lavfi/opencl: add nlmeans_opencl filter

Reviewed-by: Mark Thompson <sw@jkqxz.net>
Signed-off-by: Ruiling Song <ruiling.song@intel.com>

configure

@@ -3470,6 +3470,7 @@ mpdecimate_filter_select="pixelutils"
 minterpolate_filter_select="scene_sad"
 mptestsrc_filter_deps="gpl"
 negate_filter_deps="lut_filter"
+nlmeans_opencl_filter_deps="opencl"
 nnedi_filter_deps="gpl"
 ocr_filter_deps="libtesseract"
 ocv_filter_deps="libopencv"

doc/filters.texi

@@ -19350,6 +19350,10 @@ Make every semi-green pixel in the input transparent with some slight blending:
 @end example
 @end itemize
 
+@section nlmeans_opencl
+
+Non-local Means denoise filter through OpenCL, this filter accepts same options as @ref{nlmeans}.
+
 @section overlay_opencl
 
 Overlay one video on top of another.

libavfilter/Makefile

@@ -297,6 +297,7 @@ OBJS-$(CONFIG_MIX_FILTER)                    += vf_mix.o
 OBJS-$(CONFIG_MPDECIMATE_FILTER)             += vf_mpdecimate.o
 OBJS-$(CONFIG_NEGATE_FILTER)                 += vf_lut.o
 OBJS-$(CONFIG_NLMEANS_FILTER)                += vf_nlmeans.o
+OBJS-$(CONFIG_NLMEANS_OPENCL_FILTER)         += vf_nlmeans_opencl.o opencl.o opencl/nlmeans.o
 OBJS-$(CONFIG_NNEDI_FILTER)                  += vf_nnedi.o
 OBJS-$(CONFIG_NOFORMAT_FILTER)               += vf_format.o
 OBJS-$(CONFIG_NOISE_FILTER)                  += vf_noise.o

libavfilter/allfilters.c

@@ -282,6 +282,7 @@ extern AVFilter ff_vf_mix;
 extern AVFilter ff_vf_mpdecimate;
 extern AVFilter ff_vf_negate;
 extern AVFilter ff_vf_nlmeans;
+extern AVFilter ff_vf_nlmeans_opencl;
 extern AVFilter ff_vf_nnedi;
 extern AVFilter ff_vf_noformat;
 extern AVFilter ff_vf_noise;

