FORWARD_WANTED(ctx->outputs[0], ctx->inputs[i]);
+
+        ret = FFERROR_NOT_READY;
+    }
+
+    return ret;
+}
+
+static int init_framesync(AVFilterContext *ctx)
+{
+    QSVStackContext *sctx = ctx->priv;
+    int ret, i;
+
+    ret = ff_framesync_init(&sctx->fs, ctx, ctx->nb_inputs);
+
+    if (ret < 0)
+        return ret;
+
+    sctx->fs.on_event = process_frame;
+    sctx->fs.opaque = sctx;
+
+    for (i = 0; i < ctx->nb_inputs; i++) {
+        FFFrameSyncIn *in = &sctx->fs.in[i];
+        in->before = EXT_STOP;
+        in->after = sctx->shortest ? EXT_STOP : EXT_INFINITY;
+        in->sync = i ? 1 : 2;
+        in->time_base = ctx->inputs[i]->time_base;
+    }
+
+    return ff_framesync_configure(&sctx->fs);
+}
+
+#define SET_INPUT_STREAM(is, x, y, w, h) do {   \
+        is->DstX = x;                           \
+        is->DstY = y;                           \
+        is->DstW = w;                           \
+        is->DstH = h;                           \
+        is->GlobalAlpha = 255;                  \
+        is->GlobalAlphaEnable = 1;              \
+        is->PixelAlphaEnable = 0;               \
+    } while (0)
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    QSVStackContext *sctx = ctx->priv;
+    AVFilterLink *inlink0 = ctx->inputs[0];
+    int width, height, i, ret;
+    enum AVPixelFormat in_format;
+    int depth = 8;
+
+    if (inlink0->format == AV_PIX_FMT_QSV) {
+         if (!inlink0->hw_frames_ctx || !inlink0->hw_frames_ctx->data)
+             return AVERROR(EINVAL);
+
+         in_format = ((AVHWFramesContext*)inlink0->hw_frames_ctx->data)->sw_format;
+    } else
+        in_format = inlink0->format;
+
+    sctx->qsv_param.out_sw_format = in_format;
+
+    for (i = 1; i < sctx->nb_inputs; i++) {
+        AVFilterLink *inlink = ctx->inputs[i];
+
+        if (inlink0->format == AV_PIX_FMT_QSV) {
+            AVHWFramesContext *hwfc0 = (AVHWFramesContext *)inlink0->hw_frames_ctx->data;
+            AVHWFramesContext *hwfc = (AVHWFramesContext *)inlink->hw_frames_ctx->data;
+
+            if (inlink0->format != inlink->format) {
+                av_log(ctx, AV_LOG_ERROR, "Mixing hardware and software pixel formats is not supported.\n");
+
+                return AVERROR(EINVAL);
+            } else if (hwfc0->device_ctx != hwfc->device_ctx) {
+                av_log(ctx, AV_LOG_ERROR, "Inputs with different underlying QSV devices are forbidden.\n");
+
+                return AVERROR(EINVAL);
+            }
+        }
+    }
+
+    if (in_format == AV_PIX_FMT_P010)
+        depth = 10;
+
+    if (sctx->fillcolor_enable) {
+        int Y, U, V;
+
+        rgb2yuv(sctx->fillcolor[0] / 255.0, sctx->fillcolor[1] / 255.0,
+                sctx->fillcolor[2] / 255.0, &Y, &U, &V, depth);
+        sctx->comp_conf.Y = Y;
+        sctx->comp_conf.U = U;
+        sctx->comp_conf.V = V;
+    }
+
+    if (sctx->mode == QSV_STACK_H) {
+        height = inlink0->h * sctx->scale;
+        width = 0;
+
+        for (i = 0; i < sctx->nb_inputs; i++) {
+            AVFilterLink *inlink = ctx->inputs[i];
+            mfxVPPCompInputStream *is = &sctx->comp_conf.InputStream[i];
+
+            if (inlink0->h != inlink->h) {
+                av_log(ctx, AV_LOG_ERROR, "Input %d height %d does not match input %d height %d.\n", i, inlink->h, 0, inlink0->h);
+                return AVERROR(EINVAL);
+            }
+
+            SET_INPUT_STREAM(is, width, 0, inlink->w * sctx->scale, inlink->h * sctx->scale);
+            width += inlink->w * sctx->scale;
+        }
+    } else if (sctx->mode == QSV_STACK_V) {
