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[FFmpeg-devel] avfilter: add pad opencl filter

Message ID 20200210120307.12503-1-onemda@gmail.com
State New
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Series [FFmpeg-devel] avfilter: add pad opencl filter
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andriy/ffmpeg-patchwork success Make finished
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Commit Message

Paul B Mahol Feb. 10, 2020, 12:03 p.m. UTC
Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 configure                   |   1 +
 doc/filters.texi            |  77 +++++++
 libavfilter/Makefile        |   1 +
 libavfilter/allfilters.c    |   1 +
 libavfilter/opencl/pad.cl   |  36 ++++
 libavfilter/opencl_source.h |   1 +
 libavfilter/vf_pad_opencl.c | 397 ++++++++++++++++++++++++++++++++++++
 7 files changed, 514 insertions(+)
 create mode 100644 libavfilter/opencl/pad.cl
 create mode 100644 libavfilter/vf_pad_opencl.c

Comments

Paul B Mahol Feb. 13, 2020, 7:02 p.m. UTC | #1
Will apply.

On 2/10/20, Paul B Mahol <onemda@gmail.com> wrote:
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>  configure                   |   1 +
>  doc/filters.texi            |  77 +++++++
>  libavfilter/Makefile        |   1 +
>  libavfilter/allfilters.c    |   1 +
>  libavfilter/opencl/pad.cl   |  36 ++++
>  libavfilter/opencl_source.h |   1 +
>  libavfilter/vf_pad_opencl.c | 397 ++++++++++++++++++++++++++++++++++++
>  7 files changed, 514 insertions(+)
>  create mode 100644 libavfilter/opencl/pad.cl
>  create mode 100644 libavfilter/vf_pad_opencl.c
Mark Thompson Feb. 13, 2020, 11:21 p.m. UTC | #2
On 10/02/2020 12:03, Paul B Mahol wrote:
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>  configure                   |   1 +
>  doc/filters.texi            |  77 +++++++
>  libavfilter/Makefile        |   1 +
>  libavfilter/allfilters.c    |   1 +
>  libavfilter/opencl/pad.cl   |  36 ++++
>  libavfilter/opencl_source.h |   1 +
>  libavfilter/vf_pad_opencl.c | 397 ++++++++++++++++++++++++++++++++++++
>  7 files changed, 514 insertions(+)
>  create mode 100644 libavfilter/opencl/pad.cl
>  create mode 100644 libavfilter/vf_pad_opencl.c
> 
> ...
> +
> +The @var{x} expression can reference the value set by the @var{y}
> +expression, and vice versa.
> +
> +The default value of @var{x} and @var{y} is 0.
> +
> +If @var{x} or @var{y} evaluate to a negative number, they'll be changed
> +so the input image is centered on the padded area.
> +
> +@item color
> +Specify the color of the padded area. For the syntax of this option,
> +check the @ref{color syntax,,"Color" section in the ffmpeg-utils
> +manual,ffmpeg-utils}.
> +
> +@item aspect
> +Pad to aspect instead to a resolution.

Funny phrasing.  "Pad to an aspect ratio instead of to a resolution.", maybe.

> +@end table
> +
> +The value for the @var{width}, @var{height}, @var{x}, and @var{y}
> +options are expressions containing the following constants:
> +
> +@table @option
> +@item in_w
> +@item in_h
> +The input video width and height.
> +
> +@item iw
> +@item ih
> +These are the same as @var{in_w} and @var{in_h}.
> +
> ...
> +
> +static int pad_opencl_init(AVFilterContext *avctx, AVFrame *input_frame)
> +{
> +    PadOpenCLContext *ctx = avctx->priv;
> +    AVHWFramesContext *input_frames_ctx = (AVHWFramesContext *)input_frame->hw_frames_ctx->data;
> +    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(input_frames_ctx->sw_format);
> +    uint8_t rgba_map[4];
> +    cl_int cle;
> +    int err;
> +
> +    ff_fill_rgba_map(rgba_map, input_frames_ctx->sw_format);

Ah, cute.  It's nice that a function already exists for this case :)

> +    ctx->is_rgb = !!(desc->flags & AV_PIX_FMT_FLAG_RGB);
> +    ctx->is_packed = !(desc->flags & AV_PIX_FMT_FLAG_PLANAR);
> +    ctx->hsub = desc->log2_chroma_w;
> +    ctx->vsub = desc->log2_chroma_h;
> +
> +    err = ff_opencl_filter_load_program(avctx, &ff_opencl_source_pad, 1);
> +    if (err < 0)
> +        goto fail;
> +
> ...