libavfilter/opencl/nlmeans.cl

+/*
+ * 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_ADDRESS_CLAMP_TO_EDGE   |
+                           CLK_FILTER_NEAREST);
+
+kernel void horiz_sum(__global uint4 *integral_img,
+                      __read_only image2d_t src,
+                      int width,
+                      int height,
+                      int4 dx,
+                      int4 dy)
+{
+
+    int y = get_global_id(0);
+    int work_size = get_global_size(0);
+
+    uint4 sum = (uint4)(0);
+    float4 s2;
+    for (int i = 0; i < width; i++) {
+        float s1 = read_imagef(src, sampler, (int2)(i, y)).x;
+        s2.x = read_imagef(src, sampler, (int2)(i + dx.x, y + dy.x)).x;
+        s2.y = read_imagef(src, sampler, (int2)(i + dx.y, y + dy.y)).x;
+        s2.z = read_imagef(src, sampler, (int2)(i + dx.z, y + dy.z)).x;
+        s2.w = read_imagef(src, sampler, (int2)(i + dx.w, y + dy.w)).x;
+        sum += convert_uint4((s1 - s2) * (s1 - s2) * 255 * 255);
+        integral_img[y * width + i] = sum;
+    }
+}
+
+kernel void vert_sum(__global uint4 *integral_img,
+                     __global int *overflow,
+                     int width,
+                     int height)
+{
+    int x = get_global_id(0);
+    uint4 sum = 0;
+    for (int i = 0; i < height; i++) {
+        if (any((uint4)UINT_MAX - integral_img[i * width + x] < sum))
+            atomic_inc(overflow);
+        integral_img[i * width + x] += sum;
+        sum = integral_img[i * width + x];
+    }
+}
+
+kernel void weight_accum(global float *sum, global float *weight,
+                         global uint4 *integral_img, __read_only image2d_t src,
+                         int width, int height, int p, float h,
+                         int4 dx, int4 dy)
+{
+    // w(x) = integral_img(x-p, y-p) +
+    //        integral_img(x+p, y+p) -
+    //        integral_img(x+p, y-p) -
+    //        integral_img(x-p, y+p)
+    // total_sum[x] += w(x, y) * src(x + dx, y + dy)
+    // total_weight += w(x, y)
+
+    int x = get_global_id(0);
+    int y = get_global_id(1);
+    int4 xoff = x + dx;
+    int4 yoff = y + dy;
+    uint4 a = 0, b = 0, c = 0, d = 0;
+    uint4 src_pix = 0;
+
+    // out-of-bounding-box?
+    int oobb = (x - p) < 0 || (y - p) < 0 || (y + p) >= height || (x + p) >= width;
+
+    src_pix.x = (int)(255 * read_imagef(src, sampler, (int2)(xoff.x, yoff.x)).x);
+    src_pix.y = (int)(255 * read_imagef(src, sampler, (int2)(xoff.y, yoff.y)).x);
+    src_pix.z = (int)(255 * read_imagef(src, sampler, (int2)(xoff.z, yoff.z)).x);
+    src_pix.w = (int)(255 * read_imagef(src, sampler, (int2)(xoff.w, yoff.w)).x);
+    if (!oobb) {
+        a = integral_img[(y - p) * width + x - p];
+        b = integral_img[(y + p) * width + x - p];
+        c = integral_img[(y - p) * width + x + p];
+        d = integral_img[(y + p) * width + x + p];
+    }
+
+    float4 patch_diff = convert_float4(d + a - c - b);
+    float4 w = native_exp(-patch_diff / (h * h));
+    float w_sum = w.x + w.y + w.z + w.w;
+    weight[y * width + x] += w_sum;
+    sum[y * width + x] += dot(w, convert_float4(src_pix));
+}
+
+kernel void average(__write_only image2d_t dst,
+                    __read_only image2d_t src,
+                    global float *sum, global float *weight) {
+    int x = get_global_id(0);
+    int y = get_global_id(1);
+    int2 dim = get_image_dim(dst);
+
+    float w = weight[y * dim.x + x];
+    float s = sum[y * dim.x + x];
+    float src_pix = read_imagef(src, sampler, (int2)(x, y)).x;
+    float r = (s + src_pix * 255) / (1.0f + w) / 255.0f;
+    if (x < dim.x && y < dim.y)
+        write_imagef(dst, (int2)(x, y), (float4)(r, 0.0f, 0.0f, 1.0f));
+}

libavfilter/opencl_source.h

@@ -24,6 +24,7 @@ extern const char *ff_opencl_source_colorkey;
 extern const char *ff_opencl_source_colorspace_common;
 extern const char *ff_opencl_source_convolution;
 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_tonemap;
 extern const char *ff_opencl_source_transpose;

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   7
-#define LIBAVFILTER_VERSION_MINOR  53
+#define LIBAVFILTER_VERSION_MINOR  54
 #define LIBAVFILTER_VERSION_MICRO 101
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vf_nlmeans_opencl.c

