ref: 3b35e962e281b8e604b77d533b4c7b0498cb4748
parent: 931c0a954f659cf0210a6abde660e466c01b91e5
parent: ee87e20d53d16bcf7971468079c0ae0d63e41c44
author: Jim Bankoski <[email protected]>
date: Tue Apr 21 12:11:11 EDT 2015
Merge "Adds a new temporal consistency metric to libvpx."
--- /dev/null
+++ b/test/consistency_test.cc
@@ -1,0 +1,224 @@
+/*
+ * Copyright (c) 2012 The WebM project authors. All Rights Reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+
+#include <string.h>
+#include <limits.h>
+#include <stdio.h>
+
+#include "./vpx_config.h"
+#if CONFIG_VP9_ENCODER
+#include "./vp9_rtcd.h"
+#endif
+
+#include "test/acm_random.h"
+#include "test/clear_system_state.h"
+#include "test/register_state_check.h"
+#include "test/util.h"
+#include "third_party/googletest/src/include/gtest/gtest.h"
+#include "vp9/encoder/vp9_ssim.h"
+#include "vpx_mem/vpx_mem.h"
+
+extern "C"
+double vp9_get_ssim_metrics(uint8_t *img1, int img1_pitch,
+ uint8_t *img2, int img2_pitch,
+ int width, int height,
+ Ssimv *sv2, Metrics *m,
+ int do_inconsistency);
+
+using libvpx_test::ACMRandom;
+
+namespace {+class ConsistencyTestBase : public ::testing::Test {+ public:
+ ConsistencyTestBase(int width, int height) : width_(width), height_(height) {}+
+ static void SetUpTestCase() {+ source_data_[0] = reinterpret_cast<uint8_t*>(
+ vpx_memalign(kDataAlignment, kDataBufferSize));
+ reference_data_[0] = reinterpret_cast<uint8_t*>(
+ vpx_memalign(kDataAlignment, kDataBufferSize));
+ source_data_[1] = reinterpret_cast<uint8_t*>(
+ vpx_memalign(kDataAlignment, kDataBufferSize));
+ reference_data_[1] = reinterpret_cast<uint8_t*>(
+ vpx_memalign(kDataAlignment, kDataBufferSize));
+ ssim_array_ = new Ssimv[kDataBufferSize / 16];
+ }
+
+ static void ClearSsim() {+ memset(ssim_array_, 0, kDataBufferSize / 16);
+ }
+ static void TearDownTestCase() {+ vpx_free(source_data_[0]);
+ source_data_[0] = NULL;
+ vpx_free(reference_data_[0]);
+ reference_data_[0] = NULL;
+ vpx_free(source_data_[1]);
+ source_data_[1] = NULL;
+ vpx_free(reference_data_[1]);
+ reference_data_[1] = NULL;
+
+ delete ssim_array_;
+ }
+
+ virtual void TearDown() {+ libvpx_test::ClearSystemState();
+ }
+
+ protected:
+ // Handle frames up to 640x480
+ static const int kDataAlignment = 16;
+ static const int kDataBufferSize = 640*480;
+
+ virtual void SetUp() {+ source_stride_ = (width_ + 31) & ~31;
+ reference_stride_ = width_ * 2;
+ rnd_.Reset(ACMRandom::DeterministicSeed());
+ }
+
+ void FillRandom(uint8_t *data, int stride, int width, int height) {+ for (int h = 0; h < height; ++h) {+ for (int w = 0; w < width; ++w) {+ data[h * stride + w] = rnd_.Rand8();
+ }
+ }
+ }
+
+ void FillRandom(uint8_t *data, int stride) {+ FillRandom(data, stride, width_, height_);
+ }
+
+ void Copy(uint8_t *reference, uint8_t *source) {+ memcpy(reference, source, kDataBufferSize);
+ }
+
