From 4d251723c0a157b77fa9d3c84c74507d399f7254 Mon Sep 17 00:00:00 2001
From: Thilo Borgmann <thilo.borgmann@mail.de>
Date: Sat, 19 Mar 2016 16:28:40 +0100
Subject: [PATCH] lavfi: Add coreimage filter for GPU based image filtering on
 OSX.

---
 Changelog                  |   1 +
 MAINTAINERS                |   1 +
 configure                  |   4 +
 doc/filters.texi           | 166 +++++++++
 libavfilter/Makefile       |   2 +
 libavfilter/allfilters.c   |   2 +
 libavfilter/version.h      |   2 +-
 libavfilter/vf_coreimage.m | 688 +++++++++++++++++++++++++++++++++++++
 8 files changed, 865 insertions(+), 1 deletion(-)
 create mode 100644 libavfilter/vf_coreimage.m

diff --git a/Changelog b/Changelog
index d70f6f0bbd..aaf4c96ccc 100644
--- a/Changelog
+++ b/Changelog
@@ -15,6 +15,7 @@ version <next>:
 - VC-2 HQ RTP payload format (draft v1) depacketizer
 - AudioToolbox audio decoders
 - AudioToolbox audio encoders
+- coreimage filter (GPU based image filtering on OSX)
 
 
 version 3.0:
diff --git a/MAINTAINERS b/MAINTAINERS
index 531c21d74c..a993a675a2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -370,6 +370,7 @@ Filters:
   vf_colorbalance.c                     Paul B Mahol
   vf_colorkey.c                         Timo Rothenpieler
   vf_colorlevels.c                      Paul B Mahol
+  vf_coreimage.m                        Thilo Borgmann
   vf_deband.c                           Paul B Mahol
   vf_dejudder.c                         Nicholas Robbins
   vf_delogo.c                           Jean Delvare (CC <jdelvare@suse.com>)
diff --git a/configure b/configure
index 0987bcd666..feb0bc287b 100755
--- a/configure
+++ b/configure
@@ -5287,6 +5287,8 @@ frei0r_filter_extralibs='$ldl'
 frei0r_src_filter_extralibs='$ldl'
 ladspa_filter_extralibs='$ldl'
 nvenc_encoder_extralibs='$ldl'
+coreimage_filter_extralibs="-framework QuartzCore -framework AppKit -framework OpenGL"
+coreimagesrc_filter_extralibs="-framework QuartzCore -framework AppKit -framework OpenGL"
 
 if ! disabled network; then
     check_func getaddrinfo $network_extralibs
@@ -5516,6 +5518,8 @@ enabled avisynth          && { { check_lib2 "windows.h" LoadLibrary; } ||
                                die "ERROR: LoadLibrary/dlopen not found for avisynth"; }
 enabled cuda              && check_lib cuda.h cuInit -lcuda
 enabled chromaprint       && require chromaprint chromaprint.h chromaprint_get_version -lchromaprint
+enabled coreimage_filter  && { check_header_objcc QuartzCore/CoreImage.h || disable coreimage_filter; }
+enabled coreimagesrc_filter && { check_header_objcc QuartzCore/CoreImage.h || disable coreimagesrc_filter; }
 enabled decklink          && { check_header DeckLinkAPI.h || die "ERROR: DeckLinkAPI.h header not found"; }
 enabled frei0r            && { check_header frei0r.h || die "ERROR: frei0r.h header not found"; }
 enabled gmp               && require2 gmp gmp.h mpz_export -lgmp
diff --git a/doc/filters.texi b/doc/filters.texi
index e6ffbed65a..528e0f8012 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -4955,6 +4955,111 @@ convolution="-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -
 Copy the input source unchanged to the output. This is mainly useful for
 testing purposes.
 
+@anchor{coreimage}
+@section coreimage
+Video filtering on GPU using Apple's CoreImage API on OSX.
+
+Hardware acceleration is based on an OpenGL context. Usually, this means it is
+processed by video hardware. However, software-based OpenGL implementations
+exist which means there is no guarantee for hardware processing. It depends on
+the respective OSX.
+
+There are many filters and image generators provided by Apple that come with a
+large variety of options. The filter has to be referenced by its name along
+with its options.
+
+The coreimage filter accepts the following options:
+@table @option
+@item list_filters
+List all available filters and generators along with all their respective
+options as well as possible minimum and maximum values along with the default
+values.
+@example
+list_filters=true
+@end example
+
+@item filter
+Specify all filters by their respective name and options.
+Use @var{list_filters} to determine all valid filter names and options.
+Numerical options are specified by a float value and are automatically clamped
+to their respective value range.  Vector and color options have to be specified
+by a list of space separated float values. Character escaping has to be done.
+A special option name @code{default} is available to use default options for a
+filter.
+
+It is required to specify either @code{default} or at least one of the filter options.
+All omitted options are used with their default values.
+The syntax of the filter string is as follows:
+@example
+filter=<NAME>@@<OPTION>=<VALUE>[@@<OPTION>=<VALUE>][@@...][#<NAME>@@<OPTION>=<VALUE>[@@<OPTION>=<VALUE>][@@...]][#...]