+/*
+ * 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 <float.h>
+
+#include "libavutil/avassert.h"
+#include "libavutil/common.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/mem.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+
+#include "avfilter.h"
+#include "internal.h"
+#include "opencl.h"
+#include "opencl_source.h"
+#include "video.h"
+
+// TODO:
+//      the integral image may overflow 32bit, consider using 64bit
+
+static const enum AVPixelFormat supported_formats[] = {
+    AV_PIX_FMT_YUV420P,
+    AV_PIX_FMT_YUV444P,
+    AV_PIX_FMT_GBRP,
+};
+
+static int is_format_supported(enum AVPixelFormat fmt)
+{
+    int i;
+
+    for (i = 0; i < FF_ARRAY_ELEMS(supported_formats); i++)
+        if (supported_formats[i] == fmt)
+            return 1;
+    return 0;
+}
+
+typedef struct NLMeansOpenCLContext {
+    OpenCLFilterContext   ocf;
+    int                   initialised;
+    cl_kernel             vert_kernel;
+    cl_kernel             horiz_kernel;
+    cl_kernel             accum_kernel;
+    cl_kernel             average_kernel;
+    cl_mem                integral_img;
+    cl_mem                weight;
+    cl_mem                sum;
+    cl_mem                overflow; // overflow in integral image?
+    double                sigma;
+    float                 h;
+    int                   chroma_w;
+    int                   chroma_h;
+    int                   patch_size;
+    int                   patch_size_uv;
+    int                   research_size;
+    int                   research_size_uv;
+    cl_command_queue      command_queue;
+} NLMeansOpenCLContext;
+
+static int nlmeans_opencl_init(AVFilterContext *avctx, int width, int height)
+{
+    NLMeansOpenCLContext *ctx = avctx->priv;
+    cl_int cle;
+    int err;
+    int weight_buf_size = width * height * sizeof(float);
+
+    ctx->h = ctx->sigma * 10;
+    if (!(ctx->research_size & 1)) {
+        ctx->research_size |= 1;
+        av_log(avctx, AV_LOG_WARNING,
+               "research_size should be odd, set to %d",
+               ctx->research_size);
+    }
+
+    if (!(ctx->patch_size & 1)) {
+        ctx->patch_size |= 1;
+        av_log(avctx, AV_LOG_WARNING,
+               "patch_size should be odd, set to %d",
+               ctx->patch_size);
+    }
+
+    if (!ctx->research_size_uv)
+        ctx->research_size_uv = ctx->research_size;
+    if (!ctx->patch_size_uv)
+        ctx->patch_size_uv = ctx->patch_size;
+
+    err = ff_opencl_filter_load_program(avctx, &ff_opencl_source_nlmeans, 1);
+    if (err < 0)
+        goto fail;
+
+    ctx->command_queue = clCreateCommandQueue(ctx->ocf.hwctx->context,
+                                              ctx->ocf.hwctx->device_id,
+                                              0, &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create OpenCL "
+                     "command queue %d.\n", cle);
+
+    ctx->vert_kernel = clCreateKernel(ctx->ocf.program,
+                                      "vert_sum", &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "vert_sum kernel %d.\n", cle);
+
+    ctx->horiz_kernel = clCreateKernel(ctx->ocf.program,
+                                       "horiz_sum", &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "horiz_sum kernel %d.\n", cle);
+
+    ctx->accum_kernel = clCreateKernel(ctx->ocf.program,
+                                       "weight_accum", &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "accum kernel %d.\n", cle);
+
+    ctx->average_kernel = clCreateKernel(ctx->ocf.program,
+                                         "average", &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "average kernel %d.\n", cle);
+
+    ctx->integral_img = clCreateBuffer(ctx->ocf.hwctx->context, 0,
+                                       4 * width * height * sizeof(cl_int),
+                                       NULL, &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "integral image %d.\n", cle);
+
+    ctx->weight = clCreateBuffer(ctx->ocf.hwctx->context, 0,
