avfilter: add vif filter

This is Visual Information Fidelity (VIF) filter and one of the component
filters of VMAF. It outputs the average VIF score over all frames.

Signed-off-by: Ashish Singh <ashk43712@gmail.com>

7 files changed, 709 insertions, 1 deletions

diff --git a/Changelog b/Changelog
index 3c7015bd83..6471b35417 100644
--- a/Changelog
+++ b/Changelog
@@ -73,6 +73,7 @@ version <next>:
 - exposure video filter
 - monochrome video filter
 - setts bitstream filter
+- vif video filter
 
 
 version 4.3:
diff --git a/doc/filters.texi b/doc/filters.texi
index 9dfc0ec67f..426cb158da 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -21266,6 +21266,27 @@ otherwise colors will be less saturated, more towards gray.
 
 This filter supports the all above options as @ref{commands}.
 
+@section vif
+
+Obtain the average VIF (Visual Information Fidelity) between two input videos.
+
+This filter takes two input videos.
+
+Both input videos must have the same resolution and pixel format for
+this filter to work correctly. Also it assumes that both inputs
+have the same number of frames, which are compared one by one.
+
+The obtained average VIF score is printed through the logging system.
+
+The filter stores the calculated VIF score of each frame.
+
+In the below example the input file @file{main.mpg} being processed is compared
+with the reference file @file{ref.mpg}.
+
+@example
+ffmpeg -i main.mpg -i ref.mpg -lavfi vif -f null -
+@end example
+
 @anchor{vignette}
 @section vignette
 
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 682d368bf5..05bb2d2031 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -470,6 +470,7 @@ OBJS-$(CONFIG_VFRDET_FILTER)                 += vf_vfrdet.o
 OBJS-$(CONFIG_VIBRANCE_FILTER)               += vf_vibrance.o
 OBJS-$(CONFIG_VIDSTABDETECT_FILTER)          += vidstabutils.o vf_vidstabdetect.o
 OBJS-$(CONFIG_VIDSTABTRANSFORM_FILTER)       += vidstabutils.o vf_vidstabtransform.o
+OBJS-$(CONFIG_VIF_FILTER)                    += vf_vif.o framesync.o
 OBJS-$(CONFIG_VIGNETTE_FILTER)               += vf_vignette.o
 OBJS-$(CONFIG_VMAFMOTION_FILTER)             += vf_vmafmotion.o framesync.o
 OBJS-$(CONFIG_VPP_QSV_FILTER)                += vf_vpp_qsv.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index f1131a923b..452c030706 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -448,6 +448,7 @@ extern AVFilter ff_vf_vfrdet;
 extern AVFilter ff_vf_vibrance;
 extern AVFilter ff_vf_vidstabdetect;
 extern AVFilter ff_vf_vidstabtransform;
+extern AVFilter ff_vf_vif;
 extern AVFilter ff_vf_vignette;
 extern AVFilter ff_vf_vmafmotion;
 extern AVFilter ff_vf_vpp_qsv;
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 9c8e224fc6..52154a32b1 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   7
-#define LIBAVFILTER_VERSION_MINOR 106
+#define LIBAVFILTER_VERSION_MINOR 107
 #define LIBAVFILTER_VERSION_MICRO 100
 
 
diff --git a/libavfilter/vf_vif.c b/libavfilter/vf_vif.c
new file mode 100644
index 0000000000..c1079c75d9
--- /dev/null
+++ b/libavfilter/vf_vif.c
@@ -0,0 +1,654 @@
+/*
+ * Copyright (c) 2017 Ronald S. Bultje <rsbultje@gmail.com>
+ * Copyright (c) 2017 Ashish Pratap Singh <ashk43712@gmail.com>
+ * Copyright (c) 2021 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
+ */
+
+/**
+ * @file
+ * Calculate VIF between two input videos.
