avfilter: add ssim filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Changelog

@@ -7,6 +7,7 @@ version <next>:
 - little-endian ADPCM_THP decoder
 - Hap decoder and encoder
 - DirectDraw Surface image/texture decoder
+- ssim filter
 
 
 version 2.7:

doc/filters.texi

@@ -8834,6 +8834,64 @@ in [-30,0] will filter edges. Default value is 0.
 If a chroma option is not explicitly set, the corresponding luma value
 is set.
 
+@section ssim
+
+Obtain the SSIM (Structural SImilarity Metric) between two input videos.
+
+This filter takes in input two input videos, the first input is
+considered the "main" source and is passed unchanged to the
+output. The second input is used as a "reference" video for computing
+the SSIM.
+
+Both video inputs 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 filter stores the calculated SSIM of each frame.
+
+The description of the accepted parameters follows.
+
+@table @option
+@item stats_file, f
+If specified the filter will use the named file to save the PSNR of
+each individual frame.
+@end table
+
+The file printed if @var{stats_file} is selected, contains a sequence of
+key/value pairs of the form @var{key}:@var{value} for each compared
+couple of frames.
+
+A description of each shown parameter follows:
+
+@table @option
+@item n
+sequential number of the input frame, starting from 1
+
+@item Y, U, V, R, G, B
+SSIM of the compared frames for the component specified by the suffix.
+
+@item All
+SSIM of the compared frames for the whole frame.
+
+@item dB
+Same as above but in dB representation.
+@end table
+
+For example:
+@example
+movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
+[main][ref] ssim="stats_file=stats.log" [out]
+@end example
+
+On this example the input file being processed is compared with the
+reference file @file{ref_movie.mpg}. The SSIM of each individual frame
+is stored in @file{stats.log}.
+
+Another example with both psnr and ssim at same time:
+@example
+ffmpeg -i main.mpg -i ref.mpg -lavfi  "ssim;[0:v][1:v]psnr" -f null -
+@end example
+
 @section stereo3d
 
 Convert between different stereoscopic image formats.

libavfilter/Makefile

@@ -197,6 +197,7 @@ OBJS-$(CONFIG_SIGNALSTATS_FILTER)            += vf_signalstats.o
 OBJS-$(CONFIG_SMARTBLUR_FILTER)              += vf_smartblur.o
 OBJS-$(CONFIG_SPLIT_FILTER)                  += split.o
 OBJS-$(CONFIG_SPP_FILTER)                    += vf_spp.o
+OBJS-$(CONFIG_SSIM_FILTER)                   += vf_ssim.o dualinput.o framesync.o
 OBJS-$(CONFIG_STEREO3D_FILTER)               += vf_stereo3d.o
 OBJS-$(CONFIG_SUBTITLES_FILTER)              += vf_subtitles.o
 OBJS-$(CONFIG_SUPER2XSAI_FILTER)             += vf_super2xsai.o

libavfilter/allfilters.c

@@ -212,6 +212,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(SMARTBLUR,      smartblur,      vf);
     REGISTER_FILTER(SPLIT,          split,          vf);
     REGISTER_FILTER(SPP,            spp,            vf);
+    REGISTER_FILTER(SSIM,           ssim,           vf);
     REGISTER_FILTER(STEREO3D,       stereo3d,       vf);
     REGISTER_FILTER(SUBTITLES,      subtitles,      vf);
     REGISTER_FILTER(SUPER2XSAI,     super2xsai,     vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  5
-#define LIBAVFILTER_VERSION_MINOR  17
+#define LIBAVFILTER_VERSION_MINOR  18
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vf_ssim.c

