libavfilter/vf_midequalizer.c - third_party/ffmpeg - Git at Google

 /*
  * Copyright (c) 2017 Paul B Mahol
  *
  * 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/imgutils.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 #include "framesync.h"

 typedef struct MidEqualizerContext {
     const AVClass *class;
     int width[2][4], height[2][4];
     int nb_planes;
     int planes;
     int histogram_size;
     float *histogram[2];
     unsigned *cchange;
     FFFrameSync fs;

     void (*midequalizer)(const uint8_t *in0, const uint8_t *in1,
                          uint8_t *dst,
                          ptrdiff_t linesize1, ptrdiff_t linesize2,
                          ptrdiff_t dlinesize,
                          int w0, int h0,
                          int w1, int h1,
                          float *histogram1, float *histogram2,
                          unsigned *cchange, size_t hsize);
 } MidEqualizerContext;

 #define OFFSET(x) offsetof(MidEqualizerContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

 static const AVOption midequalizer_options[] = {
     { "planes", "set planes", OFFSET(planes), AV_OPT_TYPE_INT, {.i64=0xF}, 0, 0xF, FLAGS },
     { NULL }
 };

 AVFILTER_DEFINE_CLASS(midequalizer);

 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P,
         AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P,
         AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVA420P, AV_PIX_FMT_YUV420P,
         AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ420P,
         AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
         AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP,
         AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY9, AV_PIX_FMT_GRAY10, AV_PIX_FMT_GRAY12,
         AV_PIX_FMT_YUV420P9, AV_PIX_FMT_YUV422P9, AV_PIX_FMT_YUV444P9,
         AV_PIX_FMT_YUV420P10, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV444P10,
         AV_PIX_FMT_YUV420P12, AV_PIX_FMT_YUV422P12, AV_PIX_FMT_YUV444P12,
         AV_PIX_FMT_YUV420P14, AV_PIX_FMT_YUV422P14, AV_PIX_FMT_YUV444P14,
         AV_PIX_FMT_GBRP9, AV_PIX_FMT_GBRP10, AV_PIX_FMT_GBRP12, AV_PIX_FMT_GBRP14,
         AV_PIX_FMT_YUVA420P9, AV_PIX_FMT_YUVA422P9, AV_PIX_FMT_YUVA444P9,
         AV_PIX_FMT_YUVA420P10, AV_PIX_FMT_YUVA422P10, AV_PIX_FMT_YUVA444P10,
         AV_PIX_FMT_GBRAP10, AV_PIX_FMT_GBRAP12,
         AV_PIX_FMT_NONE
     };

     return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
 }

 static int process_frame(FFFrameSync *fs)
 {
     AVFilterContext *ctx = fs->parent;
     MidEqualizerContext *s = fs->opaque;
     AVFilterLink *outlink = ctx->outputs[0];
     AVFrame *out, *in0, *in1;
     int ret;

     if ((ret = ff_framesync_get_frame(&s->fs, 0, &in0, 0)) < 0 ||
         (ret = ff_framesync_get_frame(&s->fs, 1, &in1, 0)) < 0)
         return ret;

     if (ctx->is_disabled) {
         out = av_frame_clone(in0);
         if (!out)
             return AVERROR(ENOMEM);
     } else {
         int p;

         out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
         if (!out)
             return AVERROR(ENOMEM);
         av_frame_copy_props(out, in0);

         for (p = 0; p < s->nb_planes; p++) {
             if (!((1 << p) & s->planes)) {
                 av_image_copy_plane(out->data[p], out->linesize[p], in0->data[p], in0->linesize[p],
                                     s->width[0][p] * (1 + (s->histogram_size > 256)), s->height[0][p]);
                 continue;
             }

             s->midequalizer(in0->data[p], in1->data[p],
                             out->data[p],
                             in0->linesize[p], in1->linesize[p],
                             out->linesize[p],
                             s->width[0][p], s->height[0][p],
                             s->width[1][p], s->height[1][p],
                             s->histogram[0], s->histogram[1],
                             s->cchange, s->histogram_size);
         }
     }
     out->pts = av_rescale_q(in0->pts, s->fs.time_base, outlink->time_base);

     return ff_filter_frame(outlink, out);
 }

 static void compute_histogram8(const uint8_t *src, ptrdiff_t linesize,
                                int w, int h, float *histogram, size_t hsize)
 {
     int y, x;

     memset(histogram, 0, hsize * sizeof(*histogram));