I tested a bit on Mali and everything else LGTM.

Thanks,

- Mark
diff mbox series

Patch

diff --git a/configure b/configure
index 51cdc7b2cb..ab761c7183 100755
--- a/configure
+++ b/configure
@@ -3535,6 +3535,7 @@  overlay_qsv_filter_deps="libmfx"
 overlay_qsv_filter_select="qsvvpp"
 overlay_vulkan_filter_deps="vulkan libglslang"
 owdenoise_filter_deps="gpl"
+pad_opencl_filter_deps="opencl"
 pan_filter_deps="swresample"
 perspective_filter_deps="gpl"
 phase_filter_deps="gpl"
diff --git a/doc/filters.texi b/doc/filters.texi
index bdc5700973..1791ede41a 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -21144,6 +21144,83 @@  The inputs have same memory layout for color channels , the overlay has addition
 
 @end itemize
 
+@section pad_opencl
+
+Add paddings to the input image, and place the original input at the
+provided @var{x}, @var{y} coordinates.
+
+It accepts the following options:
+
+@table @option
+@item width, w
+@item height, h
+Specify an expression for the size of the output image with the
+paddings added. If the value for @var{width} or @var{height} is 0, the
+corresponding input size is used for the output.
+
+The @var{width} expression can reference the value set by the
+@var{height} expression, and vice versa.
+
+The default value of @var{width} and @var{height} is 0.
+
+@item x
+@item y
+Specify the offsets to place the input image at within the padded area,
+with respect to the top/left border of the output image.
+
+The @var{x} expression can reference the value set by the @var{y}
+expression, and vice versa.
+
+The default value of @var{x} and @var{y} is 0.
+
+If @var{x} or @var{y} evaluate to a negative number, they'll be changed
+so the input image is centered on the padded area.
+
+@item color
+Specify the color of the padded area. For the syntax of this option,
+check the @ref{color syntax,,"Color" section in the ffmpeg-utils
+manual,ffmpeg-utils}.
+
+@item aspect
+Pad to aspect instead to a resolution.
+@end table
+
+The value for the @var{width}, @var{height}, @var{x}, and @var{y}
+options are expressions containing the following constants:
+
+@table @option
+@item in_w
+@item in_h
+The input video width and height.
+
+@item iw
+@item ih
+These are the same as @var{in_w} and @var{in_h}.
+
+@item out_w
+@item out_h
+The output width and height (the size of the padded area), as
+specified by the @var{width} and @var{height} expressions.
+
+@item ow
+@item oh
+These are the same as @var{out_w} and @var{out_h}.
+
+@item x
+@item y
+The x and y offsets as specified by the @var{x} and @var{y}
+expressions, or NAN if not yet specified.
+
+@item a
+same as @var{iw} / @var{ih}
+
+@item sar
+input sample aspect ratio
+
+@item dar
+input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
+@end table
+
 @section prewitt_opencl
 