+ */
+
+#include <float.h>
+
+#include "libavutil/avstring.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "avfilter.h"
+#include "framesync.h"
+#include "drawutils.h"
+#include "formats.h"
+#include "internal.h"
+#include "vif.h"
+#include "video.h"
+
+typedef struct VIFContext {
+    const AVClass *class;
+    FFFrameSync fs;
+    const AVPixFmtDescriptor *desc;
+    int width;
+    int height;
+    int nb_threads;
+    float *data_buf[13];
+    float **temp;
+    float *ref_data;
+    float *main_data;
+    double vif_sum[4];
+    double vif_min[4];
+    double vif_max[4];
+    uint64_t nb_frames;
+} VIFContext;
+
+#define OFFSET(x) offsetof(VIFContext, x)
+
+static const AVOption vif_options[] = {
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(vif);
+
+static const uint8_t vif_filter1d_width1[4] = { 17, 9, 5, 3 };
+
+static const float vif_filter1d_table[4][17] =
+{
+    {
+        0.00745626912, 0.0142655009, 0.0250313189, 0.0402820669, 0.0594526194,
+        0.0804751068, 0.0999041125, 0.113746084, 0.118773937, 0.113746084,
+        0.0999041125, 0.0804751068, 0.0594526194, 0.0402820669, 0.0250313189,
+        0.0142655009, 0.00745626912
+    },
+    {
+        0.0189780835, 0.0558981746, 0.120920904, 0.192116052, 0.224173605,
+        0.192116052, 0.120920904, 0.0558981746, 0.0189780835
+    },
+    {
+        0.054488685, 0.244201347, 0.402619958, 0.244201347, 0.054488685
+    },
+    {
+        0.166378498, 0.667243004, 0.166378498
+    }
+};
+
+typedef struct ThreadData {
+    const float *filter;
+    const float *src;
+    float *dst;
+    int w, h;
+    int src_stride;
+    int dst_stride;
+    int filter_width;
+    float **temp;
+} ThreadData;
+
+static void vif_dec2(const float *src, float *dst, int w, int h,
+                     int src_stride, int dst_stride)
+{
+    const int dst_px_stride = dst_stride / 2;
+
+    for (int i = 0; i < h / 2; i++) {
+        for (int j = 0; j < w / 2; j++)
+            dst[i * dst_px_stride + j] = src[(i * 2) * src_stride + (j * 2)];
+    }
+}
+
+static void vif_statistic(const float *mu1_sq, const float *mu2_sq,
+                          const float *mu1_mu2, const float *xx_filt,
+                          const float *yy_filt, const float *xy_filt,
+                          float *num, float *den, int w, int h)
+{
+    static const float sigma_nsq = 2;
+    static const float sigma_max_inv = 4.0/(255.0*255.0);
+
+    float mu1_sq_val, mu2_sq_val, mu1_mu2_val, xx_filt_val, yy_filt_val, xy_filt_val;
+    float sigma1_sq, sigma2_sq, sigma12, g, sv_sq, eps = 1.0e-10f;
+    float gain_limit = 100.f;
+    float num_val, den_val;
+    float accum_num = 0.0f;
+    float accum_den = 0.0f;
+
+    for (int i = 0; i < h; i++) {
+        float accum_inner_num = 0.f;
+        float accum_inner_den = 0.f;
+
+        for (int j = 0; j < w; j++) {
+            mu1_sq_val  = mu1_sq[i * w + j];
+            mu2_sq_val  = mu2_sq[i * w + j];
+            mu1_mu2_val = mu1_mu2[i * w + j];
+            xx_filt_val = xx_filt[i * w + j];
+            yy_filt_val = yy_filt[i * w + j];
+            xy_filt_val = xy_filt[i * w + j];
+
+            sigma1_sq = xx_filt_val - mu1_sq_val;
+            sigma2_sq = yy_filt_val - mu2_sq_val;
+            sigma12   = xy_filt_val - mu1_mu2_val;
+
+            sigma1_sq = FFMAX(sigma1_sq, 0.0f);
+            sigma2_sq = FFMAX(sigma2_sq, 0.0f);
+            sigma12   = FFMAX(sigma12,   0.0f);
+
+            g = sigma12 / (sigma1_sq + eps);
+            sv_sq = sigma2_sq - g * sigma12;
+
+            if (sigma1_sq < eps) {
+                g = 0.0f;
+                sv_sq = sigma2_sq;
+                sigma1_sq = 0.0f;
+            }
+
+            if (sigma2_sq < eps) {
+                g = 0.0f;
+                sv_sq = 0.0f;
+            }
+
+            if (g < 0.0f) {
+                sv_sq = sigma2_sq;
+                g = 0.0f;
+            }
+            sv_sq = FFMAX(sv_sq, eps);
+