+                                 weight_buf_size, NULL, &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "weight buffer %d.\n", cle);
+
+    ctx->sum = clCreateBuffer(ctx->ocf.hwctx->context, 0,
+                              weight_buf_size, NULL, &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "sum buffer %d.\n", cle);
+
+    ctx->overflow = clCreateBuffer(ctx->ocf.hwctx->context, 0,
+                                   sizeof(cl_int), NULL, &cle);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create "
+                     "overflow buffer %d.\n", cle);
+
+    ctx->initialised = 1;
+    return 0;
+
+fail:
+    CL_RELEASE_KERNEL(ctx->vert_kernel);
+    CL_RELEASE_KERNEL(ctx->horiz_kernel);
+    CL_RELEASE_KERNEL(ctx->accum_kernel);
+    CL_RELEASE_KERNEL(ctx->average_kernel);
+
+    CL_RELEASE_MEMORY(ctx->integral_img);
+    CL_RELEASE_MEMORY(ctx->weight);
+    CL_RELEASE_MEMORY(ctx->sum);
+    CL_RELEASE_MEMORY(ctx->overflow);
+
+    CL_RELEASE_QUEUE(ctx->command_queue);
+    return err;
+}
+
+static int nlmeans_plane(AVFilterContext *avctx, cl_mem dst, cl_mem src,
+                         cl_int width, cl_int height, cl_int p, cl_int r)
+{
+    NLMeansOpenCLContext *ctx = avctx->priv;
+    const float zero = 0.0f;
+    const size_t worksize1[] = {height};
+    const size_t worksize2[] = {width};
+    const size_t worksize3[2] = {width, height};
+    int i, dx, dy, err = 0, weight_buf_size;
+    cl_int cle;
+    int nb_pixel, *tmp = NULL, idx = 0;
+    cl_int *dxdy = NULL;
+
+    weight_buf_size = width * height * sizeof(float);
+    cle = clEnqueueFillBuffer(ctx->command_queue, ctx->weight,
+                              &zero, sizeof(float), 0, weight_buf_size,
+                              0, NULL, NULL);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to fill weight buffer: %d.\n",
+                     cle);
+    cle = clEnqueueFillBuffer(ctx->command_queue, ctx->sum,
+                              &zero, sizeof(float), 0, weight_buf_size,
+                              0, NULL, NULL);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to fill sum buffer: %d.\n",
+                     cle);
+
+    nb_pixel = (2 * r + 1) * (2 * r + 1) - 1;
+    dxdy = av_malloc(nb_pixel * 2 * sizeof(cl_int));
+    tmp = av_malloc(nb_pixel * 2 * sizeof(int));
+
+    if (!dxdy || !tmp)
+        goto fail;
+
+    for (dx = -r; dx <= r; dx++) {
+        for (dy = -r; dy <= r; dy++) {
+            if (dx || dy) {
+                tmp[idx++] = dx;
+                tmp[idx++] = dy;
+            }
+        }
+    }
+    // repack dx/dy seperately, as we want to do four pairs of dx/dy in a batch
+    for (i = 0; i < nb_pixel / 4; i++) {
+        dxdy[i * 8] = tmp[i * 8];         // dx0
+        dxdy[i * 8 + 1] = tmp[i * 8 + 2]; // dx1
+        dxdy[i * 8 + 2] = tmp[i * 8 + 4]; // dx2
+        dxdy[i * 8 + 3] = tmp[i * 8 + 6]; // dx3
+        dxdy[i * 8 + 4] = tmp[i * 8 + 1]; // dy0
+        dxdy[i * 8 + 5] = tmp[i * 8 + 3]; // dy1
+        dxdy[i * 8 + 6] = tmp[i * 8 + 5]; // dy2
+        dxdy[i * 8 + 7] = tmp[i * 8 + 7]; // dy3
+    }
+    av_freep(&tmp);
+
+    for (i = 0; i < nb_pixel / 4; i++) {
+        cl_int *dx_cur = dxdy + 8 * i;
+        cl_int *dy_cur = dxdy + 8 * i + 4;
+
+        // horizontal pass
+        // integral(x,y) = sum([u(v,y) - u(v+dx,y+dy)]^2) for v in [0, x]
+        CL_SET_KERNEL_ARG(ctx->horiz_kernel, 0, cl_mem, &ctx->integral_img);
+        CL_SET_KERNEL_ARG(ctx->horiz_kernel, 1, cl_mem, &src);
+        CL_SET_KERNEL_ARG(ctx->horiz_kernel, 2, cl_int, &width);
+        CL_SET_KERNEL_ARG(ctx->horiz_kernel, 3, cl_int, &height);
+        CL_SET_KERNEL_ARG(ctx->horiz_kernel, 4, cl_int4, dx_cur);
+        CL_SET_KERNEL_ARG(ctx->horiz_kernel, 5, cl_int4, dy_cur);
+        cle = clEnqueueNDRangeKernel(ctx->command_queue, ctx->horiz_kernel, 1,
+                               NULL, worksize1, NULL, 0, NULL, NULL);
+        CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue horiz_kernel: %d.\n",
+                         cle);
+        // vertical pass
+        // integral(x, y) = sum(integral(x, v)) for v in [0, y]
