Video Conversion in .net core MVC.

Question

I have use this code for video convert but i have face a issue .

var ffmpeg = new NReco.VideoConverter.FFMpegConverter();
NReco.VideoConverter.License.SetLicenseKey(
"************"
);
ffmpeg.FFMpegExeName = "ffmpeg.exe"; // for Linux/MacOS: "ffmpeg"
ffmpeg.FFMpegToolPath = webHost.WebRootPath + "//lib//";
ffmpeg.ConvertMedia(pathToVideoFile,outputFile+".mp4", "mp4");

FFMpegException: (exit code: 1) --this error face .Please help me.