+ void Blur(uint8_t *data, int stride, int taps) {+ int sum = 0;
+ int half_taps = taps / 2;
+ for (int h = 0; h < height_; ++h) {+ for (int w = 0; w < taps; ++w) {+ sum += data[w + h * stride];
+ }
+ for (int w = taps; w < width_; ++w) {+ sum += data[w + h * stride] - data[w - taps + h * stride];
+ data[w - half_taps + h * stride] = (sum + half_taps) / taps;
+ }
+ }
+ for (int w = 0; w < width_; ++w) {+ for (int h = 0; h < taps; ++h) {+ sum += data[h + w * stride];
+ }
+ for (int h = taps; h < height_; ++h) {+ sum += data[w + h * stride] - data[(h - taps) * stride + w];
+ data[(h - half_taps) * stride + w] = (sum + half_taps) / taps;
+ }
+ }
+ }
+ int width_, height_;
+ static uint8_t* source_data_[2];
+ int source_stride_;
+ static uint8_t* reference_data_[2];
+ int reference_stride_;
+ static Ssimv *ssim_array_;
+ Metrics metrics_;
+
+ ACMRandom rnd_;
+};
+
+#if CONFIG_VP9_ENCODER
+typedef std::tr1::tuple<int, int> ConsistencyParam;
+class ConsistencyVP9Test
+ : public ConsistencyTestBase,
+ public ::testing::WithParamInterface<ConsistencyParam> {+ public:
+ ConsistencyVP9Test() : ConsistencyTestBase(GET_PARAM(0), GET_PARAM(1)) {}+
+ protected:
+ double CheckConsistency(int frame) {+ EXPECT_LT(frame, 2)<< "Frame to check has to be less than 2.";
+ return
+ vp9_get_ssim_metrics(source_data_[frame], source_stride_,
+ reference_data_[frame], reference_stride_,
+ width_, height_, ssim_array_, &metrics_, 1);
+ }
+};
+#endif // CONFIG_VP9_ENCODER
+
+uint8_t* ConsistencyTestBase::source_data_[2] = {NULL, NULL};+uint8_t* ConsistencyTestBase::reference_data_[2] = {NULL, NULL};+Ssimv* ConsistencyTestBase::ssim_array_ = NULL;
+
+#if CONFIG_VP9_ENCODER
+TEST_P(ConsistencyVP9Test, ConsistencyIsZero) {+ FillRandom(source_data_[0], source_stride_);
+ Copy(source_data_[1], source_data_[0]);
+ Copy(reference_data_[0], source_data_[0]);
+ Blur(reference_data_[0], reference_stride_, 3);
+ Copy(reference_data_[1], source_data_[0]);
+ Blur(reference_data_[1], reference_stride_, 3);
+
+ double inconsistency = CheckConsistency(1);
+ inconsistency = CheckConsistency(0);
+ EXPECT_EQ(inconsistency, 0.0)
+ << "Should have 0 inconsistency if they are exactly the same.";
+
+ // If sources are not consistent reference frames inconsistency should
+ // be less than if the source is consistent.
+ FillRandom(source_data_[0], source_stride_);
+ FillRandom(source_data_[1], source_stride_);
+ FillRandom(reference_data_[0], reference_stride_);
+ FillRandom(reference_data_[1], reference_stride_);
+ CheckConsistency(0);
+ inconsistency = CheckConsistency(1);
+
+ Copy(source_data_[1], source_data_[0]);
+ CheckConsistency(0);
+ double inconsistency2 = CheckConsistency(1);
+ EXPECT_LT(inconsistency, inconsistency2)
+ << "Should have less inconsistency if source itself is inconsistent.";
+
+ // Less of a blur should be less inconsistent than more blur coming off a
+ // a frame with no blur.