+        CL_SET_KERNEL_ARG(ctx->vert_kernel, 0, cl_mem, &ctx->integral_img);
+        CL_SET_KERNEL_ARG(ctx->vert_kernel, 1, cl_mem, &ctx->overflow);
+        CL_SET_KERNEL_ARG(ctx->vert_kernel, 2, cl_int, &width);
+        CL_SET_KERNEL_ARG(ctx->vert_kernel, 3, cl_int, &height);
+        cle = clEnqueueNDRangeKernel(ctx->command_queue, ctx->vert_kernel,
+                                     1, NULL, worksize2, NULL, 0, NULL, NULL);
+        CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue vert_kernel: %d.\n",
+                         cle);
+
+        // accumulate weights
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 0, cl_mem, &ctx->sum);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 1, cl_mem, &ctx->weight);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 2, cl_mem, &ctx->integral_img);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 3, cl_mem, &src);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 4, cl_int, &width);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 5, cl_int, &height);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 6, cl_int, &p);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 7, cl_float, &ctx->h);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 8, cl_int4, dx_cur);
+        CL_SET_KERNEL_ARG(ctx->accum_kernel, 9, cl_int4, dy_cur);
+        cle = clEnqueueNDRangeKernel(ctx->command_queue, ctx->accum_kernel,
+                                     2, NULL, worksize3, NULL, 0, NULL, NULL);
+        CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue kernel: %d.\n", cle);
+    }
+    av_freep(&dxdy);
+
+    // average
+    CL_SET_KERNEL_ARG(ctx->average_kernel, 0, cl_mem, &dst);
+    CL_SET_KERNEL_ARG(ctx->average_kernel, 1, cl_mem, &src);
+    CL_SET_KERNEL_ARG(ctx->average_kernel, 2, cl_mem, &ctx->sum);
+    CL_SET_KERNEL_ARG(ctx->average_kernel, 3, cl_mem, &ctx->weight);
+    cle = clEnqueueNDRangeKernel(ctx->command_queue, ctx->average_kernel, 2,
+                                 NULL, worksize3, NULL, 0, NULL, NULL);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to enqueue average kernel: %d.\n",
+                     cle);
+    cle = clFlush(ctx->command_queue);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to flush command queue: %d.\n", cle);
+fail:
+    if (tmp)
+        av_freep(&tmp);
+    if (dxdy)
+        av_freep(&dxdy);
+    return err;
+}
+
+static int nlmeans_opencl_filter_frame(AVFilterLink *inlink, AVFrame *input)
+{
+    AVFilterContext    *avctx = inlink->dst;
+    AVFilterLink     *outlink = avctx->outputs[0];
+    NLMeansOpenCLContext *ctx = avctx->priv;
+    AVFrame *output = NULL;
+    AVHWFramesContext *input_frames_ctx;
+    const AVPixFmtDescriptor *desc;
+    enum AVPixelFormat in_format;
+    cl_mem src, dst;
+    const cl_int zero = 0;
+    int w, h, err, cle, overflow, p, patch, research;
+
+    av_log(ctx, AV_LOG_DEBUG, "Filter input: %s, %ux%u (%"PRId64").\n",
+           av_get_pix_fmt_name(input->format),
+           input->width, input->height, input->pts);
+
+    if (!input->hw_frames_ctx)
+        return AVERROR(EINVAL);
+    input_frames_ctx = (AVHWFramesContext*)input->hw_frames_ctx->data;
+    in_format = input_frames_ctx->sw_format;
+
+    output = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+    if (!output) {
+        err = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    err = av_frame_copy_props(output, input);
+    if (err < 0)
+        goto fail;
+
+    if (!ctx->initialised) {
+        desc = av_pix_fmt_desc_get(in_format);
+        if (!is_format_supported(in_format)) {
+            err = AVERROR(EINVAL);
+            av_log(avctx, AV_LOG_ERROR, "input format %s not supported\n",
+                   av_get_pix_fmt_name(in_format));
+            goto fail;
+        }
+        ctx->chroma_w = AV_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);
+        ctx->chroma_h = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
+
+        err = nlmeans_opencl_init(avctx, inlink->w, inlink->h);
+        if (err < 0)
+            goto fail;
+    }
+
