An optical disc playback apparatus that performs appropriate waveform equalization
according to a difference in characteristics of reproduced signals between land
parts and groove parts in an optical disc to which high-density recording is performed
using a land/groove recording method. The optical disc playback apparatus includes
a reproduction device, an A/D conversion circuit for sampling a reproduced signal
to be converted into a multi-bit digital signal, a filter for subjecting the multi-bit
digital signal to digital equalization, a filter coefficient learning device for
adaptively controlling filter coefficients for the filter corresponding to the
land part and the groove part to minimize an equalization error, and a switch signal
generation device for generating a signal for switching between land and groove,
thereby changing the filter coefficient adaptively to the land or the groove.