+            g = FFMIN(g, gain_limit);
+
+            num_val = log2f(1.0f + g * g * sigma1_sq / (sv_sq + sigma_nsq));
+            den_val = log2f(1.0f + sigma1_sq / sigma_nsq);
+
+            if (sigma12 < 0.0f)
+                num_val = 0.0f;
+
+            if (sigma1_sq < sigma_nsq) {
+                num_val = 1.0f - sigma2_sq * sigma_max_inv;
+                den_val = 1.0f;
+            }
+
+            accum_inner_num += num_val;
+            accum_inner_den += den_val;
+        }
+
+        accum_num += accum_inner_num;
+        accum_den += accum_inner_den;
+    }
+
+    num[0] = accum_num;
+    den[0] = accum_den;
+}
+
+static void vif_xx_yy_xy(const float *x, const float *y, float *xx, float *yy,
+                         float *xy, int w, int h)
+{
+    for (int i = 0; i < h; i++) {
+        for (int j = 0; j < w; j++) {
+            float xval = x[j];
+            float yval = y[j];
+            float xxval = xval * xval;
+            float yyval = yval * yval;
+            float xyval = xval * yval;
+
+            xx[j] = xxval;
+            yy[j] = yyval;
+            xy[j] = xyval;
+        }
+
+        xx += w;
+        yy += w;
+        xy += w;
+        x  += w;
+        y  += w;
+    }
+}
+
+static int vif_filter1d(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+    ThreadData *td = arg;
+    const float *filter = td->filter;
+    const float *src = td->src;
+    float *dst = td->dst;
+    int w = td->w;
+    int h = td->h;
+    int src_stride = td->src_stride;
+    int dst_stride = td->dst_stride;
+    int filt_w = td->filter_width;
+    float *temp = td->temp[jobnr];
+    const int slice_start = (h * jobnr) / nb_jobs;
+    const int slice_end = (h * (jobnr+1)) / nb_jobs;
+
+    for (int i = slice_start; i < slice_end; i++) {
+        /** Vertical pass. */
+        for (int j = 0; j < w; j++) {
+            float sum = 0.f;
+
+            if (i >= filt_w / 2 && i < h - filt_w / 2 - 1) {
+                for (int filt_i = 0; filt_i < filt_w; filt_i++) {
+                    const float filt_coeff = filter[filt_i];
+                    float img_coeff;
+                    int ii = i - filt_w / 2 + filt_i;
+
+                    img_coeff = src[ii * src_stride + j];
+                    sum += filt_coeff * img_coeff;
+                }
+            } else {
+                for (int filt_i = 0; filt_i < filt_w; filt_i++) {
+                    const float filt_coeff = filter[filt_i];
+                    int ii = i - filt_w / 2 + filt_i;
+                    float img_coeff;
+
+                    ii = ii < 0 ? -ii : (ii >= h ? 2 * h - ii - 1 : ii);
+
+                    img_coeff = src[ii * src_stride + j];
+                    sum += filt_coeff * img_coeff;
+                }
+            }
+
+            temp[j] = sum;
+        }
+
+        /** Horizontal pass. */
+        for (int j = 0; j < w; j++) {
+            float sum = 0.f;
+
+            if (j >= filt_w / 2 && j < w - filt_w / 2 - 1) {
+                for (int filt_j = 0; filt_j < filt_w; filt_j++) {
+                    const float filt_coeff = filter[filt_j];
+                    int jj = j - filt_w / 2 + filt_j;
+                    float img_coeff;
+
+                    img_coeff = temp[jj];
+                    sum += filt_coeff * img_coeff;
+                }
+            } else {
+                for (int filt_j = 0; filt_j < filt_w; filt_j++) {
+                    const float filt_coeff = filter[filt_j];
+                    int jj = j - filt_w / 2 + filt_j;
+                    float img_coeff;
+
+                    jj = jj < 0 ? -jj : (jj >= w ? 2 * w - jj - 1 : jj);
+
+                    img_coeff = temp[jj];
+                    sum += filt_coeff * img_coeff;
+                }
+            }
+
+            dst[i * dst_stride + j] = sum;
+        }
+    }
+
+    return 0;
+}
+
+int ff_compute_vif2(AVFilterContext *ctx,
+                    const float *ref, const float *main, int w, int h,
