[FFmpeg-devel] [PATCH] lavfi: add geq filter.

Clément Bœsch ubitux at gmail.com
Sat Nov 10 22:34:59 CET 2012


On Sat, Nov 10, 2012 at 06:16:38PM +0100, Stefano Sabatini wrote:
[...]
> > > Also, what happens if the (x,y) value is not contained in the image?
> > > 
> > 
> > Added a note about the clipping (and BTW, I had to change the original
> > code to clip to w-2 and h-2 instead of w-1 and h-1 to avoid overreads).
> 
> Another idea would be to wrap around the values, but that would
> involve a modulo operation so should be optional.
> 

I'd like to keep the first commit a port without any addition, and with
minimal changes if you don't mind…

[...]
> > diff --git a/doc/filters.texi b/doc/filters.texi
> > index eaf0f42..e77ec1d 100644
> > --- a/doc/filters.texi
> > +++ b/doc/filters.texi
> > @@ -2364,6 +2364,76 @@ frei0r=perspective:0.2/0.2:0.8/0.2
> >  For more information see:
> >  @url{http://frei0r.dyne.org}
> >  
> > + at section geq
> > +
> > +The filter takes one, two or three equations as parameter, separated by ':'.
> > +The first equation is mandatory and applies to the luma plane. The two
> > +following are respectively for chroma blue and chroma red planes.
> > +
> > +The filter syntax allows named parameters:
> > +
> > + at table @option
> > + at item lum_expr
> > +the luminance expression
> > + at item cb_expr
> > +the chrominance blue expression
> > + at item cr_expr
> > +the chrominance red expression
> > + at end table
> > +
> 
> > +If one of the chrominance expression isn't defined, it fall backs on the other
> > +one. If none of them are specified, they will evaluate the luminance
> > +expression.
> 
> Nit: maybe just mention the named options, and suggest the alternative
> shorthand, this way it is easier to update the docs in case of
> additions.
> 

I think users will prefer the shorthand syntax most of the time in this
filter, especially given that this is the syntax MPlayer/MEncoder power
users have been using for years.

> Nit++: isn't => is not
> 

Changed, and s/fall backs/falls back/.

> > +
> > +The expressions can use the following variables and functions:
> > +
> 
> > + at table @option
> > + at item X, Y
> > +The coordinates of the current sample
> > +
> > + at item W, H
> > +The width and height of the image
> > +
> > + at item SW, SH
> > +Width and height scale depending on the currently filtered plane, e.g. 1,1 and
> > +0.5,0.5 for YUV 4:2:0.
> 
> nit++: inconsistent final dot
> 

Added '.'

> Also "width and height scale" is not very clear/explicit at all. I'd
> suggest something like:
> 
> Width and height scale depending on the currently filtered plane. It
> is the ratio between the corresponding luma plane number of pixels and
> the current plane ones. E.g. for YUV4:2:0 the values are 1,1 for the luma
> plane, and 0.5,0.5 for chroma planes.
> 

You're my savior, thanks, description changed :)

> ...
> 
> I also wonder how are they useful.
> 

Sorry, I've not used geq enough to answer that. Maybe Michael can comment.

> > +
> > + at item p(x, y)
> > +Return the value of the pixel at location (@var{x}, at var{y}) of the current
> > +plane.
> > +
> > + at item lum(x, y)
> > +Return the value of the pixel at location (@var{x}, at var{y}) of the luminance
> > +plane.
> > +
> > + at item cb(x, y)
> > +Return the value of the pixel at location (@var{x}, at var{y}) of the
> > +blue-difference chroma plane.
> > +
> > + at item cr(x, y)
> > +Return the value of the pixel at location (@var{x}, at var{y}) of the
> > +red-difference chroma plane.
> > + at end table
> > +
> > +For functions, if @var{x} and @var{y} are outside the area, the value will be
> > +automatically clipped to the closer edge.
> > +
> > +Some examples follow:
> > +
> > + at itemize
> > + at item
> > +Flip the image horizontally:
> > + at example
> > +geq=p(W-X\,Y)
> > + at end example
> > +
> 
> > + at item
> > +Fancy enigmatic moving light:
> 
> Nit++: Create/Generate fancy...
> 

Generate, I choose you.

