fix: checks for DLLs before calling NvEncoder APIs

[DannisMa]

Some CUDA platforms do not support NvEncoder, so using the relevant API without confirmation will cause a crash. https://github.com/Unity-Technologies/com.unity.webrtc/issues/806 I referred to Nvidia's GitHub project, we can see that it checks for DLLs before calling NvEncoder APIs. https://github.com/NVIDIA/video-sdk-samples/blob/aa3544dcea2fe63122e4feb83bf805ea40e58dbe/Samples/NvCodec/NvEncoder/NvEncoder.cpp#L58

[unity-cla-assistant]

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[karasusan]

DLL check is already here.

https://github.com/Unity-Technologies/com.unity.webrtc/blob/74627ff217019b11936c2eba016f876276b52d33/Plugin~/WebRTCPlugin/GraphicsDevice/Cuda/CudaContext.cpp#L34-L59

Can you tell me when you have a crash?

[DannisMa]

Maybe you should also check for the presence of 'nvEncodeAPI64.dll' because, in my situation, the project abruptly close after importing the WebRTC package without generating any crash logs in "C:\User\AppData\Local\Temp\Unity\Editor\Crashes".

Unity version: 2022.3.9f1 Package version: com.unity.webrtc@3.0.0-pre.6

[karasusan]

@DannisMa If you put the code which you suggested to CudaContext.cpp, is the crash stopped?

[DannisMa]

@DannisMa If you put the code which you suggested to CudaContext.cpp, is the crash stopped?

Yes， the crash is stopped and the project works well.

[karasusan]

@DannisMa I would like to aggregate the checking process in one part in code. Can you move the checking process to CudaContext.cpp ?

     static bool FindModule() 
     { 
         if (s_hModule) 
             return true; 

 #if UNITY_WIN 
         // dll delay load 
         HMODULE module = LoadLibrary(TEXT("nvcuda.dll")); 
         if (!module) 
         { 
             RTC_LOG(LS_INFO) << "nvcuda.dll is not found."; 
             return false; 
         } 
         s_hModule = module; 

>>> 
>>> // add checking process here
>>> 

 #elif UNITY_LINUX 
...

[DannisMa]

@karasusan Okay, I've already moved the checking process to CudaContext.cpp.