CD-R quality (was Re: Shameless CDR vs CD questions)

[Stephen Swann]

On Mon, Feb 18, 2008 at 12:51:41PM +0000, Paul Mather wrote:
>
> The data CD gets less data per sector because they use some of the raw  
> sector data for extra data integrity checking: it's more important  
> that you detect that the balance in your bank spreadsheet file has  
> erroneously changed than some audio samples in a frame.  The former  
> would be potentially catastrophic, whereas the latter would probably  
> be perceptually unnoticeable.

... except of course that audio CD error is often a lot worse if
the physical disc is even slightly marred, and if I ever had a
chance to time travel and chat with the people who made that
decision about Audio CDs, I'd want to have a pair of iron tongs
and a blowtorch with me.

> (BTW, the main reason expensive CD players sound better than cheap  
> ones is due mostly to the better quality of the analogue components.)

I'd agree with that ever since advanced error correction
technology got cheap - what *used* to be the biggest difference
was how well they coped with imperfect CDs...

> It's not true that you can't make a bit-identical copy of an audio  
> CD.
 [...]
> So, to make bit-identical copies, you need: a) decent CDDA extraction  
> software aware of the issues (e.g., EAC; cdparanoia; etc.), and b) to  
> calibrate your CD drive.  There are lots of tutorials on how to do  
> this, via a variety of mechanisms, on the Web.  (E.g., do a search for  
> "EAC sample offset".)  Some extractors, like EAC and dBPowerAMP  
> support AccurateRip, which lets you calibrate your drive with respect  
> to a database of known pressed CDs and even compare your rips with  
> others.

I'd just like to note that I went to MIT and I found it difficult
to get my head around all the ins and out of digital audio
extraction - finally concluding that the effort-to-results sweet
spot was somewhere around 99.8% certainty.  So be warned, it's
not *quite* as simple to do this as Dr. Mather (an expert on the
subject) makes it sound...  No offense Paul - I know you give us
all more credit than we deserve.  ;-)

Steve