+@end example
+
+@item output_rect
+Specify a rectangle where the output of the filter chain is copied into the
+input image. It is given by a list of space separated float values:
+@example
+output_rect=x\ y\ width\ height
+@end example
+If not given, the output rectangle equals the dimensions of the input image.
+The output rectangle is automatically cropped at the borders of the input
+image. Negative values are valid for each component.
+@example
+output_rect=25\ 25\ 100\ 100
+@end example
+@end table
+
+Several filters can be chained for successive processing without GPU-HOST
+transfers allowing for fast processing of complex filter chains.
+Currently, only filters with zero (generators) or exactly one (filters) input
+image and one output image are supported. Also, transition filters are not yet
+usable as intended.
+
+Some filters generate output images with additional padding depending on the
+respective filter kernel. The padding is automatically removed to ensure the
+filter output has the same size as the input image.
+
+For image generators, the size of the output image is determined by the
+previous output image of the filter chain or the input image of the whole
+filterchain, respectively. The generators do not use the pixel information of
+this image to generate their output. However, the generated output is
+blended onto this image, resulting in partial or complete coverage of the
+output image.
+
+The @ref{coreimagesrc} video source can be used for generating input images
+which are directly fed into the filter chain. By using it, providing input
+images by another video source or an input video is not required.
+
+@subsection Examples
+
+@itemize
+
+@item
+List all filters available:
+@example
+coreimage=list_filters=true
+@end example
+
+@item
+Use the CIBoxBlur filter with default options to blur an image:
+@example
+coreimage=filter=CIBoxBlur@@default
+@end example
+
+@item
+Use a filter chain with CISepiaTone at default values and CIVignetteEffect with
+its center at 100x100 and a radius of 50 pixels:
+@example
+coreimage=filter=CIBoxBlur@@default#CIVignetteEffect@@inputCenter=100\ 100@@inputRadius=50
+@end example
+
+@item
+Use nullsrc and CIQRCodeGenerator to create a QR code for the FFmpeg homepage,
+given as complete and escaped command-line for Apple's standard bash shell:
+@example
+ffmpeg -f lavfi -i nullsrc=s=100x100,coreimage=filter=CIQRCodeGenerator@@inputMessage=https\\\\\://FFmpeg.org/@@inputCorrectionLevel=H -frames:v 1 QRCode.png
+@end example
+@end itemize
+
 @section crop
 
 Crop the input video to given dimensions.
@@ -13798,6 +13903,67 @@ cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
 
 @end itemize
 
+@anchor{coreimagesrc}
+@section coreimagesrc
+Video source generated on GPU using Apple's CoreImage API on OSX.
+
+This video source is a specialized version of the @ref{coreimage} video filter.
+Use a core image generator at the beginning of the applied filterchain to
+generate the content.
+
+The coreimagesrc video source accepts the following options:
+@table @option
+@item list_generators
+List all available generators along with all their respective options as well as
+possible minimum and maximum values along with the default values.
+@example
+list_generators=true
+@end example
+
+@item size, s
+Specify the size of the sourced video. For the syntax of this option, check the
+@ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
+The default value is @code{320x240}.
+
+@item rate, r
+Specify the frame rate of the sourced video, as the number of frames
+generated per second. It has to be a string in the format
+@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
+number or a valid video frame rate abbreviation. The default value is
+"25".
+
+@item sar
+Set the sample aspect ratio of the sourced video.
+
+@item duration, d
+Set the duration of the sourced video. See
+@ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
+for the accepted syntax.
+
+If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
+@end table
+
+Additionally, all options of the @ref{coreimage} video filter are accepted.
+A complete filterchain can be used for further processing of the
+generated input without CPU-HOST transfer. See @ref{coreimage} documentation
+and examples for details.
+
+@subsection Examples
+
+@itemize
+
+@item
+Use CIQRCodeGenerator to create a QR code for the FFmpeg homepage,
+given as complete and escaped command-line for Apple's standard bash shell:
+@example
+ffmpeg -f lavfi -i coreimagesrc=s=100x100:filter=CIQRCodeGenerator@@inputMessage=https\\\\\://FFmpeg.org/@@inputCorrectionLevel=H -frames:v 1 QRCode.png
+@end example
+This example is equivalent to the QRCode example of @ref{coreimage} without the
+need for a nullsrc video source.