     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++) {
             histogram[src[x]] += 1;
         }
         src += linesize;
     }

     for (x = 0; x < hsize - 1; x++) {
         histogram[x + 1] += histogram[x];
         histogram[x] /= hsize;
     }
     histogram[x] /= hsize;
 }

 static void compute_histogram16(const uint16_t *src, ptrdiff_t linesize,
                                 int w, int h, float *histogram, size_t hsize)
 {
     int y, x;

     memset(histogram, 0, hsize * sizeof(*histogram));

     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++) {
             histogram[src[x]] += 1;
         }
         src += linesize;
     }

     for (x = 0; x < hsize - 1; x++) {
         histogram[x + 1] += histogram[x];
         histogram[x] /= hsize;
     }
     histogram[x] /= hsize;
 }

 static void compute_contrast_change(float *histogram1, float *histogram2,
                                     unsigned *cchange, size_t hsize)
 {
     int i;

     for (i = 0; i < hsize; i++) {
         int j;

         for (j = 0; j < hsize && histogram2[j] < histogram1[i]; j++);

         cchange[i] = (i + j) / 2;
     }
 }

 static void midequalizer8(const uint8_t *in0, const uint8_t *in1,
                           uint8_t *dst,
                           ptrdiff_t linesize1, ptrdiff_t linesize2,
                           ptrdiff_t dlinesize,
                           int w0, int h0,
                           int w1, int h1,
                           float *histogram1, float *histogram2,
                           unsigned *cchange,
                           size_t hsize)
 {
     int x, y;

     compute_histogram8(in0, linesize1, w0, h0, histogram1, hsize);
     compute_histogram8(in1, linesize2, w1, h1, histogram2, hsize);

     compute_contrast_change(histogram1, histogram2, cchange, hsize);

     for (y = 0; y < h0; y++) {
         for (x = 0; x < w0; x++) {
             dst[x] = av_clip_uint8(cchange[in0[x]]);
         }
         dst += dlinesize;
         in0 += linesize1;
     }
 }

 static void midequalizer16(const uint8_t *in0, const uint8_t *in1,
                            uint8_t *dst,
                            ptrdiff_t linesize1, ptrdiff_t linesize2,
                            ptrdiff_t dlinesize,
                            int w0, int h0,
                            int w1, int h1,
                            float *histogram1, float *histogram2,
                            unsigned *cchange,
                            size_t hsize)
 {
     const uint16_t *i = (const uint16_t *)in0;
     uint16_t *d = (uint16_t *)dst;
     int x, y;

     compute_histogram16(i, linesize1 / 2, w0, h0, histogram1, hsize);
     compute_histogram16((const uint16_t *)in1, linesize2 / 2, w1, h1, histogram2, hsize);

     compute_contrast_change(histogram1, histogram2, cchange, hsize);

     for (y = 0; y < h0; y++) {
         for (x = 0; x < w0; x++) {
             d[x] = cchange[i[x]];
         }
         d += dlinesize / 2;
         i += linesize1 / 2;
     }
 }

 static int config_input0(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     MidEqualizerContext *s = ctx->priv;
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     int vsub, hsub;

     s->nb_planes = av_pix_fmt_count_planes(inlink->format);

     hsub = desc->log2_chroma_w;
     vsub = desc->log2_chroma_h;

     s->height[0][0] = s->height[0][3] = inlink->h;
     s->width[0][0]  = s->width[0][3]  = inlink->w;
     s->height[0][1] = s->height[0][2] = AV_CEIL_RSHIFT(inlink->h, vsub);
     s->width[0][1]  = s->width[0][2]  = AV_CEIL_RSHIFT(inlink->w, hsub);

     s->histogram_size = 1 << desc->comp[0].depth;

