Discussion Performance, Marshal.Copy and NativeArrayUnsafeUtility.ConvertExistingDataToNativeArray

Hi,

Our project shows remote webrtc video in unity Texture2D. The Video image data is captured from C++ native code.
Currently, we copy the native image data to c# byte[] using Marshal.Copy, I think we should have a better way to avoid marshalling costs. (Remark: After I copy the data, native c++ will delete the data buffer, I can't control it)

I hava two questions:
1. Is NativeArrayUnsafeUtility.ConvertExistingDataToNativeArray with Allocator.Persistent is better than Marshal.Copy to c# byte[]?

2. Will the garbage collector free the NativeArray aotumaically? Will it call NativeArray.dispose()? Because another main thread will read the NativeArray to Texture2D, I can't free it in the backgound thread.

Thanks!

 

You can allocate buffer at C# side and pass it into C++ so C++ size fills it.

Basically, C#:

Code (csharp):

1.  
2.     public static extern void processImage(
3.         [In, Out] Color32[] src, int srcWidth, int srcHeight
4.     );
5.  

C++:

Code (csharp):

1.  
2. void processImage2(RGBA *src, int srcWidth, int srcHeight){
3. .......
4. }
5.  

However, you do need to raincheck if copying is performed behind the scenes anyway.

In general interop between C# and C++ is not very pleasant, due to need to copy data often, plus you need plenty of glue code.