A method is disclosed for performing Beta prediction for high-speed writing on unknown recordable optical discs. Test recordings are performed in the inner (20) and outer test (40) zones of an unknown recordable optical disc, yielding results expressed as measured beta target values. At least one beta target value is computed in a data zone (30) of the unknown recordable optical disc. Beta (power) is predicted as a function of speed for continuous angular velocity (CAV) speed profiles, or equivalently, as a function of disc radius for CAV writing, for high speed writing on said unknown optical disc by constructing a piecewise linear interpolation of beta versus speed or disc radius using the measured target values and the at least one calculated beta target value.