     s->histogram[0] = av_calloc(s->histogram_size, sizeof(float));
     s->histogram[1] = av_calloc(s->histogram_size, sizeof(float));
     s->cchange      = av_calloc(s->histogram_size, sizeof(unsigned));
     if (!s->histogram[0] || !s->histogram[1] || !s->cchange)
         return AVERROR(ENOMEM);

     if (s->histogram_size == 256) {
         s->midequalizer = midequalizer8;
     } else {
         s->midequalizer = midequalizer16;
     }

     return 0;
 }

 static int config_input1(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     MidEqualizerContext *s = ctx->priv;
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     int vsub, hsub;

     s->nb_planes = av_pix_fmt_count_planes(inlink->format);

     hsub = desc->log2_chroma_w;
     vsub = desc->log2_chroma_h;

     s->height[1][0] = s->height[1][3] = inlink->h;
     s->width[1][0]  = s->width[1][3]  = inlink->w;
     s->height[1][1] = s->height[1][2] = AV_CEIL_RSHIFT(inlink->h, vsub);
     s->width[1][1]  = s->width[1][2]  = AV_CEIL_RSHIFT(inlink->w, hsub);

     return 0;
 }

 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     MidEqualizerContext *s = ctx->priv;
     AVFilterLink *in0 = ctx->inputs[0];
     AVFilterLink *in1 = ctx->inputs[1];
     FFFrameSyncIn *in;
     int ret;

     if (in0->format != in1->format) {
         av_log(ctx, AV_LOG_ERROR, "inputs must be of same pixel format\n");
         return AVERROR(EINVAL);
     }

     outlink->w = in0->w;
     outlink->h = in0->h;
     outlink->time_base = in0->time_base;
     outlink->sample_aspect_ratio = in0->sample_aspect_ratio;
     outlink->frame_rate = in0->frame_rate;

     if ((ret = ff_framesync_init(&s->fs, ctx, 2)) < 0)
         return ret;

     in = s->fs.in;
     in[0].time_base = in0->time_base;
     in[1].time_base = in1->time_base;
     in[0].sync   = 1;
     in[0].before = EXT_STOP;
     in[0].after  = EXT_INFINITY;
     in[1].sync   = 1;
     in[1].before = EXT_STOP;
     in[1].after  = EXT_INFINITY;
     s->fs.opaque   = s;
     s->fs.on_event = process_frame;

     return ff_framesync_configure(&s->fs);
 }

 static int activate(AVFilterContext *ctx)
 {
     MidEqualizerContext *s = ctx->priv;
     return ff_framesync_activate(&s->fs);
 }

 static av_cold void uninit(AVFilterContext *ctx)
 {
     MidEqualizerContext *s = ctx->priv;

     ff_framesync_uninit(&s->fs);
     av_freep(&s->histogram[0]);
     av_freep(&s->histogram[1]);
     av_freep(&s->cchange);
 }

 static const AVFilterPad midequalizer_inputs[] = {
     {
         .name         = "in0",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_input0,
     },
     {
         .name         = "in1",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_input1,
     },
     { NULL }
 };

 static const AVFilterPad midequalizer_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
     },
     { NULL }
 };

 AVFilter ff_vf_midequalizer = {
     .name          = "midequalizer",
     .description   = NULL_IF_CONFIG_SMALL("Apply Midway Equalization."),
     .priv_size     = sizeof(MidEqualizerContext),
     .uninit        = uninit,
     .query_formats = query_formats,
     .activate      = activate,
     .inputs        = midequalizer_inputs,
     .outputs       = midequalizer_outputs,
     .priv_class    = &midequalizer_class,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
 };
	/*
	* Copyright (c) 2017 Paul B Mahol
	*
	* 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/imgutils.h"
	#include "libavutil/pixdesc.h"
	#include "libavutil/opt.h"
	#include "avfilter.h"
	#include "formats.h"
	#include "internal.h"
	#include "video.h"
	#include "framesync.h"

	typedef struct MidEqualizerContext {
	const AVClass *class;
	int width[2][4], height[2][4];
	int nb_planes;
	int planes;
	int histogram_size;
	float *histogram[2];
	unsigned *cchange;
	FFFrameSync fs;

	void (midequalizer)(const uint8_t in0, const uint8_t *in1,
	uint8_t *dst,
	ptrdiff_t linesize1, ptrdiff_t linesize2,
	ptrdiff_t dlinesize,
	int w0, int h0,
	int w1, int h1,
	float histogram1, float histogram2,
	unsigned *cchange, size_t hsize);
	} MidEqualizerContext;