+@end itemize
+
+
 @section mandelbrot
 
 Generate a Mandelbrot set fractal, and progressively zoom towards the
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 956a077646..b6e1999d4c 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -133,6 +133,7 @@ OBJS-$(CONFIG_COLORLEVELS_FILTER)            += vf_colorlevels.o
 OBJS-$(CONFIG_COLORMATRIX_FILTER)            += vf_colormatrix.o
 OBJS-$(CONFIG_CONVOLUTION_FILTER)            += vf_convolution.o
 OBJS-$(CONFIG_COPY_FILTER)                   += vf_copy.o
+OBJS-$(CONFIG_COREIMAGE_FILTER)              += vf_coreimage.o
 OBJS-$(CONFIG_COVER_RECT_FILTER)             += vf_cover_rect.o lavfutils.o
 OBJS-$(CONFIG_CROP_FILTER)                   += vf_crop.o
 OBJS-$(CONFIG_CROPDETECT_FILTER)             += vf_cropdetect.o
@@ -282,6 +283,7 @@ OBJS-$(CONFIG_ALLRGB_FILTER)                 += vsrc_testsrc.o
 OBJS-$(CONFIG_ALLYUV_FILTER)                 += vsrc_testsrc.o
 OBJS-$(CONFIG_CELLAUTO_FILTER)               += vsrc_cellauto.o
 OBJS-$(CONFIG_COLOR_FILTER)                  += vsrc_testsrc.o
+OBJS-$(CONFIG_COREIMAGESRC_FILTER)           += vf_coreimage.o
 OBJS-$(CONFIG_FREI0R_SRC_FILTER)             += vf_frei0r.o
 OBJS-$(CONFIG_HALDCLUTSRC_FILTER)            += vsrc_testsrc.o
 OBJS-$(CONFIG_LIFE_FILTER)                   += vsrc_life.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index e5080b5d0a..5c18fd18c4 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -154,6 +154,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(COLORMATRIX,    colormatrix,    vf);
     REGISTER_FILTER(CONVOLUTION,    convolution,    vf);
     REGISTER_FILTER(COPY,           copy,           vf);
+    REGISTER_FILTER(COREIMAGE,      coreimage,      vf);
     REGISTER_FILTER(COVER_RECT,     cover_rect,     vf);
     REGISTER_FILTER(CROP,           crop,           vf);
     REGISTER_FILTER(CROPDETECT,     cropdetect,     vf);
@@ -302,6 +303,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(ALLYUV,         allyuv,         vsrc);
     REGISTER_FILTER(CELLAUTO,       cellauto,       vsrc);
     REGISTER_FILTER(COLOR,          color,          vsrc);
+    REGISTER_FILTER(COREIMAGESRC,   coreimagesrc,   vsrc);
     REGISTER_FILTER(FREI0R,         frei0r_src,     vsrc);
     REGISTER_FILTER(HALDCLUTSRC,    haldclutsrc,    vsrc);
     REGISTER_FILTER(LIFE,           life,           vsrc);
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 80e7c71d82..94c6bdc662 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  39
+#define LIBAVFILTER_VERSION_MINOR  40
 #define LIBAVFILTER_VERSION_MICRO 102
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
diff --git a/libavfilter/vf_coreimage.m b/libavfilter/vf_coreimage.m
new file mode 100644
index 0000000000..0b93049642
--- /dev/null
+++ b/libavfilter/vf_coreimage.m
@@ -0,0 +1,688 @@
+/*
+ * Copyright (c) 2016 Thilo Borgmann
+ *
+ * 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
+ * Video processing based on Apple's CoreImage API
+ */
+
+#import <QuartzCore/CoreImage.h>
+#import <AppKit/AppKit.h>
+
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+#include "libavutil/internal.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+
+typedef struct CoreImageContext {
+    const AVClass   *class;
+
+    int             is_video_source;    ///< filter is used as video source
+
+    int             w, h;               ///< video size
+    AVRational      sar;                ///< sample aspect ratio
+    AVRational      frame_rate;         ///< video frame rate
+    AVRational      time_base;          ///< stream time base
+    int64_t         duration;           ///< duration expressed in microseconds
+    int64_t         pts;                ///< increasing presentation time stamp
+    AVFrame         *picref;            ///< cached reference containing the painted picture
+
+    CFTypeRef       glctx;              ///< OpenGL context
+    CGContextRef    cgctx;              ///< Bitmap context for image copy
+    CFTypeRef       input_image;        ///< Input image container for passing into Core Image API
+    CGColorSpaceRef color_space;        ///< Common color space for input image and cgcontext
+    int             bits_per_component; ///< Shared bpc for input-output operation
+
+    char            *filter_string;     ///< The complete user provided filter definition
+    CFTypeRef       *filters;           ///< CIFilter object for all requested filters
+    int             num_filters;        ///< Amount of filters in *filters
+
+    char            *output_rect;       ///< Rectangle to be filled with filter intput
+    int             list_filters;       ///< Option used to list all available filters including generators
+    int             list_generators;    ///< Option used to list all available generators
+} CoreImageContext;
+
+static int config_output(AVFilterLink *link)
+{
+    CoreImageContext *ctx = link->src->priv;
+
+    link->w                   = ctx->w;
+    link->h                   = ctx->h;
+    link->sample_aspect_ratio = ctx->sar;
+    link->frame_rate          = ctx->frame_rate;
+    link->time_base           = ctx->time_base;
+
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
+    ctx->bits_per_component        = av_get_bits_per_pixel(desc) / desc->nb_components;
+
+    return 0;
+}
+
+/** Determine image properties from input link of filter chain.