+/*
+ * Copyright (c) 2003-2013 Loren Merritt
+ * Copyright (c) 2015 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
+ */
+
+/* Computes the Structural Similarity Metric between two video streams.
+ * original algorithm:
+ * Z. Wang, A. C. Bovik, H. R. Sheikh and E. P. Simoncelli,
+ *   "Image quality assessment: From error visibility to structural similarity,"
+ *   IEEE Transactions on Image Processing, vol. 13, no. 4, pp. 600-612, Apr. 2004.
+ *
+ * To improve speed, this implementation uses the standard approximation of
+ * overlapped 8x8 block sums, rather than the original gaussian weights.
+ */
+
+/*
+ * @file
+ * Caculate the SSIM between two input videos.
+ */
+
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "avfilter.h"
+#include "dualinput.h"
+#include "drawutils.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct SSIMContext {
+    const AVClass *class;
+    FFDualInputContext dinput;
+    FILE *stats_file;
+    char *stats_file_str;
+    int nb_components;
+    uint64_t nb_frames;
+    double ssim[4];
+    char comps[4];
+    int *coefs;
+    uint8_t rgba_map[4];
+    int planewidth[4];
+    int planeheight[4];
+    int *temp;
+} SSIMContext;
+
+#define OFFSET(x) offsetof(SSIMContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+
+static const AVOption ssim_options[] = {
+    {"stats_file", "Set file where to store per-frame difference information", OFFSET(stats_file_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
+    {"f",          "Set file where to store per-frame difference information", OFFSET(stats_file_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(ssim);
+
+static int rgb_coefs[4]  = { 1, 1, 1, 3};
+static int yuv_coefs[4]  = { 4, 1, 1, 6};
+static int gray_coefs[4] = { 1, 0, 0, 1};
+
+static void set_meta(AVDictionary **metadata, const char *key, char comp, float d)
+{
+    char value[128];
+    snprintf(value, sizeof(value), "%0.2f", d);
+    if (comp) {
+        char key2[128];
+        snprintf(key2, sizeof(key2), "%s%c", key, comp);
+        av_dict_set(metadata, key2, value, 0);
+    } else {
+        av_dict_set(metadata, key, value, 0);
+    }
+}
+
+static void ssim_4x4x2_core(const uint8_t *main, int main_stride,
+                            const uint8_t *ref, int ref_stride,
+                            int sums[2][4])
+{
+    int x, y, z;
+
+    for (z = 0; z < 2; z++) {
+        uint32_t s1 = 0, s2 = 0, ss = 0, s12 = 0;
+
+        for (y = 0; y < 4; y++) {
+            for (x = 0; x < 4; x++) {
+                int a = main[x + y * main_stride];
+                int b = ref[x + y * ref_stride];
+
+                s1  += a;
+                s2  += b;
+                ss  += a*a;
+                ss  += b*b;
+                s12 += a*b;
+            }
+        }
+
+        sums[z][0] = s1;
+        sums[z][1] = s2;
+        sums[z][2] = ss;
+        sums[z][3] = s12;
+        main += 4;
+        ref += 4;
+    }
+}
+
+static float ssim_end1(int s1, int s2, int ss, int s12)
+{
+    static const int ssim_c1 = (int)(.01*.01*255*255*64 + .5);
+    static const int ssim_c2 = (int)(.03*.03*255*255*64*63 + .5);
+
+    int fs1 = s1;
+    int fs2 = s2;
+    int fss = ss;
+    int fs12 = s12;
+    int vars = fss * 64 - fs1 * fs1 - fs2 * fs2;
+    int covar = fs12 * 64 - fs1 * fs2;
+
+    return (float)(2 * fs1 * fs2 + ssim_c1) * (float)(2 * covar + ssim_c2)
+         / ((float)(fs1 * fs1 + fs2 * fs2 + ssim_c1) * (float)(vars + ssim_c2));
+}
+
+static float ssim_end4(int sum0[5][4], int sum1[5][4], int width)
+{
+    float ssim = 0.0;
+    int i;
+
+    for( i = 0; i < width; i++ )