	#define OFFSET(x) offsetof(MidEqualizerContext, x)
	#define FLAGS AV_OPT_FLAG_FILTERING_PARAM\|AV_OPT_FLAG_VIDEO_PARAM

	static const AVOption midequalizer_options[] = {
	{ "planes", "set planes", OFFSET(planes), AV_OPT_TYPE_INT, {.i64=0xF}, 0, 0xF, FLAGS },
	{ NULL }
	};

	AVFILTER_DEFINE_CLASS(midequalizer);

	static int query_formats(AVFilterContext *ctx)
	{
	static const enum AVPixelFormat pix_fmts[] = {
	AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P,
	AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P,
	AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVA420P, AV_PIX_FMT_YUV420P,
	AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ420P,
	AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
	AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP,
	AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY9, AV_PIX_FMT_GRAY10, AV_PIX_FMT_GRAY12,
	AV_PIX_FMT_YUV420P9, AV_PIX_FMT_YUV422P9, AV_PIX_FMT_YUV444P9,
	AV_PIX_FMT_YUV420P10, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV444P10,
	AV_PIX_FMT_YUV420P12, AV_PIX_FMT_YUV422P12, AV_PIX_FMT_YUV444P12,
	AV_PIX_FMT_YUV420P14, AV_PIX_FMT_YUV422P14, AV_PIX_FMT_YUV444P14,
	AV_PIX_FMT_GBRP9, AV_PIX_FMT_GBRP10, AV_PIX_FMT_GBRP12, AV_PIX_FMT_GBRP14,
	AV_PIX_FMT_YUVA420P9, AV_PIX_FMT_YUVA422P9, AV_PIX_FMT_YUVA444P9,
	AV_PIX_FMT_YUVA420P10, AV_PIX_FMT_YUVA422P10, AV_PIX_FMT_YUVA444P10,
	AV_PIX_FMT_GBRAP10, AV_PIX_FMT_GBRAP12,
	AV_PIX_FMT_NONE
	};

	return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
	}

	static int process_frame(FFFrameSync *fs)
	{
	AVFilterContext *ctx = fs->parent;
	MidEqualizerContext *s = fs->opaque;
	AVFilterLink *outlink = ctx->outputs[0];
	AVFrame out, in0, *in1;
	int ret;

	if ((ret = ff_framesync_get_frame(&s->fs, 0, &in0, 0)) < 0 \|\|
	(ret = ff_framesync_get_frame(&s->fs, 1, &in1, 0)) < 0)
	return ret;

	if (ctx->is_disabled) {
	out = av_frame_clone(in0);
	if (!out)
	return AVERROR(ENOMEM);
	} else {
	int p;

	out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
	if (!out)
	return AVERROR(ENOMEM);
	av_frame_copy_props(out, in0);

	for (p = 0; p < s->nb_planes; p++) {
	if (!((1 << p) & s->planes)) {
	av_image_copy_plane(out->data[p], out->linesize[p], in0->data[p], in0->linesize[p],
	s->width[0][p] * (1 + (s->histogram_size > 256)), s->height[0][p]);
	continue;
	}

	s->midequalizer(in0->data[p], in1->data[p],
	out->data[p],
	in0->linesize[p], in1->linesize[p],
	out->linesize[p],
	s->width[0][p], s->height[0][p],
	s->width[1][p], s->height[1][p],
	s->histogram[0], s->histogram[1],
	s->cchange, s->histogram_size);
	}
	}
	out->pts = av_rescale_q(in0->pts, s->fs.time_base, outlink->time_base);