+ */
+static int config_input(AVFilterLink *link)
+{
+    CoreImageContext *ctx          = link->dst->priv;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
+    ctx->bits_per_component        = av_get_bits_per_pixel(desc) / desc->nb_components;
+
+    return 0;
+}
+
+/** Print a list of all available filters including options and respective value ranges and defaults.
+ */
+static void list_filters(CoreImageContext *ctx)
+{
+    // querying filters and attributes
+    NSArray *filter_categories = nil;
+
+    if (ctx->list_generators && !ctx->list_filters) {
+        filter_categories = [NSArray arrayWithObjects:kCICategoryGenerator, nil];
+    }
+
+    NSArray *filter_names = [CIFilter filterNamesInCategories:filter_categories];
+    NSEnumerator *filters = [filter_names objectEnumerator];
+
+    NSString *filter_name;
+    while (filter_name = [filters nextObject]) {
+        av_log(ctx, AV_LOG_INFO, "Filter: %s\n", [filter_name UTF8String]);
+        NSString *input;
+
+        CIFilter *filter             = [CIFilter filterWithName:filter_name];
+        NSDictionary *filter_attribs = [filter attributes]; // <nsstring, id>
+        NSArray      *filter_inputs  = [filter inputKeys];  // <nsstring>
+
+        for (input in filter_inputs) {
+            NSDictionary *input_attribs = [filter_attribs valueForKey:input];
+            NSString *input_class       = [input_attribs valueForKey:kCIAttributeClass];
+            if ([input_class isEqualToString:@"NSNumber"]) {
+                NSNumber *value_default = [input_attribs valueForKey:kCIAttributeDefault];
+                NSNumber *value_min     = [input_attribs valueForKey:kCIAttributeSliderMin];
+                NSNumber *value_max     = [input_attribs valueForKey:kCIAttributeSliderMax];
+
+                av_log(ctx, AV_LOG_INFO, "\tOption: %s\t[%s]\t[%s %s][%s]\n",
+                    [input UTF8String],
+                    [input_class UTF8String],
+                    [[value_min stringValue] UTF8String],
+                    [[value_max stringValue] UTF8String],
+                    [[value_default stringValue] UTF8String]);
+            } else {
+                av_log(ctx, AV_LOG_INFO, "\tOption: %s\t[%s]\n",
+                    [input UTF8String],
+                    [input_class UTF8String]);
+            }
+        }
+    }
+}
+
+static int query_formats(AVFilterContext *fctx)
+{
+    static const enum AVPixelFormat inout_fmts_rgb[] = {
+        AV_PIX_FMT_ARGB,
+        AV_PIX_FMT_NONE
+    };
+
+    AVFilterFormats *inout_formats;
+    int ret;
+
+    if (!(inout_formats = ff_make_format_list(inout_fmts_rgb))) {
+        return AVERROR(ENOMEM);
+    }
+
+    if ((ret = ff_formats_ref(inout_formats, &fctx->inputs[0]->out_formats)) < 0 ||
+        (ret = ff_formats_ref(inout_formats, &fctx->outputs[0]->in_formats)) < 0) {
+        return ret;
+    }
+
+    return 0;
+}
+
+static int query_formats_src(AVFilterContext *fctx)
+{
+    static const enum AVPixelFormat inout_fmts_rgb[] = {
+        AV_PIX_FMT_ARGB,
+        AV_PIX_FMT_NONE
+    };
+
+    AVFilterFormats *inout_formats;
+    int ret;
+
+    if (!(inout_formats = ff_make_format_list(inout_fmts_rgb))) {
+        return AVERROR(ENOMEM);
+    }
+
+    if ((ret = ff_formats_ref(inout_formats, &fctx->outputs[0]->in_formats)) < 0) {
+        return ret;
+    }
+
+    return 0;
+}
+
+static int apply_filter(CoreImageContext *ctx, AVFilterLink *link, AVFrame *frame)
+{
+    int i;
+
+    // (re-)initialize input image
+    const CGSize frame_size = {
+        frame->width,
+        frame->height
+    };
+
+    NSData *data = [NSData dataWithBytesNoCopy:frame->data[0]
+                           length:frame->height*frame->linesize[0]
+                           freeWhenDone:NO];
+
+    CIImage *ret = [(__bridge CIImage*)ctx->input_image initWithBitmapData:data
+                                                        bytesPerRow:frame->linesize[0]
+                                                        size:frame_size
+                                                        format:kCIFormatARGB8
+                                                        colorSpace:ctx->color_space]; //kCGColorSpaceGenericRGB
+    if (!ret) {
+        av_log(ctx, AV_LOG_ERROR, "Input image could not be initialized.\n");
+        return AVERROR_EXTERNAL;
+    }
+
+    CIFilter *filter       = NULL;
+    CIImage *filter_input  = (__bridge CIImage*)ctx->input_image;
+    CIImage *filter_output = NULL;
+
+    // successively apply all filters
+    for (i = 0; i < ctx->num_filters; i++) {
+        if (i) {