> > + at example
> > +color=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128
> > + at end example
> > + at end itemize
> > +
> >  @section gradfun
> >  
> >  Fix the banding artifacts that are sometimes introduced into nearly flat
> > diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> > index 0ab0633..dfd5200 100644
> > --- a/libavfilter/Makefile
> > +++ b/libavfilter/Makefile
> > @@ -105,6 +105,7 @@ OBJS-$(CONFIG_FORMAT_FILTER)                 += vf_format.o
> >  OBJS-$(CONFIG_FRAMESTEP_FILTER)              += vf_framestep.o
> >  OBJS-$(CONFIG_FPS_FILTER)                    += vf_fps.o
> >  OBJS-$(CONFIG_FREI0R_FILTER)                 += vf_frei0r.o
> > +OBJS-$(CONFIG_GEQ_FILTER)                    += vf_geq.o
> >  OBJS-$(CONFIG_GRADFUN_FILTER)                += vf_gradfun.o
> >  OBJS-$(CONFIG_HFLIP_FILTER)                  += vf_hflip.o
> >  OBJS-$(CONFIG_HQDN3D_FILTER)                 += vf_hqdn3d.o
> > diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> > index fef40e9..88e8d68 100644
> > --- a/libavfilter/allfilters.c
> > +++ b/libavfilter/allfilters.c
> > @@ -97,6 +97,7 @@ void avfilter_register_all(void)
> >      REGISTER_FILTER (FPS,         fps,         vf);
> >      REGISTER_FILTER (FRAMESTEP,   framestep,   vf);
> >      REGISTER_FILTER (FREI0R,      frei0r,      vf);
> > +    REGISTER_FILTER (GEQ,         geq,         vf);
> >      REGISTER_FILTER (GRADFUN,     gradfun,     vf);
> >      REGISTER_FILTER (HFLIP,       hflip,       vf);
> >      REGISTER_FILTER (HQDN3D,      hqdn3d,      vf);
> > diff --git a/libavfilter/vf_geq.c b/libavfilter/vf_geq.c
> > new file mode 100644
> > index 0000000..e0d7716
> > --- /dev/null
> > +++ b/libavfilter/vf_geq.c
> > @@ -0,0 +1,237 @@
> > +/*
> > + * Copyright (C) 2006 Michael Niedermayer <michaelni at gmx.at>
> > + * Copyright (C) 2012 Clément Bœsch <ubitux at gmail.com>
> > + *
> > + * This file is part of MPlayer.
> 
> s/MPlayer/FFmpeg, here and below.
> 

Oups, fixed.

[...]
> > +static int geq_end_frame(AVFilterLink *inlink)
> > +{
> > +    int ret, plane;
> > +    GEQContext *geq = inlink->dst->priv;
> > +    AVFilterLink *outlink = inlink->dst->outputs[0];
> > +    AVFilterBufferRef *outpicref = outlink->out_buf;
> > +    double values[VAR_VARS_NB] = {
> > +        [VAR_N] = geq->framenum++,
> > +    };
> > +
> > +    geq->picref = inlink->cur_buf;
> > +
> > +    for (plane = 0; plane < 3; plane++) {
> > +        int x, y;
> > +        uint8_t *dst = outpicref->data[plane];
> > +        const int linesize = outpicref->linesize[plane];
> > +        const int w = inlink->w >> (plane ? geq->hsub : 0);
> > +        const int h = inlink->h >> (plane ? geq->vsub : 0);
> > +
> > +        values[VAR_W]  = w;
> > +        values[VAR_H]  = h;
> > +        values[VAR_SW] = w / (double)inlink->w;
> > +        values[VAR_SH] = h / (double)inlink->h;
> > +
> > +        for (y = 0; y < h; y++) {
> > +            values[VAR_Y] = y;
> > +            for (x = 0; x < w; x++) {
> > +                values[VAR_X] = x;
> > +                dst[x] = av_expr_eval(geq->e[plane], values, geq);
> 
> Unrelated, but a clipping mechanism (like in lut*) may be useful,
> maybe a warning in case of NaN result.
> 

It's unlikely, but some evil geq filters out there might be exploiting
this, so I'd better not change it in the first version.