+                    int ref_stride, int main_stride, float *score,
+                    float *data_buf[14], float **temp,
+                    int gnb_threads)
+{
+    ThreadData td;
+    float *ref_scale = data_buf[0];
+    float *main_scale = data_buf[1];
+    float *ref_sq = data_buf[2];
+    float *main_sq = data_buf[3];
+    float *ref_main = data_buf[4];
+    float *mu1 = data_buf[5];
+    float *mu2 = data_buf[6];
+    float *mu1_sq = data_buf[7];
+    float *mu2_sq = data_buf[8];
+    float *mu1_mu2 = data_buf[9];
+    float *ref_sq_filt = data_buf[10];
+    float *main_sq_filt = data_buf[11];
+    float *ref_main_filt = data_buf[12];
+
+    float *curr_ref_scale = (float *)ref;
+    float *curr_main_scale = (float *)main;
+    int curr_ref_stride = ref_stride;
+    int curr_main_stride = main_stride;
+
+    float num = 0.f;
+    float den = 0.f;
+
+    for (int scale = 0; scale < 4; scale++) {
+        const float *filter = vif_filter1d_table[scale];
+        int filter_width = vif_filter1d_width1[scale];
+        const int nb_threads = FFMIN(h, gnb_threads);
+        int buf_valid_w = w;
+        int buf_valid_h = h;
+
+        td.filter = filter;
+        td.filter_width = filter_width;
+
+        if (scale > 0) {
+            td.src = curr_ref_scale;
+            td.dst = mu1;
+            td.w = w;
+            td.h = h;
+            td.src_stride = curr_ref_stride;
+            td.dst_stride = w;
+            td.temp = temp;
+            ctx->internal->execute(ctx, vif_filter1d, &td, NULL, nb_threads);
+
+            td.src = curr_main_scale;
+            td.dst = mu2;
+            td.src_stride = curr_main_stride;
+            ctx->internal->execute(ctx, vif_filter1d, &td, NULL, nb_threads);
+
+            vif_dec2(mu1, ref_scale, buf_valid_w, buf_valid_h, w, w);
+            vif_dec2(mu2, main_scale, buf_valid_w, buf_valid_h, w, w);
+
+            w = buf_valid_w / 2;
+            h = buf_valid_h / 2;
+
+            buf_valid_w = w;
+            buf_valid_h = h;
+
+            curr_ref_scale = ref_scale;
+            curr_main_scale = main_scale;
+
+            curr_ref_stride = w;
+            curr_main_stride = w;
+        }
+
+        td.src = curr_ref_scale;
+        td.dst = mu1;
+        td.w = w;
+        td.h = h;
+        td.src_stride = curr_ref_stride;
+        td.dst_stride = w;
+        td.temp = temp;
+        ctx->internal->execute(ctx, vif_filter1d, &td, NULL, nb_threads);
+
+        td.src = curr_main_scale;
+        td.dst = mu2;
+        td.src_stride = curr_main_stride;
+        ctx->internal->execute(ctx, vif_filter1d, &td, NULL, nb_threads);
+
+        vif_xx_yy_xy(mu1, mu2, mu1_sq, mu2_sq, mu1_mu2, w, h);
+
+        vif_xx_yy_xy(curr_ref_scale, curr_main_scale, ref_sq, main_sq, ref_main, w, h);
+
+        td.src = ref_sq;
+        td.dst = ref_sq_filt;
+        td.src_stride = w;
+        ctx->internal->execute(ctx, vif_filter1d, &td, NULL, nb_threads);
+
+        td.src = main_sq;
+        td.dst = main_sq_filt;
+        td.src_stride = w;
+        ctx->internal->execute(ctx, vif_filter1d, &td, NULL, nb_threads);
+
+        td.src = ref_main;
+        td.dst = ref_main_filt;
+        ctx->internal->execute(ctx, vif_filter1d, &td, NULL, nb_threads);
+
+        vif_statistic(mu1_sq, mu2_sq, mu1_mu2, ref_sq_filt, main_sq_filt,
+                      ref_main_filt, &num, &den, w, h);
+
+        score[scale] = den <= FLT_EPSILON ? 1.f : num / den;
+    }
+
+    return 0;
+}
+
+#define offset_fn(type, bits)                            \
+static void offset_##bits##bit(VIFContext *s,            \
+                               const AVFrame *ref,       \
+                               AVFrame *main, int stride)\
+{                                                        \
+    int w = s->width;                                    \
+    int h = s->height;                                   \
+                                                         \