+            // set filter input to previous filter output
+            filter_input    = [(__bridge CIImage*)ctx->filters[i-1] valueForKey:kCIOutputImageKey];
+            CGRect out_rect = [filter_input extent];
+            if (out_rect.size.width > frame->width || out_rect.size.height > frame->height) {
+                // do not keep padded image regions after filtering
+                out_rect.origin.x    = 0.0f;
+                out_rect.origin.y    = 0.0f;
+                out_rect.size.width  = frame->width;
+                out_rect.size.height = frame->height;
+            }
+            filter_input = [filter_input imageByCroppingToRect:out_rect];
+        }
+
+        filter = (__bridge CIFilter*)ctx->filters[i];
+
+        // do not set input image for the first filter if used as video source
+        if (!ctx->is_video_source || i) {
+            @try {
+                [filter setValue:filter_input forKey:kCIInputImageKey];
+            } @catch (NSException *exception) {
+                if (![[exception name] isEqualToString:NSUndefinedKeyException]) {
+                    av_log(ctx, AV_LOG_ERROR, "An error occurred: %s.", [exception.reason UTF8String]);
+                    return AVERROR_EXTERNAL;
+                } else {
+                    av_log(ctx, AV_LOG_WARNING, "Selected filter does not accept an input image.\n");
+                }
+            }
+        }
+    }
+
+    // get output of last filter
+    filter_output = [filter valueForKey:kCIOutputImageKey];
+
+    if (!filter_output) {
+        av_log(ctx, AV_LOG_ERROR, "Filter output not available.\n");
+        return AVERROR_EXTERNAL;
+    }
+
+    // do not keep padded image regions after filtering
+    CGRect out_rect = [filter_output extent];
+    if (out_rect.size.width > frame->width || out_rect.size.height > frame->height) {
+        av_log(ctx, AV_LOG_DEBUG, "Cropping output image.\n");
+        out_rect.origin.x    = 0.0f;
+        out_rect.origin.y    = 0.0f;
+        out_rect.size.width  = frame->width;
+        out_rect.size.height = frame->height;
+    }
+
+    CGImageRef out = [(__bridge CIContext*)ctx->glctx createCGImage:filter_output
+                                                      fromRect:out_rect];
+
+    if (!out) {
+        av_log(ctx, AV_LOG_ERROR, "Cannot create valid output image.\n");
+    }
+
+    // create bitmap context on the fly for rendering into current frame->data[]
+    if (ctx->cgctx) {
+        CGContextRelease(ctx->cgctx);
+        ctx->cgctx = NULL;
+    }
+    size_t out_width  = CGImageGetWidth(out);
+    size_t out_height = CGImageGetHeight(out);
+
+    if (out_width > frame->width || out_height > frame->height) { // this might result in segfault
+        av_log(ctx, AV_LOG_WARNING, "Output image has unexpected size: %lux%lu (expected: %ix%i). This may crash...\n",
+               out_width, out_height, frame->width, frame->height);
+    }
+    ctx->cgctx = CGBitmapContextCreate(frame->data[0],
+                                       frame->width,
+                                       frame->height,
+                                       ctx->bits_per_component,
+                                       frame->linesize[0],
+                                       ctx->color_space,
+                                       (uint32_t)kCGImageAlphaPremultipliedFirst); // ARGB
+    if (!ctx->cgctx) {
+        av_log(ctx, AV_LOG_ERROR, "CGBitmap context cannot be created.\n");
+        return AVERROR_EXTERNAL;
+    }
+
+    // copy ("draw") the output image into the frame data
+    CGRect rect = {{0,0},{frame->width, frame->height}};
+    if (ctx->output_rect) {
+        @try {
+            NSString *tmp_string = [NSString stringWithUTF8String:ctx->output_rect];
+            NSRect tmp           = NSRectFromString(tmp_string);
+            rect                 = NSRectToCGRect(tmp);
+        } @catch (NSException *exception) {
+            av_log(ctx, AV_LOG_ERROR, "An error occurred: %s.", [exception.reason UTF8String]);
+            return AVERROR_EXTERNAL;
+        }
+        if (rect.size.width == 0.0f) {
+            av_log(ctx, AV_LOG_WARNING, "Width of output rect is zero.\n");
+        }
+        if (rect.size.height == 0.0f) {
+            av_log(ctx, AV_LOG_WARNING, "Height of output rect is zero.\n");
+        }
+    }
+
+    CGContextDrawImage(ctx->cgctx, rect, out);
+
+    return ff_filter_frame(link, frame);
+}
+
+/** Apply all valid filters successively to the input image.
+ *  The final output image is copied from the GPU by "drawing" using a bitmap context.
