The invention relates to an apparatus for the reproduction or recording of data or information with a photodetector and digital error signal and evaluation signal processing. The object of the invention is to provide an apparatus for the reproduction or recording of data or information which requires little outlay despite digital evaluation signal processing and a considerable capability of adaptation to different scanning speeds. The invention is based on the principle of enabling digital evaluation signal generation with an analog-to-digital converter known from audio technology, even though the data rate of the data or high-frequency signal requires an analog-to-digital converter for the radio-frequency or for the video signal band. An analog-to-digital converter for the audio frequency band can be used to generate a digital evaluation signal by the analog-to-digital converter having fed to it not the high-frequency signal directly but rather at least one envelope of the high-frequency signal. An envelope detector is also proposed, which envelope detector is advantageously suitable both for the purpose of providing an upper envelope and for the purpose of providing a lower envelope. The invention can preferably be used in apparatuses for the reproduction or recording of data or information with a photodetector and digital error signal and evaluation signal processing by means of which data or information are read from the data tracks of a recording medium or of different recording media or are recorded in tracks.