+    int ref_stride = ref->linesize[0];                   \
+    int main_stride = main->linesize[0];                 \
+                                                         \
+    const type *ref_ptr = (const type *) ref->data[0];   \
+    const type *main_ptr = (const type *) main->data[0]; \
+                                            \
+    float *ref_ptr_data = s->ref_data;      \
+    float *main_ptr_data = s->main_data;    \
+                                            \
+    for (int i = 0; i < h; i++) {           \
+        for (int j = 0; j < w; j++) {       \
+            ref_ptr_data[j] = ref_ptr[j] - 128.f;   \
+            main_ptr_data[j] = main_ptr[j] - 128.f; \
+        }                                   \
+        ref_ptr += ref_stride / sizeof(type);   \
+        ref_ptr_data += w;                      \
+        main_ptr += main_stride / sizeof(type); \
+        main_ptr_data += w;                     \
+    } \
+}
+
+offset_fn(uint8_t, 8);
+offset_fn(uint16_t, 10);
+
+static void set_meta(AVDictionary **metadata, const char *key, float d)
+{
+    char value[257];
+    snprintf(value, sizeof(value), "%f", d);
+    av_dict_set(metadata, key, value, 0);
+}
+
+static AVFrame *do_vif(AVFilterContext *ctx, AVFrame *main, const AVFrame *ref)
+{
+    VIFContext *s = ctx->priv;
+    AVDictionary **metadata = &main->metadata;
+    float score[4];
+
+    if (s->desc->comp[0].depth <= 8) {
+        offset_8bit(s, ref, main, s->width);
+    } else {
+        offset_10bit(s, ref, main, s->width);
+    }
+
+    ff_compute_vif2(ctx,
+                    s->ref_data, s->main_data, s->width,
+                    s->height, s->width, s->width,
+                    score, s->data_buf, s->temp,
+                    s->nb_threads);
+
+    set_meta(metadata, "lavfi.vif.scale.0", score[0]);
+    set_meta(metadata, "lavfi.vif.scale.1", score[1]);
+    set_meta(metadata, "lavfi.vif.scale.2", score[2]);
+    set_meta(metadata, "lavfi.vif.scale.3", score[3]);
+
+    for (int i = 0; i < 4; i++) {
+        s->vif_min[i]  = FFMIN(s->vif_min[i], score[i]);
+        s->vif_max[i]  = FFMAX(s->vif_max[i], score[i]);
+        s->vif_sum[i] += score[i];
+    }
+
+    s->nb_frames++;
+
+    return main;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum AVPixelFormat pix_fmts[] = {
+        AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV420P,
+        AV_PIX_FMT_YUV444P10LE, AV_PIX_FMT_YUV422P10LE, AV_PIX_FMT_YUV420P10LE,
+        AV_PIX_FMT_NONE
+    };
+
+    AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
+    if (!fmts_list)
+        return AVERROR(ENOMEM);
+    return ff_set_common_formats(ctx, fmts_list);
+}
+
+static int config_input_ref(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx  = inlink->dst;
+    VIFContext *s = ctx->priv;
+
+    if (ctx->inputs[0]->w != ctx->inputs[1]->w ||
+        ctx->inputs[0]->h != ctx->inputs[1]->h) {
+        av_log(ctx, AV_LOG_ERROR, "Width and height of input videos must be same.\n");
+        return AVERROR(EINVAL);
+    }
+    if (ctx->inputs[0]->format != ctx->inputs[1]->format) {
+        av_log(ctx, AV_LOG_ERROR, "Inputs must be of same pixel format.\n");
+        return AVERROR(EINVAL);
+    }
+
+    s->desc = av_pix_fmt_desc_get(inlink->format);
+    s->width = ctx->inputs[0]->w;
+    s->height = ctx->inputs[0]->h;
+    s->nb_threads = ff_filter_get_nb_threads(ctx);
+
+    for (int i = 0; i < 4; i++) {
+        s->vif_min[i] =  DBL_MAX;
+        s->vif_max[i] = -DBL_MAX;
+    }
+
+    for (int i = 0; i < 13; i++) {
+        if (!(s->data_buf[i] = av_calloc(s->width, s->height * sizeof(float))))
+            return AVERROR(ENOMEM);
+    }
+
+    if (!(s->ref_data = av_calloc(s->width, s->height * sizeof(float))))
+        return AVERROR(ENOMEM);
+
+    if (!(s->main_data = av_calloc(s->width, s->height * sizeof(float))))
+        return AVERROR(ENOMEM);
+
+    if (!(s->temp = av_calloc(s->nb_threads, sizeof(s->temp[0]))))