 Apply the Prewitt operator (@url{https://en.wikipedia.org/wiki/Prewitt_operator}) to input video stream.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index cc00e2c4ac..089880a39d 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -329,6 +329,7 @@  OBJS-$(CONFIG_OVERLAY_QSV_FILTER)            += vf_overlay_qsv.o framesync.o
 OBJS-$(CONFIG_OVERLAY_VULKAN_FILTER)         += vf_overlay_vulkan.o vulkan.o
 OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o
 OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
+OBJS-$(CONFIG_PAD_OPENCL_FILTER)             += vf_pad_opencl.o opencl.o opencl/pad.o
 OBJS-$(CONFIG_PALETTEGEN_FILTER)             += vf_palettegen.o
 OBJS-$(CONFIG_PALETTEUSE_FILTER)             += vf_paletteuse.o framesync.o
 OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 01a7a8bf9f..88ebd121ad 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -313,6 +313,7 @@  extern AVFilter ff_vf_overlay_qsv;
 extern AVFilter ff_vf_overlay_vulkan;
 extern AVFilter ff_vf_owdenoise;
 extern AVFilter ff_vf_pad;
+extern AVFilter ff_vf_pad_opencl;
 extern AVFilter ff_vf_palettegen;
 extern AVFilter ff_vf_paletteuse;
 extern AVFilter ff_vf_perms;
diff --git a/libavfilter/opencl/pad.cl b/libavfilter/opencl/pad.cl
new file mode 100644
index 0000000000..e8dd6d6e42
--- /dev/null
+++ b/libavfilter/opencl/pad.cl
@@ -0,0 +1,36 @@ 
+/*
+ * 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
+ */
+
+const sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE |
+                          CLK_FILTER_NEAREST;
+
+__kernel void pad (
+    __read_only  image2d_t src,
+    __write_only image2d_t dst,
+    float4 color,
+    int2 xy)
+{
+    int2 size_src = get_image_dim(src);
+    int2 loc = (int2)(get_global_id(0), get_global_id(1));
+    int2 src_pos = (int2)(get_global_id(0) - xy.x, get_global_id(1) - xy.y);
+    float4 pixel = loc.x >= size_src.x + xy.x ||
+                   loc.y >= size_src.y + xy.y ||
+                   loc.x < xy.x ||
+                   loc.y < xy.y ? color : read_imagef(src, sampler, src_pos);
+    write_imagef(dst, loc, pixel);
+}
diff --git a/libavfilter/opencl_source.h b/libavfilter/opencl_source.h
index 4e262672ad..7e8133090e 100644
--- a/libavfilter/opencl_source.h
+++ b/libavfilter/opencl_source.h
@@ -27,6 +27,7 @@  extern const char *ff_opencl_source_deshake;
 extern const char *ff_opencl_source_neighbor;
 extern const char *ff_opencl_source_nlmeans;
 extern const char *ff_opencl_source_overlay;
+extern const char *ff_opencl_source_pad;
 extern const char *ff_opencl_source_tonemap;
 extern const char *ff_opencl_source_transpose;
 extern const char *ff_opencl_source_unsharp;
diff --git a/libavfilter/vf_pad_opencl.c b/libavfilter/vf_pad_opencl.c
new file mode 100644
index 0000000000..1129c40c60
--- /dev/null
+++ b/libavfilter/vf_pad_opencl.c
@@ -0,0 +1,397 @@ 
+/*
+ * 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/colorspace.h"
+#include "libavutil/eval.h"
+#include "libavutil/opt.h"
+#include "libavutil/imgutils.h"
+#include "avfilter.h"
+#include "drawutils.h"
+#include "formats.h"
+#include "internal.h"
+#include "opencl.h"
+#include "opencl_source.h"
+#include "video.h"
+
+static const char *const var_names[] = {
+    "in_w",   "iw",
+    "in_h",   "ih",
+    "out_w",  "ow",
+    "out_h",  "oh",
+    "x",
+    "y",
+    "a",
+    "sar",
+    "dar",
+    NULL
+};
+
+enum var_name {
+    VAR_IN_W,   VAR_IW,
+    VAR_IN_H,   VAR_IH,
+    VAR_OUT_W,  VAR_OW,
+    VAR_OUT_H,  VAR_OH,
+    VAR_X,
+    VAR_Y,
+    VAR_A,
+    VAR_SAR,
+    VAR_DAR,
+    VARS_NB
+};
+
+typedef struct PadOpenCLContext {
+    OpenCLFilterContext ocf;
+    int initialized;
+    int is_rgb;
+    int is_packed;
+    int hsub, vsub;
+
+    char *w_expr;
+    char *h_expr;
+    char *x_expr;
+    char *y_expr;
+    AVRational aspect;
+
+    cl_command_queue command_queue;
+    cl_kernel kernel_pad;
+
+    int w, h;
+    int x, y;
+    uint8_t pad_rgba[4];
+    uint8_t pad_color[4];
+    cl_float4 pad_color_float;