+    cle = clEnqueueWriteBuffer(ctx->command_queue, ctx->overflow, CL_FALSE,
+                               0, sizeof(cl_int), &zero, 0, NULL, NULL);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to initialize overflow"
+                     "detection buffer %d.\n", cle);
+
+    for (p = 0; p < FF_ARRAY_ELEMS(output->data); p++) {
+        src = (cl_mem) input->data[p];
+        dst = (cl_mem) output->data[p];
+
+        if (!dst)
+            break;
+        av_assert0(src);
+        w = p ? ctx->chroma_w : inlink->w;
+        h = p ? ctx->chroma_h : inlink->h;
+        patch = (p ? ctx->patch_size_uv : ctx->patch_size) / 2;
+        research = (p ? ctx->research_size_uv : ctx->research_size) / 2;
+        err = nlmeans_plane(avctx, dst, src, w, h, patch, research);
+        if (err < 0)
+            goto fail;
+    }
+    // overflow occurred?
+    cle = clEnqueueReadBuffer(ctx->command_queue, ctx->overflow, CL_FALSE,
+                              0, sizeof(cl_int), &overflow, 0, NULL, NULL);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to read overflow: %d.\n", cle);
+
+    cle = clFinish(ctx->command_queue);
+    CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to finish kernel: %d.\n", cle);
+
+    if (overflow > 0)
+        av_log(avctx, AV_LOG_ERROR, "integral image overflow %d\n", overflow);
+
+    av_frame_free(&input);
+
+    av_log(ctx, AV_LOG_DEBUG, "Filter output: %s, %ux%u (%"PRId64").\n",
+           av_get_pix_fmt_name(output->format),
+           output->width, output->height, output->pts);
+
+    return ff_filter_frame(outlink, output);
+
+fail:
+    clFinish(ctx->command_queue);
+    av_frame_free(&input);
+    av_frame_free(&output);
+    return err;
+}
+
+static av_cold void nlmeans_opencl_uninit(AVFilterContext *avctx)
+{
+    NLMeansOpenCLContext *ctx = avctx->priv;
+    cl_int cle;
+
+    CL_RELEASE_KERNEL(ctx->vert_kernel);
+    CL_RELEASE_KERNEL(ctx->horiz_kernel);
+    CL_RELEASE_KERNEL(ctx->accum_kernel);
+    CL_RELEASE_KERNEL(ctx->average_kernel);
+
+    CL_RELEASE_MEMORY(ctx->integral_img);
+    CL_RELEASE_MEMORY(ctx->weight);
+    CL_RELEASE_MEMORY(ctx->sum);
+    CL_RELEASE_MEMORY(ctx->overflow);
+
+    CL_RELEASE_QUEUE(ctx->command_queue);
+
+    ff_opencl_filter_uninit(avctx);
+}
+
+#define OFFSET(x) offsetof(NLMeansOpenCLContext, x)
+#define FLAGS (AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_VIDEO_PARAM)
+static const AVOption nlmeans_opencl_options[] = {
+    { "s",  "denoising strength", OFFSET(sigma), AV_OPT_TYPE_DOUBLE, { .dbl = 1.0 }, 1.0, 30.0, FLAGS },
+    { "p",  "patch size",                   OFFSET(patch_size),    AV_OPT_TYPE_INT, { .i64 = 2*3+1 }, 0, 99, FLAGS },
+    { "pc", "patch size for chroma planes", OFFSET(patch_size_uv), AV_OPT_TYPE_INT, { .i64 = 0 },     0, 99, FLAGS },
+    { "r",  "research window",                   OFFSET(research_size),    AV_OPT_TYPE_INT, { .i64 = 7*2+1 }, 0, 99, FLAGS },
+    { "rc", "research window for chroma planes", OFFSET(research_size_uv), AV_OPT_TYPE_INT, { .i64 = 0 },     0, 99, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(nlmeans_opencl);
+
+static const AVFilterPad nlmeans_opencl_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = &nlmeans_opencl_filter_frame,
+        .config_props = &ff_opencl_filter_config_input,
+    },
+    { NULL }
+};
+
+static const AVFilterPad nlmeans_opencl_outputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = &ff_opencl_filter_config_output,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_nlmeans_opencl = {
+    .name           = "nlmeans_opencl",
+    .description    = NULL_IF_CONFIG_SMALL("Non-local means denoiser through OpenCL"),
+    .priv_size      = sizeof(NLMeansOpenCLContext),
+    .priv_class     = &nlmeans_opencl_class,
+    .init           = &ff_opencl_filter_init,
+    .uninit         = &nlmeans_opencl_uninit,
+    .query_formats  = &ff_opencl_filter_query_formats,
+    .inputs         = nlmeans_opencl_inputs,
+    .outputs        = nlmeans_opencl_outputs,
+    .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
+};