+        height = 0;
+        width = inlink0->w * sctx->scale;
+
+        for (i = 0; i < sctx->nb_inputs; i++) {
+            AVFilterLink *inlink = ctx->inputs[i];
+            mfxVPPCompInputStream *is = &sctx->comp_conf.InputStream[i];
+
+            if (inlink0->w != inlink->w) {
+                av_log(ctx, AV_LOG_ERROR, "Input %d width %d does not match input %d width %d.\n", i, inlink->w, 0, inlink0->w);
+                return AVERROR(EINVAL);
+            }
+
+            SET_INPUT_STREAM(is, 0, height, inlink->w * sctx->scale, inlink->h * sctx->scale);
+            height += inlink->h * sctx->scale;
+        }
+    } else {
+        char *arg, *p = sctx->layout, *saveptr = NULL;
+        char *arg2, *p2, *saveptr2 = NULL;
+        char *arg3, *p3, *saveptr3 = NULL;
+        int inw, inh, size, j;
+
+        width = ctx->inputs[0]->w * sctx->scale;
+        height = ctx->inputs[0]->h * sctx->scale;
+
+        for (i = 0; i < sctx->nb_inputs; i++) {
+            AVFilterLink *inlink = ctx->inputs[i];
+            mfxVPPCompInputStream *is = &sctx->comp_conf.InputStream[i];
+
+            if (!(arg = av_strtok(p, "|", &saveptr)))
+                return AVERROR(EINVAL);
+
+            p = NULL;
+            p2 = arg;
+            inw = inh = 0;
+
+            for (j = 0; j < 2; j++) {
+                if (!(arg2 = av_strtok(p2, "_", &saveptr2)))
+                    return AVERROR(EINVAL);
+
+                p2 = NULL;
+                p3 = arg2;
+
+                while ((arg3 = av_strtok(p3, "+", &saveptr3))) {
+                    p3 = NULL;
+                    if (sscanf(arg3, "w%d", &size) == 1) {
+                        if (size == i || size < 0 || size >= sctx->nb_inputs)
+                            return AVERROR(EINVAL);
+
+                        if (!j)
+                            inw += ctx->inputs[size]->w * sctx->scale;
+                        else
+                            inh += ctx->inputs[size]->w * sctx->scale;
+                    } else if (sscanf(arg3, "h%d", &size) == 1) {
+                        if (size == i || size < 0 || size >= sctx->nb_inputs)
+                            return AVERROR(EINVAL);
+
+                        if (!j)
+                            inw += ctx->inputs[size]->h * sctx->scale;
+                        else
+                            inh += ctx->inputs[size]->h * sctx->scale;
+                    } else if (sscanf(arg3, "%d", &size) == 1) {
+                        if (size < 0)
+                            return AVERROR(EINVAL);
+
+                        if (!j)
+                            inw += size;
+                        else
+                            inh += size;
+                    } else {
+                        return AVERROR(EINVAL);
+                    }
+                }
+            }
+
+            SET_INPUT_STREAM(is, inw, inh, inlink->w * sctx->scale, inlink->h * sctx->scale);
+            width = FFMAX(width, inlink->w * sctx->scale + inw);
+            height = FFMAX(height, inlink->h * sctx->scale + inh);
+        }
+
+    }
+
+    outlink->w = width;
+    outlink->h = height;
+    outlink->frame_rate = inlink0->frame_rate;
+    outlink->time_base = av_inv_q(outlink->frame_rate);
+    outlink->sample_aspect_ratio = inlink0->sample_aspect_ratio;
+
+    ret = init_framesync(ctx);
+
+    if (ret < 0)
+        return ret;
+
+    return ff_qsvvpp_create(ctx, &sctx->qsv, &sctx->qsv_param);
+}
+
+/*
+ * Callback for qsvvpp
+ * @Note: qsvvpp composition does not generate PTS for result frame.