+    cl_int2 pad_pos;
+} PadOpenCLContext;
+
+static int pad_opencl_init(AVFilterContext *avctx, AVFrame *input_frame)
+{
+    PadOpenCLContext *ctx = avctx->priv;
+    AVHWFramesContext *input_frames_ctx = (AVHWFramesContext *)input_frame->hw_frames_ctx->data;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(input_frames_ctx->sw_format);
+    uint8_t rgba_map[4];
+    cl_int cle;
+    int err;
+
+    ff_fill_rgba_map(rgba_map, input_frames_ctx->sw_format);
+    ctx->is_rgb = !!(desc->flags & AV_PIX_FMT_FLAG_RGB);
+    ctx->is_packed = !(desc->flags & AV_PIX_FMT_FLAG_PLANAR);
+    ctx->hsub = desc->log2_chroma_w;
+    ctx->vsub = desc->log2_chroma_h;
+
+    err = ff_opencl_filter_load_program(avctx, &ff_opencl_source_pad, 1);
+    if (err < 0)
+        goto fail;
+
+    ctx->command_queue = clCreateCommandQueue(
+        ctx->ocf.hwctx->context,
+        ctx->ocf.hwctx->device_id,
+        0,
+        &cle
+    );
+
+    if (ctx->is_rgb) {
+        ctx->pad_color[rgba_map[0]] = ctx->pad_rgba[0];
+        ctx->pad_color[rgba_map[1]] = ctx->pad_rgba[1];
+        ctx->pad_color[rgba_map[2]] = ctx->pad_rgba[2];
+        ctx->pad_color[rgba_map[3]] = ctx->pad_rgba[3];
+    } else {
+        ctx->pad_color[0] = RGB_TO_Y_BT709(ctx->pad_rgba[0], ctx->pad_rgba[1], ctx->pad_rgba[2]);
+        ctx->pad_color[1] = RGB_TO_U_BT709(ctx->pad_rgba[0], ctx->pad_rgba[1], ctx->pad_rgba[2], 0);
+        ctx->pad_color[2] = RGB_TO_V_BT709(ctx->pad_rgba[0], ctx->pad_rgba[1], ctx->pad_rgba[2], 0);
+        ctx->pad_color[3] = ctx->pad_rgba[3];
+    }
+
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create OpenCL command queue %d.\n", cle);
+
+    ctx->kernel_pad = clCreateKernel(ctx->ocf.program, "pad", &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create pad kernel: %d.\n", cle);
+
+    for (int i = 0; i < 4; ++i) {
+        ctx->pad_color_float.s[i] = (float)ctx->pad_color[i] / 255.0;
+    }
+
+    ctx->pad_pos.s[0] = ctx->x;
+    ctx->pad_pos.s[1] = ctx->y;
+
+    ctx->initialized = 1;
+    return 0;
+
+fail:
+    if (ctx->command_queue)
+        clReleaseCommandQueue(ctx->command_queue);
+    if (ctx->kernel_pad)
+        clReleaseKernel(ctx->kernel_pad);
+    return err;
+}
+
+static int filter_frame(AVFilterLink *link, AVFrame *input_frame)
+{
+    AVFilterContext *avctx = link->dst;
+    AVFilterLink *outlink = avctx->outputs[0];
+    PadOpenCLContext *pad_ctx = avctx->priv;
+    AVFrame *output_frame = NULL;
+    int err;
+    cl_int cle;
+    size_t global_work[2];
+    cl_mem src, dst;
+
+    if (!input_frame->hw_frames_ctx)
+        return AVERROR(EINVAL);
+
+    if (!pad_ctx->initialized) {
+        err = pad_opencl_init(avctx, input_frame);
+        if (err < 0)
+            goto fail;
+    }
+
+    output_frame = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+    if (!output_frame) {
+        err = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    for (int p = 0; p < FF_ARRAY_ELEMS(output_frame->data); p++) {
+        cl_float4 pad_color_float;
+        cl_int2 pad_pos;
+
+        if (pad_ctx->is_packed) {
+            pad_color_float = pad_ctx->pad_color_float;
+        } else {
+            pad_color_float.s[0] = pad_ctx->pad_color_float.s[p];
+            pad_color_float.s[1] = pad_ctx->pad_color_float.s[2];
+        }
+
+        if (p > 0 && p < 3) {
+            pad_pos.s[0] = pad_ctx->pad_pos.s[0] >> pad_ctx->hsub;
+            pad_pos.s[1] = pad_ctx->pad_pos.s[1] >> pad_ctx->vsub;
+        } else {
+            pad_pos.s[0] = pad_ctx->pad_pos.s[0];
+            pad_pos.s[1] = pad_ctx->pad_pos.s[1];
+        }
+
+        src = (cl_mem)input_frame->data[p];
+        dst = (cl_mem)output_frame->data[p];
+
+        if (!dst)
+            break;
+
+        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 0, cl_mem, &src);
+        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 1, cl_mem, &dst);
+        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 2, cl_float4, &pad_color_float);
