1.Use libyuv instead of ffmpeg to do nv12<->yuv420p convertion;2.Use local package to build libyuv(branch stable 2021.4.28 commit eb6e7bb63738e29efd82ea3cf2a115238a89fa51)

thirdparty/libyuv/util/ssim.h

@@ -0,0 +1,38 @@
+/*
+ *  Copyright 2013 The LibYuv 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.
+ */
+
+// Get SSIM for video sequence. Assuming RAW 4:2:0 Y:Cb:Cr format
+
+#ifndef UTIL_SSIM_H_
+#define UTIL_SSIM_H_
+
+#include <math.h>  // For log10()
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if !defined(INT_TYPES_DEFINED) && !defined(UINT8_TYPE_DEFINED)
+typedef unsigned char uint8_t;
+#define UINT8_TYPE_DEFINED
+#endif
+
+double CalcSSIM(const uint8_t* org,
+                const uint8_t* rec,
+                const int image_width,
+                const int image_height);
+
+double CalcLSSIM(double ssim);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // UTIL_SSIM_H_