+ */
+static int filter_frame(AVFilterLink *link, AVFrame *frame)
+{
+    return apply_filter(link->dst->priv, link->dst->outputs[0], frame);
+}
+
+static int request_frame(AVFilterLink *link)
+{
+    CoreImageContext *ctx = link->src->priv;
+    AVFrame *frame;
+
+    if (ctx->duration >= 0 &&
+        av_rescale_q(ctx->pts, ctx->time_base, AV_TIME_BASE_Q) >= ctx->duration) {
+        return AVERROR_EOF;
+    }
+
+    if (!ctx->picref) {
+        ctx->picref = ff_get_video_buffer(link, ctx->w, ctx->h);
+        if (!ctx->picref) {
+            return AVERROR(ENOMEM);
+        }
+    }
+
+    frame = av_frame_clone(ctx->picref);
+    if (!frame) {
+        return AVERROR(ENOMEM);
+    }
+
+    frame->pts                 = ctx->pts;
+    frame->key_frame           = 1;
+    frame->interlaced_frame    = 0;
+    frame->pict_type           = AV_PICTURE_TYPE_I;
+    frame->sample_aspect_ratio = ctx->sar;
+
+    ctx->pts++;
+
+    return apply_filter(ctx, link, frame);
+}
+
+/** Set an option of the given filter to the provided key-value pair.
+ */
+static void set_option(CoreImageContext *ctx, CIFilter *filter, const char *key, const char *value)
+{
+        NSString *input_key = [NSString stringWithUTF8String:key];
+        NSString *input_val = [NSString stringWithUTF8String:value];
+
+        NSDictionary *filter_attribs = [filter attributes]; // <nsstring, id>
+        NSDictionary *input_attribs  = [filter_attribs valueForKey:input_key];
+
+        NSString *input_class = [input_attribs valueForKey:kCIAttributeClass];
+        NSString *input_type  = [input_attribs valueForKey:kCIAttributeType];
+
+        if (!input_attribs) {
+            av_log(ctx, AV_LOG_WARNING, "Skipping unknown option: \"%s\".\n",
+                   [input_key UTF8String]); // [[filter name] UTF8String]) not currently defined...
+            return;
+        }
+
+        av_log(ctx, AV_LOG_DEBUG, "key: %s, val: %s, #attribs: %lu, class: %s, type: %s\n",
+               [input_key UTF8String],
+               [input_val UTF8String],
+               input_attribs ? (unsigned long)[input_attribs count] : -1,
+               [input_class UTF8String],
+               [input_type UTF8String]);
+
+        if ([input_class isEqualToString:@"NSNumber"]) {
+            float input          = input_val.floatValue;
+            NSNumber *max_value  = [input_attribs valueForKey:kCIAttributeSliderMax];
+            NSNumber *min_value  = [input_attribs valueForKey:kCIAttributeSliderMin];
+            NSNumber *used_value = nil;
+
+#define CLAMP_WARNING do {     \
+av_log(ctx, AV_LOG_WARNING, "Value of \"%f\" for option \"%s\" is out of range [%f %f], clamping to \"%f\".\n", \
+       input,                  \
+       [input_key UTF8String], \
+       min_value.floatValue,   \
+       max_value.floatValue,   \
+       used_value.floatValue); \
+} while(0)
+            if (input > max_value.floatValue) {
+                used_value = max_value;
+                CLAMP_WARNING;
+            } else if (input < min_value.floatValue) {
+                used_value = min_value;
+                CLAMP_WARNING;
+            } else {
+                used_value = [NSNumber numberWithFloat:input];
+            }
+
+            [filter setValue:used_value forKey:input_key];
+        } else if ([input_class isEqualToString:@"CIVector"]) {
+            CIVector *input = [CIVector vectorWithString:input_val];
+
+            if (!input) {
+                av_log(ctx, AV_LOG_WARNING, "Skipping invalid CIVctor description: \"%s\".\n",
+                       [input_val UTF8String]);
+                return;
+            }
+
+            [filter setValue:input forKey:input_key];
+        } else if ([input_class isEqualToString:@"CIColor"]) {
+            CIColor *input = [CIColor colorWithString:input_val];
+
+            if (!input) {
+                av_log(ctx, AV_LOG_WARNING, "Skipping invalid CIColor description: \"%s\".\n",
+                       [input_val UTF8String]);
+                return;
+            }
+
+            [filter setValue:input forKey:input_key];
+        } else if ([input_class isEqualToString:@"NSString"]) { // set display name as string with latin1 encoding
+            [filter setValue:input_val forKey:input_key];
+        } else if ([input_class isEqualToString:@"NSData"]) { // set display name as string with latin1 encoding
+            NSData *input = [NSData dataWithBytes:(const void*)[input_val cStringUsingEncoding:NSISOLatin1StringEncoding]
+                                    length:[input_val lengthOfBytesUsingEncoding:NSISOLatin1StringEncoding]];
+
+            if (!input) {
+                av_log(ctx, AV_LOG_WARNING, "Skipping invalid NSData description: \"%s\".\n",
+                       [input_val UTF8String]);
+                return;
+            }
+
+            [filter setValue:input forKey:input_key];
+        } else {
+            av_log(ctx, AV_LOG_WARNING, "Skipping unsupported option class: \"%s\".\n",
+                   [input_class UTF8String]);
+            avpriv_report_missing_feature(ctx, "Handling of some option classes");
+            return;
+        }
+}
+
+/** Create a filter object by a given name and set all options to defaults.
