Disc playback apparatus

Apparatus for use in reproducing digital information including main digital data and subdigital data, from an optical digital disc, in which the main digital data and the subdigital data are recorded in a common track on the disc, comprising:

• means connected to receive digital information reproduced from said disc for generating a write clock signal synchronized with the reproduction rate of the digital information;
• an oscillator for generating a readout clock signal having a fixed period;
• means for separating the main digital data and the subdigital data from the reproduced information signal;
• a random access memory connected to receive said main digital data reproduced from said disc and being connected for writing therein said main digital data in response to said write clock signal, said random access memory being connected for reading out main digital data written therein in response to said readout clock signal;
• a buffer memory connected to write therein said subdigital data reproduced from said disc in response to said write clock signal and arranged for reading out said subdigital data written therein in response to said readout clock signal;
• and
• control means for searching a playback location of the main digital data in response to said subdigital data read out from said buffer memory.