> > +            }
> > +            dst += linesize;
> > +        }
> > +    }
> > +
> > +    if ((ret = ff_draw_slice(outlink, 0, outlink->h, 1)) < 0 ||
> > +        (ret = ff_end_frame(outlink)) < 0)
> > +        return ret;
> > +    return 0;
> > +}
> > +
> > +static av_cold void geq_uninit(AVFilterContext *ctx)
> > +{
> > +    int i;
> > +    GEQContext *geq = ctx->priv;
> > +
> > +    for (i = 0; i < FF_ARRAY_ELEMS(geq->e); i++)
> > +        av_expr_free(geq->e[i]);
> 
> av_opt_free()? I think it could be useful to keep the original
> expressions in the context, for debugging reasons.
> 

I don't mind, av_opt_free() moved from init to uninit function.

> > +}
> > +
> > +static int null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir) { return 0; }
> > +
> > +static const AVFilterPad geq_inputs[] = {
> > +    {
> > +        .name         = "default",
> > +        .type         = AVMEDIA_TYPE_VIDEO,
> > +        .draw_slice   = null_draw_slice,
> > +        .config_props = geq_config_props,
> > +        .end_frame    = geq_end_frame,
> > +        .min_perms    = AV_PERM_READ,
> > +    },
> > +    { NULL }
> > +};
> > +
> > +static const AVFilterPad geq_outputs[] = {
> > +    {
> > +        .name = "default",
> > +        .type = AVMEDIA_TYPE_VIDEO,
> > +    },
> > +    { NULL }
> > +};
> > +
> > +AVFilter avfilter_vf_geq = {
> > +    .name          = "geq",
> > +    .description   = NULL_IF_CONFIG_SMALL("Apply generic equation to each pixel."),
> > +    .priv_size     = sizeof(GEQContext),
> > +    .init          = geq_init,
> > +    .uninit        = geq_uninit,
> > +    .query_formats = geq_query_formats,
> > +    .inputs        = geq_inputs,
> > +    .outputs       = geq_outputs,
> > +    .priv_class    = &geq_class,
> > +};
> 
> LGTM otherwise.

I'll push this tomorrow, thanks for the review

-- 
Clément B.
-------------- next part --------------
From f19aa807878841cdcdef10615c03ef532fe56a50 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= <ubitux at gmail.com>
Date: Mon, 14 May 2012 19:03:19 +0200
Subject: [PATCH] lavfi: add geq filter.

TODO: bump minor
---
 Changelog                |   1 +
 LICENSE                  |   1 +
 configure                |   1 +
 doc/filters.texi         |  72 ++++++++++++++
 libavfilter/Makefile     |   1 +
 libavfilter/allfilters.c |   1 +
 libavfilter/vf_geq.c     | 237 +++++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 314 insertions(+)
 create mode 100644 libavfilter/vf_geq.c

diff --git a/Changelog b/Changelog
index 19fda04..9ef12b8 100644
--- a/Changelog
+++ b/Changelog
@@ -22,6 +22,7 @@ version <next>:
 - metadata (info chunk) support in CAF muxer
 - field filter ported from libmpcodecs
 - AVR demuxer
+- geq filter ported from libmpcodecs
 
 
 version 1.0:
diff --git a/LICENSE b/LICENSE
index f38fc16..a1204f4 100644
--- a/LICENSE
+++ b/LICENSE
@@ -30,6 +30,7 @@ Specifically, the GPL parts of FFmpeg are
     - vf_cropdetect.c
     - vf_decimate.c
     - vf_delogo.c
+    - vf_geq.c
     - vf_hqdn3d.c
     - vf_hue.c
     - vf_mp.c
diff --git a/configure b/configure
index ae11f5d..5802cb9 100755
--- a/configure
+++ b/configure
@@ -1939,6 +1939,7 @@ frei0r_filter_deps="frei0r dlopen"
 frei0r_filter_extralibs='$ldl'
 frei0r_src_filter_deps="frei0r dlopen"
 frei0r_src_filter_extralibs='$ldl'
+geq_filter_deps="gpl"
 hqdn3d_filter_deps="gpl"
 hue_filter_deps="gpl"
 movie_filter_deps="avcodec avformat"
diff --git a/doc/filters.texi b/doc/filters.texi
index eaf0f42..5e34ad3 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2364,6 +2364,78 @@ frei0r=perspective:0.2/0.2:0.8/0.2
 For more information see:
 @url{http://frei0r.dyne.org}
 