+ ClearSsim();
+ FillRandom(source_data_[0], source_stride_);
+ Copy(source_data_[1], source_data_[0]);
+ Copy(reference_data_[0], source_data_[0]);
+ Copy(reference_data_[1], source_data_[0]);
+ Blur(reference_data_[1], reference_stride_, 4);
+ CheckConsistency(0);
+ inconsistency = CheckConsistency(1);
+ ClearSsim();
+ Copy(reference_data_[1], source_data_[0]);
+ Blur(reference_data_[1], reference_stride_, 8);
+ CheckConsistency(0);
+ inconsistency2 = CheckConsistency(1);
+
+ EXPECT_LT(inconsistency, inconsistency2)
+ << "Stronger Blur should produce more inconsistency.";
+}
+#endif // CONFIG_VP9_ENCODER
+
+
+using std::tr1::make_tuple;
+
+//------------------------------------------------------------------------------
+// C functions
+
+#if CONFIG_VP9_ENCODER
+const ConsistencyParam c_vp9_tests[] = {+ make_tuple(320, 240),
+ make_tuple(318, 242),
+ make_tuple(318, 238),
+};
+INSTANTIATE_TEST_CASE_P(C, ConsistencyVP9Test,
+ ::testing::ValuesIn(c_vp9_tests));
+#endif
+
+} // namespace
--- a/test/test.mk
+++ b/test/test.mk
@@ -151,6 +151,8 @@
ifeq ($(CONFIG_VP9_ENCODER),yes)
LIBVPX_TEST_SRCS-$(CONFIG_SPATIAL_SVC) += svc_test.cc
LIBVPX_TEST_SRCS-$(CONFIG_INTERNAL_STATS) += blockiness_test.cc
+LIBVPX_TEST_SRCS-$(CONFIG_INTERNAL_STATS) += consistency_test.cc
+
endif
ifeq ($(CONFIG_VP9_ENCODER)$(CONFIG_VP9_TEMPORAL_DENOISING),yesyes)
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -1642,8 +1642,9 @@
#if CONFIG_INTERNAL_STATS
cpi->b_calculate_ssimg = 0;
cpi->b_calculate_blockiness = 1;
+ cpi->b_calculate_consistency = 1;
+ cpi->total_inconsistency = 0;
-
cpi->count = 0;
cpi->bytes = 0;
@@ -1693,6 +1694,10 @@
cpi->total_blockiness = 0;
}
+ if (cpi->b_calculate_consistency) {+ cpi->ssim_vars = vpx_malloc(sizeof(*cpi->ssim_vars)*720*480);
+ }
+
#endif
cpi->first_time_stamp_ever = INT64_MAX;
@@ -1889,7 +1894,13 @@
return cpi;
}
+#define SNPRINT(H, T) \
+ snprintf((H) + strlen(H), sizeof(H) - strlen(H), (T))
+#define SNPRINT2(H, T, V) \
+ snprintf((H) + strlen(H), sizeof(H) - strlen(H), (T), (V))
+
+
void vp9_remove_compressor(VP9_COMP *cpi) {VP9_COMMON *const cm = &cpi->common;
unsigned int i;
@@ -1902,8 +1913,9 @@
#if CONFIG_INTERNAL_STATS
vp9_clear_system_state();
- // printf("\n8x8-4x4:%d-%d\n", cpi->t8x8_count, cpi->t4x4_count); if (cpi->oxcf.pass != 1) {+ char headings[512] = {0};+ char results[512] = {0}; FILE *f = fopen("opsnr.stt", "a");double time_encoded = (cpi->last_end_time_stamp_seen
- cpi->first_time_stamp_ever) / 10000000.000;
@@ -1921,39 +1933,39 @@
vpx_sse_to_psnr((double)cpi->totalp_samples, peak,
(double)cpi->totalp_sq_error);
const double total_ssim = 100 * pow(cpi->summed_quality /
- cpi->summed_weights, 8.0);
+ cpi->summed_weights, 8.0);
+
+ snprintf(headings, sizeof(headings),
+ "Bitrate\tAVGPsnr\tGLBPsnr\tAVPsnrP\tGLPsnrP\t"
+ "VPXSSIM\tFASTSIM\tPSNRHVS");
+ snprintf(results, sizeof(results),
+ "%7.2f\t%7.3f\t%7.3f\t%7.3f\t%7.3f\t"
+ "%7.3f\t%7.3f\t%7.3f", dr,
+ cpi->total / cpi->count, total_psnr,
+ cpi->totalp / cpi->count, totalp_psnr, total_ssim,
+ cpi->total_fastssim_all / cpi->count,