+        return AVERROR(ENOMEM);
+
+    for (int i = 0; i < s->nb_threads; i++) {
+        if (!(s->temp[i] = av_calloc(s->width, sizeof(float))))
+            return AVERROR(ENOMEM);
+    }
+
+    return 0;
+}
+
+static int process_frame(FFFrameSync *fs)
+{
+    AVFilterContext *ctx = fs->parent;
+    VIFContext *s = fs->opaque;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AVFrame *out, *main = NULL, *ref = NULL;
+    int ret;
+
+    ret = ff_framesync_dualinput_get(fs, &main, &ref);
+    if (ret < 0)
+        return ret;
+
+    if (ctx->is_disabled || !ref) {
+        out = main;
+    } else {
+        out = do_vif(ctx, main, ref);
+    }
+
+    out->pts = av_rescale_q(s->fs.pts, s->fs.time_base, outlink->time_base);
+
+    return ff_filter_frame(outlink, out);
+}
+
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    VIFContext *s = ctx->priv;
+    AVFilterLink *mainlink = ctx->inputs[0];
+    FFFrameSyncIn *in;
+    int ret;
+
+    outlink->w = mainlink->w;
+    outlink->h = mainlink->h;
+    outlink->time_base = mainlink->time_base;
+    outlink->sample_aspect_ratio = mainlink->sample_aspect_ratio;
+    outlink->frame_rate = mainlink->frame_rate;
+    if ((ret = ff_framesync_init(&s->fs, ctx, 2)) < 0)
+        return ret;
+
+    in = s->fs.in;
+    in[0].time_base = mainlink->time_base;
+    in[1].time_base = ctx->inputs[1]->time_base;
+    in[0].sync   = 2;
+    in[0].before = EXT_STOP;
+    in[0].after  = EXT_STOP;
+    in[1].sync   = 1;
+    in[1].before = EXT_STOP;
+    in[1].after  = EXT_STOP;
+    s->fs.opaque   = s;
+    s->fs.on_event = process_frame;
+
+    return ff_framesync_configure(&s->fs);
+}
+
+static int activate(AVFilterContext *ctx)
+{
+    VIFContext *s = ctx->priv;
+    return ff_framesync_activate(&s->fs);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    VIFContext *s = ctx->priv;
+
+    if (s->nb_frames > 0) {
+        for (int i = 0; i < 4; i++)
+            av_log(ctx, AV_LOG_INFO, "VIF scale=%d average:%f min:%f: max:%f\n",
+                   i, s->vif_sum[i] / s->nb_frames, s->vif_min[i], s->vif_max[i]);
+    }
+
+    for (int i = 0; i < 13; i++)
+        av_freep(&s->data_buf[i]);
+
+    av_freep(&s->ref_data);
+    av_freep(&s->main_data);
+
+    for (int i = 0; i < s->nb_threads && s->temp; i++)
+        av_freep(&s->temp[i]);
+
+    av_freep(&s->temp);
+
+    ff_framesync_uninit(&s->fs);
+}
+
+static const AVFilterPad vif_inputs[] = {
+    {
+        .name         = "main",
+        .type         = AVMEDIA_TYPE_VIDEO,
+    },{
+        .name         = "reference",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input_ref,
+    },
+    { NULL }
+};
+
+static const AVFilterPad vif_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = config_output,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_vif = {
+    .name          = "vif",
+    .description   = NULL_IF_CONFIG_SMALL("Calculate the VIF between two video streams."),
+    .uninit        = uninit,
+    .query_formats = query_formats,
+    .priv_size     = sizeof(VIFContext),
+    .priv_class    = &vif_class,
+    .activate      = activate,
+    .inputs        = vif_inputs,
+    .outputs       = vif_outputs,
+    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL | AVFILTER_FLAG_SLICE_THREADS,
+};
diff --git a/libavfilter/vif.h b/libavfilter/vif.h
new file mode 100644
index 0000000000..040c709c6a
--- /dev/null
+++ b/libavfilter/vif.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2017 Ronald S. Bultje <rsbultje@gmail.com>
+ * Copyright (c) 2017 Ashish Pratap Singh <ashk43712@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
+ */
+
+#ifndef AVFILTER_VIF_H
+#define AVFILTER_VIF_H
+
+int ff_compute_vif2(AVFilterContext *ctx,
+                    const float *ref, const float *main, int w, int h,
+                    int ref_stride, int main_stride, float *score,
+                    float *data_buf[13], float **temp, int nb_threads);
+
+#endif /* AVFILTER_VIF_H */