At 11:01 AM 7/19/99 +0100, Barnesey wrote:
>> Kade Hansson wrote an informative piece about audio formats, but:
>>
>>
>> A 22kHz sine wave is on the fringe of human heaing. However, a CD will
>> convert this to a square wave,
>>
> I think the input from the master is filtered to remove all
>frequencies above some frequency slightly BELOW 22 kHz. And the CD would not
>reproduce a 22 kHz sine wave as a square wave, because of the output
>filtering, which would remove the harmonics, leaving a fairly smooth sine
>wave.
You are probably right. But I am a digital man, and a wave form is a series
of flat steps lasting for 1/frequency. For me, if a signal is +32767 for
1/44.1 ms and then -32767 for 1/44.1 ms in the next sample, we have a
square wave. I am glad CD players smooth this into a sine/sawtooth wave
(assuming infinitesimal samples), but then we have the same problem for
producing a true square wave as we might've for a true sine or sawtooth
wave. The result is unchanged though- this is clearly the limit of the format.
>> (which is hardly relevant to your average listener, who has more problems
>> in their amp than from digital artifacts)
>>
> No question. I can't tell a 15 kHz sine wave from a 15 kHz square
>wave.
Neither can I. But they are different, which is what the number crunching
audiophiles will throw at you.
>> A steep sine wave simply cannot be accurately represented at a 44.1kHz
>> sample rate.
>>
> Not sure what this means.
I mean that you can't draw a *particular* smooth line (the intended
waveform) when you only have two points on that line (samples with their
centre points 1/44.1 ms apart). Any line you draw is an approximation to
what might have been intended. In the acoustic domain, we can theorize that
a sine curve would be a good bet, but there even a few ways we can draw
that through two points.
But I seem to be arguing a case even I don't believe in, so I'll shut up. :-)
The point is that this is how the audiophiles justify a greater sample rate
than 44.1kHz- "more points = smoother lines = nicer sound". I too think
this is crap, but at "smoother lines = nicer sound", not "more points =
smoother lines". I may be convinced otherwise given some science on human
perception of ultrasonics and otherwise inaudible harmonics, but for now, I
think it's crap. :-)
Anyway, I'm glad to have fostered such a discussion. It's interesting to
hear what prosumer digital-heads think of this debate. I think I may have
to agree that DVD-A is doomed if your collective views are as popular as I
suspect.
Cheers,
Kade- who's quite happy with 128kbps MPEG layer 3, really. :-)
--
Archer
http://www.geocities.com/SoHo/6413/
End.
-----------------------------------------------------------------
To stop getting this list send a message containing just the word
"unsubscribe" to [EMAIL PROTECTED]