+ cpi->total_psnrhvs_all / cpi->count);
if (cpi->b_calculate_blockiness) {- fprintf(f, "Bitrate\tAVGPsnr\tGLBPsnr\tAVPsnrP\tGLPsnrP\t"
- "VPXSSIM\tVPSSIMP\tFASTSSIM\tPSNRHVS\tTime(ms)\n");
- fprintf(f, "%7.2f\t%7.3f\t%7.3f\t%7.3f\t%7.3f\t%7.3f\t"
- "%7.3f\t%7.3f\t%8.0f\n",
- dr, cpi->total / cpi->count, total_psnr,
- cpi->totalp / cpi->count, totalp_psnr, total_ssim,
- cpi->total_fastssim_all / cpi->count,
- cpi->total_psnrhvs_all / cpi->count,
- total_encode_time);
- } else {- fprintf(f, "Bitrate\tAVGPsnr\tGLBPsnr\tAVPsnrP\tGLPsnrP\t"
- "VPXSSIM\tVPSSIMP\tBlockiness\tFASTSSIM\tPSNRHVS\tTime(ms)\n");
- fprintf(f, "%7.2f\t%7.3f\t%7.3f\t%7.3f\t%7.3f\t%7.3f\t"
- "%7.3f\t%7.3f\t%7.3f\t%8.0f\n",
- dr, cpi->total / cpi->count, total_psnr,
- cpi->totalp / cpi->count, totalp_psnr, total_ssim,
- cpi->total_blockiness / cpi->count,
- cpi->total_fastssim_all / cpi->count,
- cpi->total_psnrhvs_all / cpi->count,
- total_encode_time);
+ SNPRINT(headings, "\t Block");
+ SNPRINT2(results, "\t%7.3f", cpi->total_blockiness / cpi->count);
}
- }
+ if (cpi->b_calculate_consistency) {+ double consistency =
+ vpx_sse_to_psnr((double)cpi->totalp_samples, peak,
+ (double)cpi->total_inconsistency);
- if (cpi->b_calculate_ssimg) {- fprintf(f, "BitRate\tSSIM_Y\tSSIM_U\tSSIM_V\tSSIM_A\t Time(ms)\n");
- fprintf(f, "%7.2f\t%6.4f\t%6.4f\t%6.4f\t%6.4f\t%8.0f\n", dr,
- cpi->total_ssimg_y / cpi->count,
- cpi->total_ssimg_u / cpi->count,
- cpi->total_ssimg_v / cpi->count,
- cpi->total_ssimg_all / cpi->count, total_encode_time);
+ SNPRINT(headings, "\tConsist");
+ SNPRINT2(results, "\t%7.3f", consistency);
+ }
+
+ if (cpi->b_calculate_ssimg) {+ SNPRINT(headings, "\t SSIMG");
+ SNPRINT2(results, "\t%7.3f", cpi->total_ssimg_all / cpi->count);
+ }
+
+ fprintf(f, "%s\t Time\n", headings);
+ fprintf(f, "%s\t%8.0f\n", results, total_encode_time);
}
fclose(f);
@@ -4224,6 +4236,16 @@
cm->frame_to_show->y_buffer,
cm->frame_to_show->y_stride,
cpi->Source->y_width, cpi->Source->y_height);
+
+ if (cpi->b_calculate_consistency)
+ cpi->total_inconsistency += vp9_get_ssim_metrics(cpi->Source->y_buffer,
+ cpi->Source->y_stride,
+ cm->frame_to_show->y_buffer,
+ cm->frame_to_show->y_stride,
+ cpi->Source->y_width,
+ cpi->Source->y_height,
+ cpi->ssim_vars,
+ &cpi->metrics, 1);
if (cpi->b_calculate_ssimg) {double y, u, v, frame_all;
--- a/vp9/encoder/vp9_encoder.h
+++ b/vp9/encoder/vp9_encoder.h
@@ -34,6 +34,9 @@
#include "vp9/encoder/vp9_quantize.h"
#include "vp9/encoder/vp9_ratectrl.h"
#include "vp9/encoder/vp9_rd.h"
+#if CONFIG_INTERNAL_STATS
+#include "vp9/encoder/vp9_ssim.h"
+#endif
#include "vp9/encoder/vp9_speed_features.h"
#include "vp9/encoder/vp9_svc_layercontext.h"
#include "vp9/encoder/vp9_tokenize.h"
@@ -429,6 +432,10 @@
int b_calculate_ssimg;
int b_calculate_blockiness;
+ int b_calculate_consistency;
+ double total_inconsistency;
+ Ssimv *ssim_vars;
+ Metrics metrics;
#endif
int b_calculate_psnr;
--- a/vp9/encoder/vp9_ssim.c
+++ b/vp9/encoder/vp9_ssim.c
@@ -8,8 +8,8 @@
* be found in the AUTHORS file in the root of the source tree.
