PCM, DTS, and AC3 tracks on Laserdiscs are all digital signals, modulated into an analog one (or something like that). Most LD players require an external demodulator to produce a standard digital signal which can then be fed to a decoder - or the SPDIF-in of a computer.

There are pitfalls though - I've never been able to get low enough access to the audio hardware to record a perfect digital rip on Windows 7, for example, and even on XP you may have a soundcard which ruins the data before you can get to it. Then there are random dropouts which might mean it takes 2 or 3 tries to get a complete rip.

DE