+        CL_SET_KERNEL_ARG(pad_ctx->kernel_pad, 3, cl_int2, &pad_pos);
+
+        err = ff_opencl_filter_work_size_from_image(avctx, global_work, output_frame, p, 16);
+        if (err < 0)
+            goto fail;
+
+        cle = clEnqueueNDRangeKernel(pad_ctx->command_queue, pad_ctx->kernel_pad, 2, NULL,
+                                     global_work, NULL, 0, NULL, NULL);
+
+        CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue pad kernel: %d.\n", cle);
+    }
+
+    // Run queued kernel
+    cle = clFinish(pad_ctx->command_queue);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to finish command queue: %d.\n", cle);
+
+    err = av_frame_copy_props(output_frame, input_frame);
+    if (err < 0)
+        goto fail;
+
+    av_frame_free(&input_frame);
+
+    return ff_filter_frame(outlink, output_frame);
+
+fail:
+    clFinish(pad_ctx->command_queue);
+    av_frame_free(&input_frame);
+    av_frame_free(&output_frame);
+    return err;
+}
+
+static av_cold void pad_opencl_uninit(AVFilterContext *avctx)
+{
+    PadOpenCLContext *ctx = avctx->priv;
+    cl_int cle;
+
+    if (ctx->kernel_pad) {
+        cle = clReleaseKernel(ctx->kernel_pad);
+        if (cle != CL_SUCCESS)
+            av_log(avctx, AV_LOG_ERROR, "Failed to release "
+                   "kernel: %d.\n", cle);
+    }
+
+    if (ctx->command_queue) {
+        cle = clReleaseCommandQueue(ctx->command_queue);
+        if (cle != CL_SUCCESS)
+            av_log(avctx, AV_LOG_ERROR, "Failed to release "
+                   "command queue: %d.\n", cle);
+    }
+
+    ff_opencl_filter_uninit(avctx);
+}
+
+static int pad_opencl_config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *avctx = outlink->src;
+    AVFilterLink *inlink = avctx->inputs[0];
+    PadOpenCLContext *ctx = avctx->priv;
+    AVRational adjusted_aspect = ctx->aspect;
+    double var_values[VARS_NB], res;
+    int err, ret;
+    char *expr;
+
+    var_values[VAR_IN_W]  = var_values[VAR_IW] = inlink->w;
+    var_values[VAR_IN_H]  = var_values[VAR_IH] = inlink->h;
+    var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
+    var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
+    var_values[VAR_A]     = (double) inlink->w / inlink->h;
+    var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?
+        (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
+    var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];
+
+    av_expr_parse_and_eval(&res, (expr = ctx->w_expr),
+                           var_names, var_values,
+                           NULL, NULL, NULL, NULL, NULL, 0, ctx);
+    ctx->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
+    if ((ret = av_expr_parse_and_eval(&res, (expr = ctx->h_expr),
+                                      var_names, var_values,
+                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+        return ret;
+    ctx->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
+    if (!ctx->h)
+        var_values[VAR_OUT_H] = var_values[VAR_OH] = ctx->h = inlink->h;
+
+    /* evaluate the width again, as it may depend on the evaluated output height */
+    if ((ret = av_expr_parse_and_eval(&res, (expr = ctx->w_expr),
+                                      var_names, var_values,
+                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+        return ret;
+    ctx->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
+    if (!ctx->w)
+        var_values[VAR_OUT_W] = var_values[VAR_OW] = ctx->w = inlink->w;
+
+    if (adjusted_aspect.num && adjusted_aspect.den) {
+        adjusted_aspect = av_div_q(adjusted_aspect, inlink->sample_aspect_ratio);
+        if (ctx->h < av_rescale(ctx->w, adjusted_aspect.den, adjusted_aspect.num)) {
+            ctx->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = av_rescale(ctx->w, adjusted_aspect.den, adjusted_aspect.num);
+        } else {
+            ctx->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = av_rescale(ctx->h, adjusted_aspect.num, adjusted_aspect.den);
+        }
+    }
+
