Question _CameraMotionVectorsTexture meaning/definition

Hey, does anyone know how exactly _CameraMotionVectorsTexture is defined?
If I do

Code (CSharp):

1. tex2D(_CameraMotionVectorsTexture,In.uv);

which channel decodes the motion in x-direction? Which for the y-direction?
In which range are the numbers decoded?

From my experiments I determined the following:
- g-channel decode movement in x-direction
- r-channel decodes movement in y-direction
- they numbers probably range from -1 to 1 for each direction. However, they are very small! Without scaling them by a factor of at least 1000 they are bascially useless.

Are those oberservation correct?

 

AFAIK the built in rendering path stores the values as:
red channel = x direction in screen UV space.
green channel = y direction in screen UV space.
This means a value of 1.0 (or -1.0) in either means the object moved the width or height of the screen between the previous frame and current frame.

The SRPs appear to use the same rg = xy, but stored so you have to do rg * 2.0 - 1.0 to get the UV range, and clamped to be between -1.0 and 1.0 after decoding, where as the built in pipeline doesn't clamp the values.

 

Thank you for your answer! This clears it up for me!