+ *        so we assign the PTS from framesync to the output frame.
+ */
+
+static int filter_callback(AVFilterLink *outlink, AVFrame *frame)
+{
+    QSVStackContext *sctx = outlink->src->priv;
+
+    frame->pts = av_rescale_q(sctx->fs.pts,
+                              sctx->fs.time_base, outlink->time_base);
+    return ff_filter_frame(outlink, frame);
+}
+
+
+static int stack_qsv_init(AVFilterContext *ctx)
+{
+    QSVStackContext *sctx = ctx->priv;
+    int i, ret;
+
+    if (!strcmp(ctx->filter->name, "hstack_qsv"))
+        sctx->mode = QSV_STACK_H;
+    else if (!strcmp(ctx->filter->name, "vstack_qsv"))
+        sctx->mode = QSV_STACK_V;
+    else {
+        av_assert0(strcmp(ctx->filter->name, "xstack_qsv") == 0);
+        sctx->mode = QSV_STACK_X;
+
+        if (strcmp(sctx->fillcolor_str, "none") &&
+            av_parse_color(sctx->fillcolor, sctx->fillcolor_str, -1, ctx) >= 0) {
+            sctx->fillcolor_enable = 1;
+        } else {
+            sctx->fillcolor_enable = 0;
+        }
+
+        if (!sctx->layout) {
+            if (sctx->nb_inputs == 2) {
+                sctx->layout = av_strdup("0_0|w0_0");
+
+                if (!sctx->layout)
+                    return AVERROR(ENOMEM);
+            } else {
+                av_log(ctx, AV_LOG_ERROR, "No layout specified.\n");
+
+                return AVERROR(EINVAL);
+            }
+        }
+    }
+
+    for (i = 0; i < sctx->nb_inputs; i++) {
+        AVFilterPad pad = { 0 };
+
+        pad.type = AVMEDIA_TYPE_VIDEO;
+        pad.name = av_asprintf("input%d", i);
+
+        if (!pad.name)
+            return AVERROR(ENOMEM);
+
+        if ((ret = ff_insert_inpad(ctx, i, &pad)) < 0) {
+            av_freep(&pad.name);
+
+            return ret;
+        }
+    }
+
+    /* fill composite config */
+    sctx->comp_conf.Header.BufferId = MFX_EXTBUFF_VPP_COMPOSITE;
+    sctx->comp_conf.Header.BufferSz = sizeof(sctx->comp_conf);
+    sctx->comp_conf.NumInputStream = sctx->nb_inputs;
+    sctx->comp_conf.InputStream = av_mallocz_array(sctx->nb_inputs,
+                                                  sizeof(*sctx->comp_conf.InputStream));
+    if (!sctx->comp_conf.InputStream)
+        return AVERROR(ENOMEM);
+
+    /* initialize QSVVPP params */
+    sctx->qsv_param.filter_frame = filter_callback;
+    sctx->qsv_param.ext_buf = av_mallocz(sizeof(*sctx->qsv_param.ext_buf));
+
+    if (!sctx->qsv_param.ext_buf)
+        return AVERROR(ENOMEM);
+
+    sctx->qsv_param.ext_buf[0] = (mfxExtBuffer *)&sctx->comp_conf;
+    sctx->qsv_param.num_ext_buf = 1;
+    sctx->qsv_param.num_crop = 0;
+
+    return 0;
+}
+
+static av_cold void stack_qsv_uninit(AVFilterContext *ctx)
+{
+    QSVStackContext *sctx = ctx->priv;
+    int i;
+
+    ff_qsvvpp_free(&sctx->qsv);
+    ff_framesync_uninit(&sctx->fs);
+    av_freep(&sctx->comp_conf.InputStream);
+    av_freep(&sctx->qsv_param.ext_buf);
+
+    for (i = 0; i < ctx->nb_inputs; i++)
+        av_freep(&ctx->input_pads[i].name);
+}
+
+static int stack_qsv_activate(AVFilterContext *ctx)
+{
+    QSVStackContext *sctx = ctx->priv;
+    return ff_framesync_activate(&sctx->fs);
+}
+
+static int stack_qsv_query_formats(AVFilterContext *ctx)
+{
+    static const enum AVPixelFormat pixel_formats[] = {
+        AV_PIX_FMT_NV12,
+        AV_PIX_FMT_P010,
+        AV_PIX_FMT_QSV,