+    /* evaluate x and y */
+    av_expr_parse_and_eval(&res, (expr = ctx->x_expr),
+                           var_names, var_values,
+                           NULL, NULL, NULL, NULL, NULL, 0, ctx);
+    ctx->x = var_values[VAR_X] = res;
+    if ((ret = av_expr_parse_and_eval(&res, (expr = ctx->y_expr),
+                                      var_names, var_values,
+                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+        return ret;
+    ctx->y = var_values[VAR_Y] = res;
+    /* evaluate x again, as it may depend on the evaluated y value */
+    if ((ret = av_expr_parse_and_eval(&res, (expr = ctx->x_expr),
+                                      var_names, var_values,
+                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+        return ret;
+    ctx->x = var_values[VAR_X] = res;
+
+    if (ctx->x < 0 || ctx->x + inlink->w > ctx->w)
+        ctx->x = var_values[VAR_X] = (ctx->w - inlink->w) / 2;
+    if (ctx->y < 0 || ctx->y + inlink->h > ctx->h)
+        ctx->y = var_values[VAR_Y] = (ctx->h - inlink->h) / 2;
+
+    /* sanity check params */
+    if (ctx->w < inlink->w || ctx->h < inlink->h) {
+        av_log(ctx, AV_LOG_ERROR, "Padded dimensions cannot be smaller than input dimensions.\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (ctx->w > avctx->inputs[0]->w) {
+        ctx->ocf.output_width  = ctx->w;
+    } else {
+        ctx->ocf.output_width  = avctx->inputs[0]->w;
+    }
+
+    if (ctx->h > avctx->inputs[0]->h) {
+        ctx->ocf.output_height = ctx->h;
+    } else {
+        ctx->ocf.output_height = avctx->inputs[0]->h;
+    }
+
+    if (ctx->x + avctx->inputs[0]->w > ctx->ocf.output_width ||
+        ctx->y + avctx->inputs[0]->h > ctx->ocf.output_height) {
+        return AVERROR(EINVAL);
+    }
+
+    err = ff_opencl_filter_config_output(outlink);
+    if (err < 0)
+        return err;
+
+    return 0;
+}
+
+static const AVFilterPad pad_opencl_inputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+        .config_props = &ff_opencl_filter_config_input,
+    },
+    { NULL }
+};
+
+static const AVFilterPad pad_opencl_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+        .config_props = &pad_opencl_config_output,
+    },
+    { NULL }
+};
+
+#define OFFSET(x) offsetof(PadOpenCLContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+
+static const AVOption pad_opencl_options[] = {
+    { "width",  "set the pad area width",       OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, 0, 0, FLAGS },
+    { "w",      "set the pad area width",       OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, 0, 0, FLAGS },
+    { "height", "set the pad area height",      OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, 0, 0, FLAGS },
+    { "h",      "set the pad area height",      OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, 0, 0, FLAGS },
+    { "x",      "set the x offset for the input image position", OFFSET(x_expr), AV_OPT_TYPE_STRING, {.str = "0"}, 0, INT16_MAX, FLAGS },
+    { "y",      "set the y offset for the input image position", OFFSET(y_expr), AV_OPT_TYPE_STRING, {.str = "0"}, 0, INT16_MAX, FLAGS },
+    { "color", "set the color of the padded area border", OFFSET(pad_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, 0, 0, FLAGS },
+    { "aspect",  "pad to fit an aspect instead of a resolution", OFFSET(aspect), AV_OPT_TYPE_RATIONAL, {.dbl = 0}, 0, INT16_MAX, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(pad_opencl);
+
+AVFilter ff_vf_pad_opencl = {
+    .name           = "pad_opencl",
+    .description    = NULL_IF_CONFIG_SMALL("Pad the input video."),
+    .priv_size      = sizeof(PadOpenCLContext),
+    .priv_class     = &pad_opencl_class,
+    .init           = &ff_opencl_filter_init,
+    .uninit         = &pad_opencl_uninit,
+    .query_formats  = &ff_opencl_filter_query_formats,
+    .inputs         = pad_opencl_inputs,
+    .outputs        = pad_opencl_outputs,
+    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE
+};