+ at section geq
+
+The filter takes one, two or three equations as parameter, separated by ':'.
+The first equation is mandatory and applies to the luma plane. The two
+following are respectively for chroma blue and chroma red planes.
+
+The filter syntax allows named parameters:
+
+ at table @option
+ at item lum_expr
+the luminance expression
+ at item cb_expr
+the chrominance blue expression
+ at item cr_expr
+the chrominance red expression
+ at end table
+
+If one of the chrominance expression is not defined, it falls back on the other
+one. If none of them are specified, they will evaluate the luminance
+expression.
+
+The expressions can use the following variables and functions:
+
+ at table @option
+ at item X, Y
+The coordinates of the current sample.
+
+ at item W, H
+The width and height of the image.
+
+ at item SW, SH
+Width and height scale depending on the currently filtered plane. It is the
+ratio between the corresponding luma plane number of pixels and the current
+plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
+ at code{0.5,0.5} for chroma planes.
+
+ at item p(x, y)
+Return the value of the pixel at location (@var{x}, at var{y}) of the current
+plane.
+
+ at item lum(x, y)
+Return the value of the pixel at location (@var{x}, at var{y}) of the luminance
+plane.
+
+ at item cb(x, y)
+Return the value of the pixel at location (@var{x}, at var{y}) of the
+blue-difference chroma plane.
+
+ at item cr(x, y)
+Return the value of the pixel at location (@var{x}, at var{y}) of the
+red-difference chroma plane.
+ at end table
+
+For functions, if @var{x} and @var{y} are outside the area, the value will be
+automatically clipped to the closer edge.
+
+Some examples follow:
+
+ at itemize
+ at item
+Flip the image horizontally:
+ at example
+geq=p(W-X\,Y)
+ at end example
+
+ at item
+Generate a fancy enigmatic moving light:
+ at example
+color=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128
+ at end example
+ at end itemize
+
 @section gradfun
 