+        ssim += ssim_end1(sum0[i][0] + sum0[i + 1][0] + sum1[i][0] + sum1[i + 1][0],
+                          sum0[i][1] + sum0[i + 1][1] + sum1[i][1] + sum1[i + 1][1],
+                          sum0[i][2] + sum0[i + 1][2] + sum1[i][2] + sum1[i + 1][2],
+                          sum0[i][3] + sum0[i + 1][3] + sum1[i][3] + sum1[i + 1][3]);
+    return ssim;
+}
+
+static float ssim_plane(uint8_t *main, int main_stride,
+                        uint8_t *ref, int ref_stride,
+                        int width, int height, void *temp)
+{
+    int z = 0;
+    int x, y;
+    float ssim = 0.0;
+    int (*sum0)[4] = temp;
+    int (*sum1)[4] = sum0 + (width >> 2) + 3;
+
+    width >>= 2;
+    height >>= 2;
+
+    for (y = 1; y < height; y++) {
+        for (; z <= y; z++) {
+            FFSWAP(void*, sum0, sum1);
+            for (x = 0; x < width; x+=2)
+                ssim_4x4x2_core(&main[4 * (x + z * main_stride)], main_stride,
+                                &ref[4 * (x + z * ref_stride)], ref_stride,
+                                &sum0[x]);
+        }
+
+        for (x = 0; x < width - 1; x += 4)
+            ssim += ssim_end4(sum0 + x, sum1 + x, FFMIN(4, width - x - 1));
+    }
+
+    return ssim / ((height - 1) * (width - 1));
+}
+
+static double ssim_db(double ssim, double weight)
+{
+    return 10 * (log(weight) / log(10) - log(weight - ssim) / log(10));
+}
+
+static AVFrame *do_ssim(AVFilterContext *ctx, AVFrame *main,
+                        const AVFrame *ref)
+{
+    AVDictionary **metadata = avpriv_frame_get_metadatap(main);
+    SSIMContext *s = ctx->priv;
+    float c[4], ssimv;
+    int i;
+
+    s->nb_frames++;
+
+    for (i = 0; i < s->nb_components; i++)
+        c[i] = ssim_plane(main->data[i], main->linesize[i],
+                          ref->data[i], ref->linesize[i],
+                          s->planewidth[i], s->planeheight[i], s->temp);
+
+    ssimv = (c[0] * s->coefs[0] + c[1] * s->coefs[1] + c[2] * s->coefs[2]) / s->coefs[3];
+
+    for (i = 0; i < s->nb_components; i++)
+        set_meta(metadata, "lavfi.ssim.", s->comps[i], c[i]);
+
+    set_meta(metadata, "lavfi.ssim.All", 0, ssimv);
+    set_meta(metadata, "lavfi.ssim.dB", 0, ssim_db(c[0] * s->coefs[0] + c[1] * s->coefs[1] + c[2] * s->coefs[2], s->coefs[3]));
+
+    if (s->stats_file) {
+        fprintf(s->stats_file, "n:%"PRId64" ", s->nb_frames);
+
+        for (i = 0; i < s->nb_components; i++)
+            fprintf(s->stats_file, "%c:%f ", s->comps[i], c[i]);
+
+        fprintf(s->stats_file, "All:%f (%f)\n", ssimv, ssim_db(c[0] * s->coefs[0] + c[1] * s->coefs[1] + c[2] * s->coefs[2], s->coefs[3]));
+    }
+
+    s->ssim[0] += c[0];
+    s->ssim[1] += c[1];
+    s->ssim[2] += c[2];
+
+    return main;
+}
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    SSIMContext *s = ctx->priv;
+
+    if (s->stats_file_str) {
+        s->stats_file = fopen(s->stats_file_str, "w");
+        if (!s->stats_file) {
+            int err = AVERROR(errno);
+            char buf[128];
+            av_strerror(err, buf, sizeof(buf));
+            av_log(ctx, AV_LOG_ERROR, "Could not open stats file %s: %s\n",
+                   s->stats_file_str, buf);
+            return err;
+        }
+    }
+
+    s->dinput.process = do_ssim;
+    s->dinput.shortest = 1;
+    s->dinput.repeatlast = 0;
+    return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum AVPixelFormat pix_fmts[] = {
+        AV_PIX_FMT_GRAY8,
+        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV444P,
+        AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
