Gareth Halfacree wrote:
Rob wrote:
I'd never thought of that 33s at 45 ruse to save time - does it
actually degrade quality?

Indeed it does. Let's say you capture your audio at 44.1KHz (CD
quality, in other words). That's 44,100 samples per second (apologies
if I'm teaching my grandmother to suck eggs with this bit).

If you run your 33s at 33 RPM, then every second of captured audio
contains a full 44,100 samples.

If you run your 33s at 45 RPM, then every second of captured audio
contains 32,340 samples. Because these are played back at the rate of
44,100 samples per second it sounds too fast, so you have a choice of
either dropping the sample rate to 32,000 (32KHz, often referred to as
'Radio Quality' in older Windows applications) and discarding some of
your samples or slowing the whole thing down and keeping it at 44,100
samples per second. Which means interpolation (or, to put it another
way, inventing extra samples). Which means reduced quality.


Interesting, thanks for that. I suppose an analogy might be photo
compression?! I've often seen the 'time stretching' feature in audio
apps, but have never been sure how it works.

That's as I see it, anyway. But then again, what do I know; I'm a
computer tech, not an audiophile or broadcaster. I do own a turntable,
but it's manufactured by Aiwa and thus is likely to earn me the scorn of
everyone present.


Ah, not I, hats off to you with your feet firmly planted on the ground :-)

Rob