lavfi: Add OpenCL avgblur filter

Behaves like the existing avgblur filter, except working on OpenCL
hardware frames. Takes exactly the same options.
Signed-off-by: Mark Thompson <sw@jkqxz.net>

configure

@@ -3228,6 +3228,7 @@ aresample_filter_deps="swresample"
 ass_filter_deps="libass"
 atempo_filter_deps="avcodec"
 atempo_filter_select="rdft"
+avgblur_opencl_filter_deps="opencl"
 azmq_filter_deps="libzmq"
 blackframe_filter_deps="gpl"
 boxblur_filter_deps="gpl"

libavfilter/Makefile

@@ -139,6 +139,8 @@ OBJS-$(CONFIG_ALPHAMERGE_FILTER)             += vf_alphamerge.o
 OBJS-$(CONFIG_ASS_FILTER)                    += vf_subtitles.o
 OBJS-$(CONFIG_ATADENOISE_FILTER)             += vf_atadenoise.o
 OBJS-$(CONFIG_AVGBLUR_FILTER)                += vf_avgblur.o
+OBJS-$(CONFIG_AVGBLUR_OPENCL_FILTER)         += vf_avgblur_opencl.o opencl.o \
+                                                opencl/avgblur.o
 OBJS-$(CONFIG_BBOX_FILTER)                   += bbox.o vf_bbox.o
 OBJS-$(CONFIG_BENCH_FILTER)                  += f_bench.o
 OBJS-$(CONFIG_BITPLANENOISE_FILTER)          += vf_bitplanenoise.o

libavfilter/allfilters.c

@@ -149,6 +149,7 @@ static void register_all(void)
     REGISTER_FILTER(ASS,            ass,            vf);
     REGISTER_FILTER(ATADENOISE,     atadenoise,     vf);
     REGISTER_FILTER(AVGBLUR,        avgblur,        vf);
+    REGISTER_FILTER(AVGBLUR_OPENCL, avgblur_opencl, vf);
     REGISTER_FILTER(BBOX,           bbox,           vf);
     REGISTER_FILTER(BENCH,          bench,          vf);
     REGISTER_FILTER(BITPLANENOISE,  bitplanenoise,  vf);

libavfilter/opencl/avgblur.cl

+/*
+ * Copyright (c) 2018 Dylan Fernando
+ *
+ * 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
+ */
+
+
+__kernel void avgblur_horiz(__write_only image2d_t dst,
+                            __read_only  image2d_t src,
+                            int rad)
+{
+    const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
+                               CLK_FILTER_NEAREST);
+    int2 loc = (int2)(get_global_id(0), get_global_id(1));
+    int2 size = (int2)(get_global_size(0), get_global_size(1));
+
+    int count = 0;
+    float4 acc = (float4)(0,0,0,0);
+
+    for (int xx = max(0, loc.x - rad); xx < min(loc.x + rad + 1, size.x); xx++) {
+        count++;
+        acc += read_imagef(src, sampler, (int2)(xx, loc.y));
+    }
+
+    write_imagef(dst, loc, acc / count);
+}
+
+__kernel void avgblur_vert(__write_only image2d_t dst,
+                           __read_only  image2d_t src,
+                           int radv)
+{
+    const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
+                               CLK_FILTER_NEAREST);
+    int2 loc = (int2)(get_global_id(0), get_global_id(1));
+    int2 size = (int2)(get_global_size(0), get_global_size(1));
+
+    int count = 0;
+    float4 acc = (float4)(0,0,0,0);
+
+    for (int yy = max(0, loc.y - radv); yy < min(loc.y + radv + 1, size.y); yy++) {
+        count++;
+        acc += read_imagef(src, sampler, (int2)(loc.x, yy));
+    }
+
+    write_imagef(dst, loc, acc / count);
+}

libavfilter/opencl_source.h

@@ -19,6 +19,7 @@
 #ifndef AVFILTER_OPENCL_SOURCE_H
 #define AVFILTER_OPENCL_SOURCE_H
 
+extern const char *ff_opencl_source_avgblur;
 extern const char *ff_opencl_source_overlay;
 extern const char *ff_opencl_source_unsharp;