I'm trying to adjust the orientation of my camera using two quaternions, based on their difference. So for a minimal rotation, I want the animation to take little time, and a bigger rotation to take longer. I guess I want to rotate the camera at a certain velocity.
Is there any way to combine the yaw, roll and pitch to get a single radian, so I can use that to calculate what percentage of the quaternion I want to apply each frame?
If you vant to differenciate the two quaternion just use the ToAngleAxis of the delta quaternion. It returns the angle (you need this) and the axix of the rotation between the two quaternions.
You can use quaternions and the calculated speed to calculate spherical interpolation (slerp for short), which allows you to calculate intermediate states for your camera orientation.