Ramblings on ripping

Discuss macOS Audio in general and anything that doesn't fit elsewhere.
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Joined: Mon Oct 15, 2007 7:36 am

Ramblings on ripping

Post by chux » Sun Nov 11, 2007 10:39 pm

Here are some of my ramblngs in ripping, any thoughts? I'd love to learn more about this.

My understanding of OSX is purely at the level of the GUI, but I have been playing around with Max and iTunes, and looking the resulting file sizes.

Initially I looked at the difference between the size of the AIFF file on the CD and the ripped AIFF, and there always seemed to be a difference between the two. Usually a matter of 100 bytes or fewer. At first I assumed that this is because the ripping drive won't always start and finish the rips in exactly the right place? Perhaps it because there are subtle differences in the way that AIFFs are stored on CD versus HD? (do we need 8-14 on a HD)?

What I also noticed is that not all of my drives would give consistent file sizes for the same tracks ripped into ALAC. I attributed this to the fact that although two AIFFs of the same track could be the same size and still be non-identical, it was highly unlikely that two ALACs of the same track would be the same size if they were non-identical (ALACs ripped with iTunes and ripped with Max are non-identical). So I ditched those, and that left me with just 1 brand new DVDR/W drive. (edit: or so it seemed, the variance in file size seems to be attributable to the Firewire bridge [911+] or other aspects of the FW interface). I have tried ripping the same track on a good CD to ALAC multiple times (6) and on each occassion I get the same file size, so I am reasonably confident that my DVDR/W is producing consistent results, i.e., I am getting (almost all of) the data that I am supposed to get, and certainly as much as I need if the CD is undamaged.

I can do two consectutive rips of the same CD and compare the folder sizes (in bytes), if they're the same then it seems safe to assume that both rips are identical. If there is a difference, then the individual tracks can be compared and when two tracks have different sizes I know that something has gone wrong with the ripping of that track. Usually there is some physical damage to the disc. BTW, is there a way of automating this process?

Of course, problems arise when there is damage to the disc. The first step would be to try cleaning and/or polishing the disc so as to be able to get consistent results. If this works then all-good, but if it doesn't one has to either just listen to a number of rips and decide which is the best sounding or start to implement a technological solution a la EAC (et.al.)

I propose that the 'listen to it and keep the best' is as good as any solution. As long as you can get a copy without any audible glitches (could native-CD error correction be implemented in software?). Because there is never a guarantee that we're going to get an exact copy of the data that was on the master, simply because we don't have access to that disc, and even if we did, what method would we use to determine what was on that disc? With nothing to compare it to, we'd have to play it a number of times and then keep either the 'best' or the 'most consistent' results...

Also, is there an explantion of exactly what paranoia and comparison rippers are doing anywhere?



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