*/
+#include <math.h>
#include "./vp9_rtcd.h"
-
#include "vp9/encoder/vp9_ssim.h"
void vp9_ssim_parms_16x16_c(uint8_t *s, int sp, uint8_t *r,
@@ -200,6 +200,251 @@
return ssim_all;
}
+
+// traditional ssim as per: http://en.wikipedia.org/wiki/Structural_similarity
+//
+// Re working out the math ->
+//
+// ssim(x,y) = (2*mean(x)*mean(y) + c1)*(2*cov(x,y)+c2) /
+// ((mean(x)^2+mean(y)^2+c1)*(var(x)+var(y)+c2))
+//
+// mean(x) = sum(x) / n
+//
+// cov(x,y) = (n*sum(xi*yi)-sum(x)*sum(y))/(n*n)
+//
+// var(x) = (n*sum(xi*xi)-sum(xi)*sum(xi))/(n*n)
+//
+// ssim(x,y) =
+// (2*sum(x)*sum(y)/(n*n) + c1)*(2*(n*sum(xi*yi)-sum(x)*sum(y))/(n*n)+c2) /
+// (((sum(x)*sum(x)+sum(y)*sum(y))/(n*n) +c1) *
+// ((n*sum(xi*xi) - sum(xi)*sum(xi))/(n*n)+
+// (n*sum(yi*yi) - sum(yi)*sum(yi))/(n*n)+c2)))
+//
+// factoring out n*n
+//
+// ssim(x,y) =
+// (2*sum(x)*sum(y) + n*n*c1)*(2*(n*sum(xi*yi)-sum(x)*sum(y))+n*n*c2) /
+// (((sum(x)*sum(x)+sum(y)*sum(y)) + n*n*c1) *
+// (n*sum(xi*xi)-sum(xi)*sum(xi)+n*sum(yi*yi)-sum(yi)*sum(yi)+n*n*c2))
+//
+// Replace c1 with n*n * c1 for the final step that leads to this code:
+// The final step scales by 12 bits so we don't lose precision in the constants.
+
+double ssimv_similarity(Ssimv *sv, int64_t n) {+ // Scale the constants by number of pixels.
+ const int64_t c1 = (cc1 * n * n) >> 12;
+ const int64_t c2 = (cc2 * n * n) >> 12;
+
+ const double l = 1.0 * (2 * sv->sum_s * sv->sum_r + c1) /
+ (sv->sum_s * sv->sum_s + sv->sum_r * sv->sum_r + c1);
+
+ // Since these variables are unsigned sums, convert to double so
+ // math is done in double arithmetic.
+ const double v = (2.0 * n * sv->sum_sxr - 2 * sv->sum_s * sv->sum_r + c2)
+ / (n * sv->sum_sq_s - sv->sum_s * sv->sum_s + n * sv->sum_sq_r
+ - sv->sum_r * sv->sum_r + c2);
+
+ return l * v;
+}
+
+// The first term of the ssim metric is a luminance factor.
+//
+// (2*mean(x)*mean(y) + c1)/ (mean(x)^2+mean(y)^2+c1)
+//
+// This luminance factor is super sensitive to the dark side of luminance
+// values and completely insensitive on the white side. check out 2 sets
+// (1,3) and (250,252) the term gives ( 2*1*3/(1+9) = .60
+// 2*250*252/ (250^2+252^2) => .99999997
+//
+// As a result in this tweaked version of the calculation in which the
+// luminance is taken as percentage off from peak possible.
+//
+// 255 * 255 - (sum_s - sum_r) / count * (sum_s - sum_r) / count
+//
+double ssimv_similarity2(Ssimv *sv, int64_t n) {+ // Scale the constants by number of pixels.
+ const int64_t c1 = (cc1 * n * n) >> 12;
+ const int64_t c2 = (cc2 * n * n) >> 12;
+
+ const double mean_diff = (1.0 * sv->sum_s - sv->sum_r) / n;
+ const double l = (255 * 255 - mean_diff * mean_diff + c1) / (255 * 255 + c1);
+
+ // Since these variables are unsigned, sums convert to double so
+ // math is done in double arithmetic.