+ *  Overwrite any option given by the user to the provided value in filter_options.
+ */
+static CIFilter* create_filter(CoreImageContext *ctx, const char *filter_name, AVDictionary *filter_options)
+{
+    // create filter object
+    CIFilter *filter = [CIFilter filterWithName:[NSString stringWithUTF8String:filter_name]];
+
+    // set default options
+    [filter setDefaults];
+
+    // set user options
+    if (filter_options) {
+        AVDictionaryEntry *o = NULL;
+        while ((o = av_dict_get(filter_options, "", o, AV_DICT_IGNORE_SUFFIX))) {
+            set_option(ctx, filter, o->key, o->value);
+        }
+    }
+
+    return filter;
+}
+
+static av_cold int init(AVFilterContext *fctx)
+{
+    CoreImageContext *ctx     = fctx->priv;
+    AVDictionary *filter_dict = NULL;
+    AVDictionaryEntry *f      = NULL;
+    AVDictionaryEntry *o      = NULL;
+    int ret;
+    int i;
+
+    if (ctx->list_filters || ctx->list_generators) {
+        list_filters(ctx);
+        return AVERROR_EXIT;
+    }
+
+    if (ctx->filter_string) {
+        // parse filter string (filter=name@opt=val@opt2=val2#name2@opt3=val3) for filters separated by #
+        av_log(ctx, AV_LOG_DEBUG, "Filter_string: %s\n", ctx->filter_string);
+        ret = av_dict_parse_string(&filter_dict, ctx->filter_string, "@", "#", AV_DICT_MULTIKEY); // parse filter_name:all_filter_options
+        if (ret) {
+            av_log(ctx, AV_LOG_ERROR, "Parsing of filters failed.\n");
+            return AVERROR(EIO);
+        }
+        ctx->num_filters = av_dict_count(filter_dict);
+        av_log(ctx, AV_LOG_DEBUG, "Filter count: %i\n", ctx->num_filters);
+
+        // allocate CIFilter array
+        ctx->filters = av_mallocz_array(ctx->num_filters, sizeof(CIFilter*));
+        if (!ctx->filters) {
+            av_log(ctx, AV_LOG_ERROR, "Could not allocate filter array.\n");
+            return AVERROR(ENOMEM);
+        }
+
+        // parse filters for option key-value pairs (opt=val@opt2=val2) separated by @
+        i = 0;
+        while ((f = av_dict_get(filter_dict, "", f, AV_DICT_IGNORE_SUFFIX))) {
+            AVDictionary *filter_options = NULL;
+
+            if (strncmp(f->value, "default", 7)) { // not default
+                ret = av_dict_parse_string(&filter_options, f->value, "=", "@", 0); // parse option_name:option_value
+                if (ret) {
+                    av_log(ctx, AV_LOG_ERROR, "Parsing of filter options for \"%s\" failed.\n", f->key);
+                    return AVERROR(EIO);
+                }
+            }
+
+            if (av_log_get_level() >= AV_LOG_DEBUG) {
+                av_log(ctx, AV_LOG_DEBUG, "Creating filter %i: \"%s\":\n", i, f->key);
+                if (!filter_options) {
+                    av_log(ctx, AV_LOG_DEBUG, "\tusing default options\n");
+                } else {
+                    while ((o = av_dict_get(filter_options, "", o, AV_DICT_IGNORE_SUFFIX))) {
+                        av_log(ctx, AV_LOG_DEBUG, "\t%s: %s\n", o->key, o->value);
+                    }
+                }
+            }
+
+            ctx->filters[i] = CFBridgingRetain(create_filter(ctx, f->key, filter_options));
+            if (!ctx->filters[i]) {
+                av_log(ctx, AV_LOG_ERROR, "Could not create filter \"%s\".\n", f->key);
+                return AVERROR(EINVAL);
+            }
+
+            i++;
+        }
+    } else {
+        av_log(ctx, AV_LOG_ERROR, "No filters specified.\n");
+        return AVERROR(EINVAL);
+    }
+
+    // create GPU context on OSX
+    const NSOpenGLPixelFormatAttribute attr[] = {
+        NSOpenGLPFAAccelerated,
+        NSOpenGLPFANoRecovery,
+        NSOpenGLPFAColorSize, 32,
+        0
+    };
+
+    NSOpenGLPixelFormat *pixel_format = [[NSOpenGLPixelFormat alloc] initWithAttributes:(void *)&attr];
+    ctx->color_space                  = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
+    ctx->glctx                        = CFBridgingRetain([CIContext contextWithCGLContext:CGLGetCurrentContext()
+                                                         pixelFormat:[pixel_format CGLPixelFormatObj]
+                                                         colorSpace:ctx->color_space
+                                                         options:nil]);
+
+    if (!ctx->glctx) {
+        av_log(ctx, AV_LOG_ERROR, "CIContext not created.\n");
+        return AVERROR_EXTERNAL;
+    }
+
+    // Creating an empty input image as input container for the context
+    ctx->input_image = CFBridgingRetain([CIImage emptyImage]);
+
+    return 0;
+}
+