+        AV_PIX_FMT_NONE,
+    };
+    AVFilterFormats *pix_fmts = ff_make_format_list(pixel_formats);
+
+    return ff_set_common_formats(ctx, pix_fmts);
+}
+
+static const AVFilterPad stack_qsv_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = config_output,
+    },
+
+    { NULL }
+};
+
+static const AVOption stack_qsv_options[] = {
+    { "inputs", "set number of inputs", OFFSET(nb_inputs), AV_OPT_TYPE_INT, { .i64 = 2 }, 2, 72, .flags = FLAGS },
+    { "shortest", "force termination when the shortest input terminates", OFFSET(shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
+    { "scale", "set scale factor", OFFSET(scale),  AV_OPT_TYPE_DOUBLE, { .dbl = 1.0  }, 0.125, 8, FLAGS },
+    { NULL }
+};
+
+#define hstack_qsv_options stack_qsv_options
+AVFILTER_DEFINE_CLASS(hstack_qsv);
+
+const AVFilter ff_vf_hstack_qsv = {
+    .name           = "hstack_qsv",
+    .description    = NULL_IF_CONFIG_SMALL("Quick Sync Video hstack."),
+    .priv_size      = sizeof(QSVStackContext),
+    .priv_class     = &hstack_qsv_class,
+    .query_formats  = stack_qsv_query_formats,
+    .outputs        = stack_qsv_outputs,
+    .init           = stack_qsv_init,
+    .uninit         = stack_qsv_uninit,
+    .activate       = stack_qsv_activate,
+    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
+    .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,
+};
+
+#define vstack_qsv_options stack_qsv_options
+AVFILTER_DEFINE_CLASS(vstack_qsv);
+
+const AVFilter ff_vf_vstack_qsv = {
+    .name           = "vstack_qsv",
+    .description    = NULL_IF_CONFIG_SMALL("Quick Sync Video vstack."),
+    .priv_size      = sizeof(QSVStackContext),
+    .priv_class     = &vstack_qsv_class,
+    .query_formats  = stack_qsv_query_formats,
+    .outputs        = stack_qsv_outputs,
+    .init           = stack_qsv_init,
+    .uninit         = stack_qsv_uninit,
+    .activate       = stack_qsv_activate,
+    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
+    .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,
+};
+
+static const AVOption xstack_qsv_options[] = {
+    { "inputs", "set number of inputs", OFFSET(nb_inputs), AV_OPT_TYPE_INT, { .i64 = 2 }, 2, 72, .flags = FLAGS },
+    { "layout", "set custom layout", OFFSET(layout), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, .flags = FLAGS },
+    { "shortest", "force termination when the shortest input terminates", OFFSET(shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
+    { "fill",  "set the color for unused pixels", OFFSET(fillcolor_str), AV_OPT_TYPE_STRING, {.str = "none"}, .flags = FLAGS },
+    { "scale", "set scale factor", OFFSET(scale),  AV_OPT_TYPE_DOUBLE, { .dbl = 1.0  }, 0.125, 8, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(xstack_qsv);
+
+const AVFilter ff_vf_xstack_qsv = {
+    .name           = "xstack_qsv",
+    .description    = NULL_IF_CONFIG_SMALL("Quick Sync Video xstack."),
+    .priv_size      = sizeof(QSVStackContext),
+    .priv_class     = &xstack_qsv_class,
+    .query_formats  = stack_qsv_query_formats,
+    .outputs        = stack_qsv_outputs,
+    .init           = stack_qsv_init,
+    .uninit         = stack_qsv_uninit,
+    .activate       = stack_qsv_activate,
+    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
+    .flags          = AVFILTER_FLAG_DYNAMIC_INPUTS,
+};