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/xmake.lua

@@ -0,0 +1,28 @@
+package("libyuv")
+
+    set_homepage("https://chromium.googlesource.com/libyuv/libyuv/")
+    set_description("libyuv is an open source project that includes YUV scaling and conversion functionality.")
+    set_license("BSD-3-Clause")
+    -- add_versions("20210528", "eb6e7bb63738e29efd82ea3cf2a115238a89fa51")
+
+    -- set_urls("https://chromium.googlesource.com/libyuv/libyuv.git")
+    -- add_versions("2023.10.27", "31e1d6f896615342d5d5b6bde8f7b50b3fd698dc")
+
+    set_sourcedir(os.scriptdir())
+    add_deps("cmake")
+
+    on_install("windows", "linux", "macosx", "android", "cross", "bsd", "mingw", function (package)
+        local configs = {"-DTEST=OFF"}
+        table.insert(configs, "-DCMAKE_BUILD_TYPE=" .. (package:debug() and "Debug" or "Release"))
+        
+        io.replace("CMakeLists.txt", "INSTALL ( PROGRAMS ${CMAKE_BINARY_DIR}/yuvconvert			DESTINATION bin )", "", {plain = true})
+        import("package.tools.cmake").install(package, configs)
+        
+        if package:is_plat("macosx", "linux", "android") then
+            if package:config("shared") then 
+                os.tryrm(package:installdir("lib", "*.a"))
+            else 
+                os.tryrm(package:installdir("lib", "*.so"))
+            end
+        end
+    end)