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Tech question about sampling rates and levels | David Bowie's "Reality" DualDisc


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#1 of 2 OFFLINE   Will_B

Will_B

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Posted March 09 2010 - 07:34 AM

I've been examining David Bowie's DualDisc of Reality from 2003, and I've discovered something odd that prompts a technical question.

Unlike, say, Fiona Apple's DualDisc, which featured 48kbps/16 bit stereo audio at normal levels (approaching 100%), David Bowie's Reality features 48kbps/16 bit audio that tops out, quite inexplicably, at 75%.

The album is pretty brick-walled so it is easy to see on the waveform that whoever mastered the DualDisc turned it down from 100% to 75%, across all the songs.

My question is this:

The improvement in audio quality offered by the 48 kbps / 16 bit DualDisc, versus the 44.1kbps/16 bit CD, is minor to begin with (even in an ideal situation where both levels were at 100%).

So -- my big question -- what happens to that slight improvement in quality when the audio levels of the DualDisc were reduced to 75%? Does that reduction in the levels essentially eliminate even the marginal improvement in the audio quality that the DualDisc provided? Or do levels not factor into quality?

In other words, is a "75% level of 48 kbps / 16 bit" worse than "100% level of 44.1 kbps / 16bit"?


By the way, the only reason I discovered this strange 75% level of Reality is that I am experimenting with using Apple Lossless instead of 320 kbps for my iTunes; I figured I may as well start with the discs that had great sound quality -- and that included my DualDiscs' DVD layers (whenever a DualDisc offered a higher-resolution stereo version of the album). As I said earlier, Fiona Apple's Extraordinary Machine DualDisc did not have any strange reduction in levels. I don't have others to compare.


 

"Scientists are saying the future is going to be far more futuristic than they originally predicted." -Krysta Now

#2 of 2 OFFLINE   Will_B

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Posted March 09 2010 - 06:24 PM

On another forum in which I asked this, it was suggested that 75% would make the "16 bit depth" really just 12 bits, which makes sense (75% of 16 bits is 12 bits).

So then the question is,

Is 48 kbps/12 bits better or worse than 44.1 kbps/16 bits?

"Scientists are saying the future is going to be far more futuristic than they originally predicted." -Krysta Now