The "VMC Protocol" is a system developed to facilitate communication between the motion capture software known as "Virtual Motion Capture" and Unity, for the purpose of animating VRM avatars. As a result, VMC Protocol has been adopted not only in Unity but also in a wide array of avatar systems and software. Compatible software is listed on the official website of VMC Protocol.
The Microsoft Store version of the iFacialMocap app also supports the sending and receiving of VMC Protocol. Although VMC Protocol is originally designed to animate the entire body, iFacialMocap is specialized in animating only facial expressions and movements around the face.
Typically, VMC Protocol would also transmit information related to bone positions. However, the desktop version of iFacialMocap sends this bone position information as a constant zero. As a result, some software may experience irregular bone movements when receiving VMC Protocol from the iFacialMocap desktop app.
To transmit VMC Protocol from iFacialMocap and animate VRM avatars in Unity, it is necessary to use a Unity Package called EVMC4U. To ensure proper bone movement within EVMC4U, please uncheck the option labeled "Bone Position Synchronize."