 Fix the banding artifacts that are sometimes introduced into nearly flat
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 0ab0633..dfd5200 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -105,6 +105,7 @@ OBJS-$(CONFIG_FORMAT_FILTER)                 += vf_format.o
 OBJS-$(CONFIG_FRAMESTEP_FILTER)              += vf_framestep.o
 OBJS-$(CONFIG_FPS_FILTER)                    += vf_fps.o
 OBJS-$(CONFIG_FREI0R_FILTER)                 += vf_frei0r.o
+OBJS-$(CONFIG_GEQ_FILTER)                    += vf_geq.o
 OBJS-$(CONFIG_GRADFUN_FILTER)                += vf_gradfun.o
 OBJS-$(CONFIG_HFLIP_FILTER)                  += vf_hflip.o
 OBJS-$(CONFIG_HQDN3D_FILTER)                 += vf_hqdn3d.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index fef40e9..88e8d68 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -97,6 +97,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (FPS,         fps,         vf);
     REGISTER_FILTER (FRAMESTEP,   framestep,   vf);
     REGISTER_FILTER (FREI0R,      frei0r,      vf);
+    REGISTER_FILTER (GEQ,         geq,         vf);
     REGISTER_FILTER (GRADFUN,     gradfun,     vf);
     REGISTER_FILTER (HFLIP,       hflip,       vf);
     REGISTER_FILTER (HQDN3D,      hqdn3d,      vf);
diff --git a/libavfilter/vf_geq.c b/libavfilter/vf_geq.c
new file mode 100644
index 0000000..548e3c3
--- /dev/null
+++ b/libavfilter/vf_geq.c
@@ -0,0 +1,237 @@
+/*
+ * Copyright (C) 2006 Michael Niedermayer <michaelni at gmx.at>
+ * Copyright (C) 2012 Clément Bœsch <ubitux at gmail.com>
+ *
+ * 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
+ * Generic equation change filter
+ * Originally written by Michael Niedermayer for the MPlayer project, and
+ * ported by Clément Bœsch for FFmpeg.
+ */
+
+#include "libavutil/avstring.h"
+#include "libavutil/eval.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "internal.h"
+
+typedef struct {
+    const AVClass *class;
+    AVExpr *e[3];               ///< expressions for each plane
+    char *expr_str[3];          ///< expression strings for each plane
+    int framenum;               ///< frame counter
+    AVFilterBufferRef *picref;  ///< current input buffer
+    int hsub, vsub;             ///< chroma subsampling
+} GEQContext;
+
+#define OFFSET(x) offsetof(GEQContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption geq_options[] = {
+    { "lum_expr",   "set luminance expression",   OFFSET(expr_str),                   AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
+    { "cb_expr",    "set chroma blue expression", OFFSET(expr_str) +   sizeof(char*), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
+    { "cr_expr",    "set chroma red expression",  OFFSET(expr_str) + 2*sizeof(char*), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
+    {NULL},
+};
+
+AVFILTER_DEFINE_CLASS(geq);
+
+static inline double getpix(void *priv, double x, double y, int plane)
+{
+    int xi, yi;
+    GEQContext *geq = priv;
+    AVFilterBufferRef *picref = geq->picref;
+    const uint8_t *src = picref->data[plane];
+    const int linesize = picref->linesize[plane];
+    const int w = picref->video->w >> (plane ? geq->hsub : 0);
+    const int h = picref->video->h >> (plane ? geq->vsub : 0);
+
+    xi = x = av_clipf(x, 0, w - 2);
+    yi = y = av_clipf(y, 0, h - 2);
+
+    x -= xi;
+    y -= yi;
+
+    return (1-y)*((1-x)*src[xi +  yi    * linesize] + x*src[xi + 1 +  yi    * linesize])
+          +   y *((1-x)*src[xi + (yi+1) * linesize] + x*src[xi + 1 + (yi+1) * linesize]);
+}
+
+//TODO: cubic interpolate
+//TODO: keep the last few frames
+static double lum(void *priv, double x, double y) { return getpix(priv, x, y, 0); }
+static double  cb(void *priv, double x, double y) { return getpix(priv, x, y, 1); }
+static double  cr(void *priv, double x, double y) { return getpix(priv, x, y, 2); }
+
+static const char *const var_names[] = {   "X",   "Y",   "W",   "H",   "N",   "SW",   "SH",        NULL };
+enum                                   { VAR_X, VAR_Y, VAR_W, VAR_H, VAR_N, VAR_SW, VAR_SH, VAR_VARS_NB };
+
+static av_cold int geq_init(AVFilterContext *ctx, const char *args)
+{
+    GEQContext *geq = ctx->priv;
+    int plane, ret = 0;
+    static const char *shorthand[] = { "lum_expr", "cb_expr", "cr_expr", NULL };
+
+    geq->class = &geq_class;
+    av_opt_set_defaults(geq);