+ const double v = (2.0 * n * sv->sum_sxr - 2 * sv->sum_s * sv->sum_r + c2)
+ / (n * sv->sum_sq_s - sv->sum_s * sv->sum_s +
+ n * sv->sum_sq_r - sv->sum_r * sv->sum_r + c2);
+
+ return l * v;
+}
+void ssimv_parms(uint8_t *img1, int img1_pitch, uint8_t *img2, int img2_pitch,
+ Ssimv *sv) {+ vp9_ssim_parms_8x8(img1, img1_pitch, img2, img2_pitch,
+ &sv->sum_s, &sv->sum_r, &sv->sum_sq_s, &sv->sum_sq_r,
+ &sv->sum_sxr);
+}
+
+double vp9_get_ssim_metrics(uint8_t *img1, int img1_pitch,
+ uint8_t *img2, int img2_pitch,
+ int width, int height,
+ Ssimv *sv2, Metrics *m,
+ int do_inconsistency) {+ double dssim_total = 0;
+ double ssim_total = 0;
+ double ssim2_total = 0;
+ double inconsistency_total = 0;
+ int i, j;
+ int c = 0;
+ double norm;
+ double old_ssim_total = 0;
+ vp9_clear_system_state();
+ // We can sample points as frequently as we like start with 1 per 4x4.
+ for (i = 0; i < height; i += 4,
+ img1 += img1_pitch * 4, img2 += img2_pitch * 4) {+ for (j = 0; j < width; j += 4, ++c) {+ Ssimv sv = {0};+ double ssim;
+ double ssim2;
+ double dssim;
+ uint32_t var_new;
+ uint32_t var_old;
+ uint32_t mean_new;
+ uint32_t mean_old;
+ double ssim_new;
+ double ssim_old;
+
+ // Not sure there's a great way to handle the edge pixels
+ // in ssim when using a window. Seems biased against edge pixels
+ // however you handle this. This uses only samples that are
+ // fully in the frame.
+ if (j + 8 <= width && i + 8 <= height) {+ ssimv_parms(img1 + j, img1_pitch, img2 + j, img2_pitch, &sv);
+ }
+
+ ssim = ssimv_similarity(&sv, 64);
+ ssim2 = ssimv_similarity2(&sv, 64);
+
+ sv.ssim = ssim2;
+
+ // dssim is calculated to use as an actual error metric and
+ // is scaled up to the same range as sum square error.
+ // Since we are subsampling every 16th point maybe this should be
+ // *16 ?
+ dssim = 255 * 255 * (1 - ssim2) / 2;
+
+ // Here I introduce a new error metric: consistency-weighted
+ // SSIM-inconsistency. This metric isolates frames where the
+ // SSIM 'suddenly' changes, e.g. if one frame in every 8 is much
+ // sharper or blurrier than the others. Higher values indicate a
+ // temporally inconsistent SSIM. There are two ideas at work:
+ //
+ // 1) 'SSIM-inconsistency': the total inconsistency value
+ // reflects how much SSIM values are changing between this
+ // source / reference frame pair and the previous pair.
+ //
+ // 2) 'consistency-weighted': weights de-emphasize areas in the
+ // frame where the scene content has changed. Changes in scene
+ // content are detected via changes in local variance and local
+ // mean.
+ //
+ // Thus the overall measure reflects how inconsistent the SSIM
+ // values are, over consistent regions of the frame.
+ //
+ // The metric has three terms:
+ //
+ // term 1 -> uses change in scene Variance to weight error score
+ // 2 * var(Fi)*var(Fi-1) / (var(Fi)^2+var(Fi-1)^2)
+ // larger changes from one frame to the next mean we care
+ // less about consistency.
+ //
+ // term 2 -> uses change in local scene luminance to weight error
+ // 2 * avg(Fi)*avg(Fi-1) / (avg(Fi)^2+avg(Fi-1)^2)
+ // larger changes from one frame to the next mean we care
+ // less about consistency.
+ //
+ // term3 -> measures inconsistency in ssim scores between frames
+ // 1 - ( 2 * ssim(Fi)*ssim(Fi-1)/(ssim(Fi)^2+sssim(Fi-1)^2).
+ //
+ // This term compares the ssim score for the same location in 2
+ // subsequent frames.
+ var_new = sv.sum_sq_s - sv.sum_s * sv.sum_s / 64;
+ var_old = sv2[c].sum_sq_s - sv2[c].sum_s * sv2[c].sum_s / 64;
+ mean_new = sv.sum_s;
+ mean_old = sv2[c].sum_s;
+ ssim_new = sv.ssim;
+ ssim_old = sv2[c].ssim;
+
+ if (do_inconsistency) {+ // We do the metric once for every 4x4 block in the image. Since
+ // we are scaling the error to SSE for use in a psnr calculation
+ // 1.0 = 4x4x255x255 the worst error we can possibly have.