+        AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
+        AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
+        AV_PIX_FMT_GBRP,
+        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)
+{
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
+    AVFilterContext *ctx  = inlink->dst;
+    SSIMContext *s = ctx->priv;
+    int is_rgb;
+
+    s->nb_components = desc->nb_components;
+
+    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);
+    }
+
+    is_rgb = ff_fill_rgba_map(s->rgba_map, inlink->format) >= 0;
+    s->comps[0] = is_rgb ? 'R' : 'Y';
+    s->comps[1] = is_rgb ? 'G' : 'U';
+    s->comps[2] = is_rgb ? 'B' : 'V';
+    s->comps[3] = 'A';
+
+    if (is_rgb) {
+        s->coefs = rgb_coefs;
+    } else if (s->nb_components == 1) {
+        s->coefs = gray_coefs;
+    } else {
+        s->coefs = yuv_coefs;
+    }
+
+    s->planeheight[1] = s->planeheight[2] = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
+    s->planeheight[0] = s->planeheight[3] = inlink->h;
+    s->planewidth[1]  = s->planewidth[2]  = FF_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);
+    s->planewidth[0]  = s->planewidth[3]  = inlink->w;
+
+    s->temp = av_malloc((2 * inlink->w + 12) * sizeof(*s->temp));
+    if (!s->temp)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    SSIMContext *s = ctx->priv;
+    AVFilterLink *mainlink = ctx->inputs[0];
+    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_dualinput_init(ctx, &s->dinput)) < 0)
+        return ret;
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
+{
+    SSIMContext *s = inlink->dst->priv;
+    return ff_dualinput_filter_frame(&s->dinput, inlink, buf);
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    SSIMContext *s = outlink->src->priv;
+    return ff_dualinput_request_frame(&s->dinput, outlink);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    SSIMContext *s = ctx->priv;
+
+    if (s->nb_frames > 0) {
+        if (s->nb_components == 3) {
+            av_log(ctx, AV_LOG_INFO, "SSIM %c:%f %c:%f %c:%f All:%f (%f)\n",
+               s->comps[0], s->ssim[0] / s->nb_frames,
+               s->comps[1], s->ssim[1] / s->nb_frames,
+               s->comps[2], s->ssim[2] / s->nb_frames,
+               (s->ssim[0] * 4 + s->ssim[1] + s->ssim[2]) / (s->nb_frames * 6),
+               ssim_db(s->ssim[0] * 4 + s->ssim[1] + s->ssim[2], s->nb_frames * 6));
+        } else if (s->nb_components == 1) {
+            av_log(ctx, AV_LOG_INFO, "SSIM All:%f (%f)\n",
+               s->ssim[0] / s->nb_frames, ssim_db(s->ssim[0], s->nb_frames));
+        }
+    }
+
+    ff_dualinput_uninit(&s->dinput);
+
+    if (s->stats_file)
+        fclose(s->stats_file);
+
+    av_freep(&s->temp);
+}
+
+static const AVFilterPad ssim_inputs[] = {
+    {
+        .name         = "main",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+    },{
+        .name         = "reference",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+        .config_props = config_input_ref,
+    },
+    { NULL }
+};
+
+static const AVFilterPad ssim_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = config_output,
+        .request_frame = request_frame,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_ssim = {
+    .name          = "ssim",
+    .description   = NULL_IF_CONFIG_SMALL("Calculate the SSIM between two video streams."),
+    .init          = init,
+    .uninit        = uninit,
+    .query_formats = query_formats,
+    .priv_size     = sizeof(SSIMContext),
+    .priv_class    = &ssim_class,
+    .inputs        = ssim_inputs,
+    .outputs       = ssim_outputs,
+};