1. A signal processing apparatus comprising: first feature detection means for detecting a plurality of first feature data each representing a different feature from video and audio signals of a content; setting means for setting a weight for each of said plurality of first feature data detected by said first feature detection means, said weight corresponding to the feature for detecting data on the basis of said first feature data, said weight being varied either from one content to another or from one content genre to another; and second feature detection means for detecting a plurality of second feature data each representing a different feature on the basis of said plurality of first feature data for which the weights have been set by said setting means.