Custom Blender Animation Export

I was success on export mesh data including vertices, normals and triangle indices.
However, I’m trying to export the animation data.
Here is the result for the skeleton exported:
You can click the url and wait for about 10 seconds then the animating skeletons (cubed) will appear.

This is the export code for the poses:

obj = context.object

pose = obj.pose
bones = {}

def traverseBone(bone):
            bones[] = bones.get( or []
                [a for row in bone.matrix.transposed() for a in row])
            for child in bone.children:

for frame in range(scene.frame_start, scene.frame_end + 1):

Assume this is only 1 root bone of the armature.

The problem is, the original vertices value is in range [0, 1] while to bone matrix transform the vertices to a larger range [0, 7] or more. thus the final animating result is like this:

You can see the man mesh is scaled according to the bones.

This is the formula for skinning:

outV = sum(weights[i] / totalWeights * boneMatrix[i] * v)

I want to know what other information I can extract from blender to make the skin correctly?