+ static const double kScaling = 4. * 4 * 255 * 255;
+
+ // The constants have to be non 0 to avoid potential divide by 0
+ // issues other than that they affect kind of a weighting between
+ // the terms. No testing of what the right terms should be has been
+ // done.
+ static const double c1 = 1, c2 = 1, c3 = 1;
+
+ // This measures how much consistent variance is in two consecutive
+ // source frames. 1.0 means they have exactly the same variance.
+ const double variance_term = (2.0 * var_old * var_new + c1) /
+ (1.0 * var_old * var_old + 1.0 * var_new * var_new + c1);
+
+ // This measures how consistent the local mean are between two
+ // consecutive frames. 1.0 means they have exactly the same mean.
+ const double mean_term = (2.0 * mean_old * mean_new + c2) /
+ (1.0 * mean_old * mean_old + 1.0 * mean_new * mean_new + c2);
+
+ // This measures how consistent the ssims of two
+ // consecutive frames is. 1.0 means they are exactly the same.
+ double ssim_term = pow((2.0 * ssim_old * ssim_new + c3) /
+ (ssim_old * ssim_old + ssim_new * ssim_new + c3),
+ 5);
+
+ double this_inconsistency;
+
+ // Floating point math sometimes makes this > 1 by a tiny bit.
+ // We want the metric to scale between 0 and 1.0 so we can convert
+ // it to an snr scaled value.
+ if (ssim_term > 1)
+ ssim_term = 1;
+
+ // This converts the consistency metric to an inconsistency metric
+ // ( so we can scale it like psnr to something like sum square error.
+ // The reason for the variance and mean terms is the assumption that
+ // if there are big changes in the source we shouldn't penalize
+ // inconsistency in ssim scores a bit less as it will be less visible
+ // to the user.
+ this_inconsistency = (1 - ssim_term) * variance_term * mean_term;
+
+ this_inconsistency *= kScaling;
+ inconsistency_total += this_inconsistency;
+ }
+ sv2[c] = sv;
+ ssim_total += ssim;
+ ssim2_total += ssim2;
+ dssim_total += dssim;
+
+ old_ssim_total += ssim_old;
+ }
+ old_ssim_total += 0;
+ }
+
+ norm = 1. / (width / 4) / (height / 4);
+ ssim_total *= norm;
+ ssim2_total *= norm;
+ m->ssim2 = ssim2_total;
+ m->ssim = ssim_total;
+ if (old_ssim_total == 0)
+ inconsistency_total = 0;
+
+ m->ssimc = inconsistency_total;
+
+ m->dssim = dssim_total;
+ return inconsistency_total;
+}
+
#if CONFIG_VP9_HIGHBITDEPTH
double vp9_highbd_calc_ssim(YV12_BUFFER_CONFIG *source,
--- a/vp9/encoder/vp9_ssim.h
+++ b/vp9/encoder/vp9_ssim.h
@@ -17,6 +17,52 @@
#include "vpx_scale/yv12config.h"
+// metrics used for calculating ssim, ssim2, dssim, and ssimc
+typedef struct {+ // source sum ( over 8x8 region )
+ uint64_t sum_s;
+
+ // reference sum (over 8x8 region )
+ uint64_t sum_r;
+
+ // source sum squared ( over 8x8 region )
+ uint64_t sum_sq_s;
+
+ // reference sum squared (over 8x8 region )
+ uint64_t sum_sq_r;
+
+ // sum of source times reference (over 8x8 region)
+ uint64_t sum_sxr;
+
+ // calculated ssim score between source and reference
+ double ssim;
+} Ssimv;
+
+// metrics collected on a frame basis
+typedef struct {+ // ssim consistency error metric ( see code for explanation )
+ double ssimc;
+
+ // standard ssim
+ double ssim;
+
+ // revised ssim ( see code for explanation)
+ double ssim2;
+
+ // ssim restated as an error metric like sse
+ double dssim;
+
+ // dssim converted to decibels
+ double dssimd;
+
+ // ssimc converted to decibels
+ double ssimcd;
+} Metrics;
+
+double vp9_get_ssim_metrics(uint8_t *img1, int img1_pitch, uint8_t *img2,
+ int img2_pitch, int width, int height, Ssimv *sv2,
+ Metrics *m, int do_inconsistency);
+
double vp9_calc_ssim(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
double *weight);