Сергей

public string Info()
        {
            Process process = Process.Start(new ProcessStartInfo
            {
                FileName = "ffmpeg",
                Arguments = $" -i {Input} -hide_banner",
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
                CreateNoWindow = true
            });

            while (!process.StandardError.EndOfStream)
            {
                info += process.StandardError.ReadLine()+ "\n";
            }
            info += "чтение завершено";
            return info;
        }