+
+    if ((ret = av_opt_set_from_string(geq, args, shorthand, "=", ":")) < 0)
+        return ret;
+
+    if (!geq->expr_str[0]) {
+        av_log(ctx, AV_LOG_ERROR, "Luminance expression is mandatory\n");
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    if (!geq->expr_str[1] && !geq->expr_str[2]) {
+        /* No chroma at all: fallback on luma */
+        geq->expr_str[1] = av_strdup(geq->expr_str[0]);
+        geq->expr_str[2] = av_strdup(geq->expr_str[0]);
+    } else {
+        /* One chroma unspecified, fallback on the other */
+        if (!geq->expr_str[1]) geq->expr_str[1] = av_strdup(geq->expr_str[2]);
+        if (!geq->expr_str[2]) geq->expr_str[2] = av_strdup(geq->expr_str[1]);
+    }
+
+    if (!geq->expr_str[1] || !geq->expr_str[2]) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    for (plane = 0; plane < 3; plane++) {
+        static double (*p[])(void *, double, double) = { lum, cb, cr };
+        static const char *const func2_names[]    = { "lum", "cb", "cr", "p", NULL };
+        double (*func2[])(void *, double, double) = { lum, cb, cr, p[plane], NULL };
+
+        ret = av_expr_parse(&geq->e[plane], geq->expr_str[plane], var_names,
+                            NULL, NULL, func2_names, func2, 0, ctx);
+        if (ret < 0)
+            break;
+    }
+
+end:
+    return ret;
+}
+
+static int geq_query_formats(AVFilterContext *ctx)
+{
+    static const enum PixelFormat pix_fmts[] = {
+        AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUV422P,  AV_PIX_FMT_YUV420P,
+        AV_PIX_FMT_YUV411P,  AV_PIX_FMT_YUV410P,  AV_PIX_FMT_YUV440P,
+        AV_PIX_FMT_YUVA420P,
+        AV_PIX_FMT_NONE
+    };
+    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+    return 0;
+}
+
+static int geq_config_props(AVFilterLink *inlink)
+{
+    GEQContext *geq = inlink->dst->priv;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
+
+    geq->hsub = desc->log2_chroma_w;
+    geq->vsub = desc->log2_chroma_h;
+    return 0;
+}
+
+static int geq_end_frame(AVFilterLink *inlink)
+{
+    int ret, plane;
+    GEQContext *geq = inlink->dst->priv;
+    AVFilterLink *outlink = inlink->dst->outputs[0];
+    AVFilterBufferRef *outpicref = outlink->out_buf;
+    double values[VAR_VARS_NB] = {
+        [VAR_N] = geq->framenum++,
+    };
+
+    geq->picref = inlink->cur_buf;
+
+    for (plane = 0; plane < 3; plane++) {
+        int x, y;
+        uint8_t *dst = outpicref->data[plane];
+        const int linesize = outpicref->linesize[plane];
+        const int w = inlink->w >> (plane ? geq->hsub : 0);
+        const int h = inlink->h >> (plane ? geq->vsub : 0);
+
+        values[VAR_W]  = w;
+        values[VAR_H]  = h;
+        values[VAR_SW] = w / (double)inlink->w;
+        values[VAR_SH] = h / (double)inlink->h;
+
+        for (y = 0; y < h; y++) {
+            values[VAR_Y] = y;
+            for (x = 0; x < w; x++) {
+                values[VAR_X] = x;
+                dst[x] = av_expr_eval(geq->e[plane], values, geq);
+            }
+            dst += linesize;
+        }
+    }
+
+    if ((ret = ff_draw_slice(outlink, 0, outlink->h, 1)) < 0 ||
+        (ret = ff_end_frame(outlink)) < 0)
+        return ret;
+    return 0;
+}
+
+static av_cold void geq_uninit(AVFilterContext *ctx)
+{
+    int i;
+    GEQContext *geq = ctx->priv;
+
+    for (i = 0; i < FF_ARRAY_ELEMS(geq->e); i++)
+        av_expr_free(geq->e[i]);
+    av_opt_free(geq);
+}
+
+static int null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir) { return 0; }
+
+static const AVFilterPad geq_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .draw_slice   = null_draw_slice,
+        .config_props = geq_config_props,
+        .end_frame    = geq_end_frame,
+        .min_perms    = AV_PERM_READ,
+    },
+    { NULL }
+};
+
+static const AVFilterPad geq_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_vf_geq = {
+    .name          = "geq",
+    .description   = NULL_IF_CONFIG_SMALL("Apply generic equation to each pixel."),
+    .priv_size     = sizeof(GEQContext),
+    .init          = geq_init,
+    .uninit        = geq_uninit,
+    .query_formats = geq_query_formats,
+    .inputs        = geq_inputs,
+    .outputs       = geq_outputs,
+    .priv_class    = &geq_class,
+};
-- 
1.8.0

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