Hi, The simple answer is FLAC.
A more complex answer is that audio CDs don't actually contain files or a regular filesystem at all. Some O/Ses allow you to view the CD as if it contained files, but they aren't files in the normal sense.
OGG, assuming this means OGG/Vorbis, is a lossy format. I don't know .cda. WAV is a lossless and uncompressed Microsoft format. FLAC is free format which is losslessly compressed. I would rip all CDs as FLAC then you have the original data. You can then compress this to OGG/Vorbis or MP3 later, which should be fairly easy and can be batch processed for all tracked ripped from all CDs.
If you're ripping lots of CDs then I've used a program called 'abcde' which might be useful. It can be configured to output FLAC and get the track names from the internet. It does some parallel processing too, compressing the original data to FLAC in the background.
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