	return ff_filter_frame(outlink, out);
	}

	static void compute_histogram8(const uint8_t *src, ptrdiff_t linesize,
	int w, int h, float *histogram, size_t hsize)
	{
	int y, x;

	memset(histogram, 0, hsize * sizeof(*histogram));

	for (y = 0; y < h; y++) {
	for (x = 0; x < w; x++) {
	histogram[src[x]] += 1;
	}
	src += linesize;
	}

	for (x = 0; x < hsize - 1; x++) {
	histogram[x + 1] += histogram[x];
	histogram[x] /= hsize;
	}
	histogram[x] /= hsize;
	}

	static void compute_histogram16(const uint16_t *src, ptrdiff_t linesize,
	int w, int h, float *histogram, size_t hsize)
	{
	int y, x;

	memset(histogram, 0, hsize * sizeof(*histogram));

	for (y = 0; y < h; y++) {
	for (x = 0; x < w; x++) {
	histogram[src[x]] += 1;
	}
	src += linesize;
	}

	for (x = 0; x < hsize - 1; x++) {
	histogram[x + 1] += histogram[x];
	histogram[x] /= hsize;
	}
	histogram[x] /= hsize;
	}

	static void compute_contrast_change(float histogram1, float histogram2,
	unsigned *cchange, size_t hsize)
	{
	int i;

	for (i = 0; i < hsize; i++) {
	int j;

	for (j = 0; j < hsize && histogram2[j] < histogram1[i]; j++);

	cchange[i] = (i + j) / 2;
	}
	}

	static void midequalizer8(const uint8_t in0, const uint8_t in1,
	uint8_t *dst,
	ptrdiff_t linesize1, ptrdiff_t linesize2,
	ptrdiff_t dlinesize,
	int w0, int h0,
	int w1, int h1,
	float histogram1, float histogram2,
	unsigned *cchange,
	size_t hsize)
	{
	int x, y;

	compute_histogram8(in0, linesize1, w0, h0, histogram1, hsize);
	compute_histogram8(in1, linesize2, w1, h1, histogram2, hsize);

	compute_contrast_change(histogram1, histogram2, cchange, hsize);

	for (y = 0; y < h0; y++) {
	for (x = 0; x < w0; x++) {
	dst[x] = av_clip_uint8(cchange[in0[x]]);
	}
	dst += dlinesize;
	in0 += linesize1;
	}
	}

	static void midequalizer16(const uint8_t in0, const uint8_t in1,
	uint8_t *dst,
	ptrdiff_t linesize1, ptrdiff_t linesize2,
	ptrdiff_t dlinesize,
	int w0, int h0,
	int w1, int h1,
	float histogram1, float histogram2,
	unsigned *cchange,
	size_t hsize)
	{
	const uint16_t i = (const uint16_t )in0;
	uint16_t d = (uint16_t )dst;
	int x, y;

	compute_histogram16(i, linesize1 / 2, w0, h0, histogram1, hsize);
	compute_histogram16((const uint16_t *)in1, linesize2 / 2, w1, h1, histogram2, hsize);

	compute_contrast_change(histogram1, histogram2, cchange, hsize);

	for (y = 0; y < h0; y++) {
	for (x = 0; x < w0; x++) {
	d[x] = cchange[i[x]];
	}
	d += dlinesize / 2;
	i += linesize1 / 2;
	}
	}

	static int config_input0(AVFilterLink *inlink)
	{
	AVFilterContext *ctx = inlink->dst;
	MidEqualizerContext *s = ctx->priv;
	const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
	int vsub, hsub;

	s->nb_planes = av_pix_fmt_count_planes(inlink->format);

	hsub = desc->log2_chroma_w;
	vsub = desc->log2_chroma_h;

	s->height[0][0] = s->height[0][3] = inlink->h;
	s->width[0][0] = s->width[0][3] = inlink->w;
	s->height[0][1] = s->height[0][2] = AV_CEIL_RSHIFT(inlink->h, vsub);
	s->width[0][1] = s->width[0][2] = AV_CEIL_RSHIFT(inlink->w, hsub);

	s->histogram_size = 1 << desc->comp[0].depth;

