Optical disc reproducing apparatus, signal processing apparatus and method of the same

A signal processing apparatus for processing a reproduced signal reproduced from an optical disc, comprising:

• a band restricting means for applying a band restriction that removes the low frequency component contained in said reproduced signal in a period for which said reproduced signal has a high frequency and applying no band restriction with respect to said reproduced signal in periods other than the period for which said reproduced signal has said high frequency;
• a detecting means for detecting a level fluctuation of said reproduced signal;
• and
• a controlling means for controlling said band restricting means in response to said level fluctuation detected by said detecting means.

A signal processing method for processing a reproduced signal reproduced from an optical disc, comprising the steps of:

• applying band restriction processing that removes a low frequency component contained in said reproduced signal in a period for which said reproduced signal has a high frequency and does not remove said low frequency component contained in said reproduced signal in a period for which said reproduced signal does not have said high frequency;
• controlling the gain of the reproduced signal to be apply said band restrinction processing in response to the level fluctuation of said reproduced signal reproduced from said optical disc;
• and
• coding said band-restricted reproduced signal.