+static av_cold int init_src(AVFilterContext *fctx)
+{
+    CoreImageContext *ctx = fctx->priv;
+
+    ctx->is_video_source = 1;
+    ctx->time_base       = av_inv_q(ctx->frame_rate);
+    ctx->pts             = 0;
+
+    return init(fctx);
+}
+
+static av_cold void uninit(AVFilterContext *fctx)
+{
+#define SafeCFRelease(ptr) do { \
+    if (ptr) {                  \
+        CFRelease(ptr);         \
+        ptr = NULL;             \
+    }                           \
+} while (0)
+
+    CoreImageContext *ctx = fctx->priv;
+
+    SafeCFRelease(ctx->glctx);
+    SafeCFRelease(ctx->cgctx);
+    SafeCFRelease(ctx->color_space);
+    SafeCFRelease(ctx->input_image);
+
+    if (ctx->filters) {
+        for (int i = 0; i < ctx->num_filters; i++) {
+            SafeCFRelease(ctx->filters[i]);
+        }
+        av_freep(&ctx->filters);
+    }
+
+    av_frame_free(&ctx->picref);
+}
+
+static const AVFilterPad vf_coreimage_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+        .config_props = config_input,
+    },
+    { NULL }
+};
+
+static const AVFilterPad vf_coreimage_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+    },
+    { NULL }
+};
+
+static const AVFilterPad vsrc_coreimagesrc_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .request_frame = request_frame,
+        .config_props  = config_output,
+    },
+    { NULL }
+};
+
+#define OFFSET(x) offsetof(CoreImageContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+#define GENERATOR_OPTIONS                                                                                                               \
+    {"size",     "set video size",                OFFSET(w),          AV_OPT_TYPE_IMAGE_SIZE, {.str = "320x240"}, 0, 0,         FLAGS}, \
+    {"s",        "set video size",                OFFSET(w),          AV_OPT_TYPE_IMAGE_SIZE, {.str = "320x240"}, 0, 0,         FLAGS}, \
+    {"rate",     "set video rate",                OFFSET(frame_rate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"},      0, 0,         FLAGS}, \
+    {"r",        "set video rate",                OFFSET(frame_rate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"},      0, 0,         FLAGS}, \
+    {"duration", "set video duration",            OFFSET(duration),   AV_OPT_TYPE_DURATION,   {.i64 = -1},       -1, INT64_MAX, FLAGS}, \
+    {"d",        "set video duration",            OFFSET(duration),   AV_OPT_TYPE_DURATION,   {.i64 = -1},       -1, INT64_MAX, FLAGS}, \
+    {"sar",      "set video sample aspect ratio", OFFSET(sar),        AV_OPT_TYPE_RATIONAL,   {.dbl = 1},         0, INT_MAX,   FLAGS},
+
+#define FILTER_OPTIONS                                                                                                                           \
+    {"list_filters",    "list available filters",                OFFSET(list_filters),    AV_OPT_TYPE_BOOL,   {.i64 = 0}, 0, 1, .flags = FLAGS}, \
+    {"list_generators", "list available generators",             OFFSET(list_generators), AV_OPT_TYPE_BOOL,   {.i64 = 0}, 0, 1, .flags = FLAGS}, \
+    {"filter",          "names and options of filters to apply", OFFSET(filter_string),   AV_OPT_TYPE_STRING, {.str = NULL},    .flags = FLAGS}, \
+    {"output_rect",     "output rectangle within output image",  OFFSET(output_rect),     AV_OPT_TYPE_STRING, {.str = NULL},    .flags = FLAGS},
+
+
+// definitions for coreimage video filter
+static const AVOption coreimage_options[] = {
+    FILTER_OPTIONS
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(coreimage);
+
+AVFilter ff_vf_coreimage = {
+    .name          = "coreimage",
+    .description   = NULL_IF_CONFIG_SMALL("Video filtering using CoreImage API."),
+    .init          = init,
+    .uninit        = uninit,
+    .priv_size     = sizeof(CoreImageContext),
+    .priv_class    = &coreimage_class,
+    .inputs        = vf_coreimage_inputs,
+    .outputs       = vf_coreimage_outputs,
+    .query_formats = query_formats,
+};
+
+// definitions for coreimagesrc video source
+static const AVOption coreimagesrc_options[] = {
+    GENERATOR_OPTIONS
+    FILTER_OPTIONS
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(coreimagesrc);
+
+AVFilter ff_vsrc_coreimagesrc = {
+    .name          = "coreimagesrc",
+    .description   = NULL_IF_CONFIG_SMALL("Video source using image generators of CoreImage API."),
+    .init          = init_src,
+    .uninit        = uninit,
+    .priv_size     = sizeof(CoreImageContext),
+    .priv_class    = &coreimagesrc_class,
+    .inputs        = NULL,
+    .outputs       = vsrc_coreimagesrc_outputs,
+    .query_formats = query_formats_src,
+};