	s->histogram[0] = av_calloc(s->histogram_size, sizeof(float));
	s->histogram[1] = av_calloc(s->histogram_size, sizeof(float));
	s->cchange = av_calloc(s->histogram_size, sizeof(unsigned));
	if (!s->histogram[0] \|\| !s->histogram[1] \|\| !s->cchange)
	return AVERROR(ENOMEM);

	if (s->histogram_size == 256) {
	s->midequalizer = midequalizer8;
	} else {
	s->midequalizer = midequalizer16;
	}

	return 0;
	}

	static int config_input1(AVFilterLink *inlink)
	{
	AVFilterContext *ctx = inlink->dst;
	MidEqualizerContext *s = ctx->priv;
	const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
	int vsub, hsub;

	s->nb_planes = av_pix_fmt_count_planes(inlink->format);

	hsub = desc->log2_chroma_w;
	vsub = desc->log2_chroma_h;

	s->height[1][0] = s->height[1][3] = inlink->h;
	s->width[1][0] = s->width[1][3] = inlink->w;
	s->height[1][1] = s->height[1][2] = AV_CEIL_RSHIFT(inlink->h, vsub);
	s->width[1][1] = s->width[1][2] = AV_CEIL_RSHIFT(inlink->w, hsub);

	return 0;
	}

	static int config_output(AVFilterLink *outlink)
	{
	AVFilterContext *ctx = outlink->src;
	MidEqualizerContext *s = ctx->priv;
	AVFilterLink *in0 = ctx->inputs[0];
	AVFilterLink *in1 = ctx->inputs[1];
	FFFrameSyncIn *in;
	int ret;

	if (in0->format != in1->format) {
	av_log(ctx, AV_LOG_ERROR, "inputs must be of same pixel format\n");
	return AVERROR(EINVAL);
	}

	outlink->w = in0->w;
	outlink->h = in0->h;
	outlink->time_base = in0->time_base;
	outlink->sample_aspect_ratio = in0->sample_aspect_ratio;
	outlink->frame_rate = in0->frame_rate;

	if ((ret = ff_framesync_init(&s->fs, ctx, 2)) < 0)
	return ret;

	in = s->fs.in;
	in[0].time_base = in0->time_base;
	in[1].time_base = in1->time_base;
	in[0].sync = 1;
	in[0].before = EXT_STOP;
	in[0].after = EXT_INFINITY;
	in[1].sync = 1;
	in[1].before = EXT_STOP;
	in[1].after = EXT_INFINITY;
	s->fs.opaque = s;
	s->fs.on_event = process_frame;

	return ff_framesync_configure(&s->fs);
	}

	static int activate(AVFilterContext *ctx)
	{
	MidEqualizerContext *s = ctx->priv;
	return ff_framesync_activate(&s->fs);
	}

	static av_cold void uninit(AVFilterContext *ctx)
	{
	MidEqualizerContext *s = ctx->priv;

	ff_framesync_uninit(&s->fs);
	av_freep(&s->histogram[0]);
	av_freep(&s->histogram[1]);
	av_freep(&s->cchange);
	}

	static const AVFilterPad midequalizer_inputs[] = {
	{
	.name = "in0",
	.type = AVMEDIA_TYPE_VIDEO,
	.config_props = config_input0,
	},
	{
	.name = "in1",
	.type = AVMEDIA_TYPE_VIDEO,
	.config_props = config_input1,
	},
	{ NULL }
	};

	static const AVFilterPad midequalizer_outputs[] = {
	{
	.name = "default",
	.type = AVMEDIA_TYPE_VIDEO,
	.config_props = config_output,
	},
	{ NULL }
	};

	AVFilter ff_vf_midequalizer = {
	.name = "midequalizer",
	.description = NULL_IF_CONFIG_SMALL("Apply Midway Equalization."),
	.priv_size = sizeof(MidEqualizerContext),
	.uninit = uninit,
	.query_formats = query_formats,
	.activate = activate,
	.inputs = midequalizer_inputs,
	.outputs = midequalizer_outputs,
	.priv_class = &midequalizer_class,
	.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
	};