I am trying to get my animations that i’ve created using perception neuron mocap suit into UE4, I clean the mocap in motionbuilder. I’ve tried every which way i can think of importing the clean mocap into ue4 and keep getting terrible results (see attached). I firstly tried to use the motionbuilder to ue4 live link and everything looks good until you actually record the animation and open the created sequence then thats where the bad deformities start. I secondly tried just importing the saved file into ue4 and get the same results. I also tried retargeting with multiple meshes and still getting the same results whether the meshes have the same bone or not. I’ve tried using the same custom mesh file in both and get the same result. IDK if this is a MB problem or a UE4 problem so im posting on both forums hopefully yall can help me out this bug or whatever has put my production behind schedule thanks in advance for any input. - YouTube
Well from what I see your problem is neither MB or UE4 related but rather a set up problem as to the rules that will help make the result a lot more predictable. In this case for the transfer to work the animation must match the rig in question when applying absolute animation.Since the characters are of two different sizes the behaviour would be expected as a transfer of animation data from a much larger character to a smaller one.
I’m sure there is a way to fix this in UE4 as I’ve seen it but as someone who does use Motionbuilder the process for me is rather redundant as all things re-targeting related can be done much easier in Motionbuilder with out having to go the long way around.
To get your head around re-targeting just Google “retargeting animation in motionbuilder” as well for the purpose of authoring animation learn MB and not UE4 
thanks for the reply but as i said in the original post, I’ve attempted the way you’re speaking of opening the same fbx mannequin file in both programs then live linking and tried doing it the with the fbx girl mesh also the arms are always messed up. I also have tried just editing & retargeting in MB exporting the file then importing it into UE4 and i get the same results. I’m not new to retargeting this pipeline i’m using actually worked a few months ago idk whats going on now so it gotta be one of the programs it all looks good until i attempt to put the finished work into UE4 and get those terrible results.
It looks like your arms bone chain and weight paint is waaaaay off.
Almost as if you are using blender’s BB bones on the arms.
Since the mannequin animation apparently works (it’s bad, you should make it way more steady, but it works) - the issue cannot be your animation.
doubleck that you setup your bone as Advanced for both of the rigs to re-target.
test by retargeting other existing mannequin animations (jump start / jump land), anything that moves the arm will either present similar issues, or work.
If any of the mannequin default anims just work, then you may have imported the animation we see on the mannequin with it’s own skeleton instead of using the mannequins skeleton.
Hard to say by just looking at the video.
Like Frankie suggested, you would be better off applying the animations to the skeleton you are actually using directly in a 3D program.
maybe you would even be better off “filming?” Directly on the skeleton you need to animate.
Well the problem is the difference in size causes the bones to attempt to reposition as referenced by the Epic rig. In Motionbuilder if you merge your character into MB and characterized they then “both” share the same hierarchy based on Motionbuilders naming convention and you then only need to select the Epic rig as your game character input and then use Live Link. On the other hand if you save out the animation you can set up the re-targeting to account for scale transforms but sort of defeats the purpose of adding MB to the pipeline.
Here is a good example of retargeting in Motionbuilder using an Epic rig and a Mech. A bit advance but a good over the top example of what you want to do in MB. In UE4 to use Live Link you would import the Mech into UE4, as it matches the MB version and point the connection to it. You now retargeting the raw animation data from the Epic rig to the Mech through the Live Link to the Mech in Unreal 4. 
So I did a bit of research and since you have Motionbuiler and Perception neuron mocap device then the easy way is to content the suit to MoBu. Motionbuilder my it’s self is for practical reason is a head application for most if not all motion capture devices and as luck would have it Perception has a device available to MB for just that purpose.
Once connected you can characterize your in game model and set it’s input to target the Perception input and tada MB will automatically adjust the spacial difference for you.
(FrankieV) I know i’ve been using that plugin that’s how i’m getting the unedited motions into MB, I open up the UE4 version of the mesh i want to retarget the mocap to in MB retarget it then delete thenueron skeleton and device. i connect UE4 Live link (Importing never worked) to record it and that’s where the problem lies after i’m done recording and UE4 creates the animation i get the results you see in the video. How would i make it more steady? There’s no options to cut the jittering out in PN
(MostHostLa) I create all my characters in CC3 so i don’t really do nothing to bones at all, whatever script they have firing off when i choose to export a mesh with ue4 settings does all that. But where do i setup the bones to advanced like you said? & i tried your suggestion and the arms are still messed up but the rest looks good.
Ok guys so everything is back working and all i did was delete and reinstall the plugins every mesh is retargeting just fine lol. I guess the plugins were out of date or something my pipeline back up and working thanks for you guys input i really appreciate yall taking the time to check and critical think with me.