It's really hard to explain why upsampling works without resorting to graphs. Basically, audio theory says that 40,000khz is adequate to play back a 20khz sinewave. But if you think about it, a sampling rate of only 44,000 hz gives a VERY crude approximation of a sine wave. Sure, the peaks and the valleys are there, but the sine wave now looks more like a square wave than a sine wave.
With upsampling, you can interpolate that waveform to *approximate* a sine wave. Obviously, the best solution would be to do the original recording at a extremely high sampling rate.
John
P.S.
Here's my graph:
Analog 20khz sine wave : ** ** * * * * * * * * * * * * ** and here's what a 44khz DAC does to a 20khz signal:
**** **** **** **** **** **** **** **** ****
As you can see, there's little more than a passing resemblance to a sine wave at that sampling rate, the interval is too coarse.
-----Original Message----- From: owner-bass@lists.cc.utexas.edu [mailto:owner-bass@lists.cc.utexas.edu]On Behalf Of Hans Laros Sent: Thursday, February 21, 2002 12:55 AM To: bass@lists.cc.utexas.edu Cc: mad-user@lists.mars.org Subject: Re: Huuuuuuuge Improvement to My Stereo
mmm,
although it sounds silly that compressing and upsampling would better the soundquality, I remember a review of the 18-bits DCC player (sadly lost the war with minidisc) where a few panel meber actually thought that the dcc (blind test) sounded more analogue / less grainy / clearer than the original cd that was included in the blindtest aswell. Can't remember the cd-player in question, but they did use a very high quality one.
Regards,
Hans.
----- Original Message ----- From: "John van Ommen" jvanommen@verio.net To: bass@lists.cc.utexas.edu Cc: mad-user@lists.mars.org Sent: Thursday, February 21, 2002 9:40 AM Subject: Huuuuuuuge Improvement to My Stereo
If any of you do a lot of listening at your PC, I ran into something today that may be of interest.
I've been listening to MP3s on the command line using madplay.exe, cuz winamp sounded like ass, even with the MAD plugin. It turns out that a upgrade of wimamp had replaced my "wave out" output plugin in Winamp. As far as I can tell, the MAD input pluging was outputting a 24bit stream,
and
I think the wave out plugin was truncating it down to 16bit.
Nonetheless, I fixed the output plugin, and the difference is h-u-g-e. 24/96 soundcards playing MP3s upsampled to 24/48 really give CDs a run for their money. Especially at high volumes, the extra dynamics of 24bit are clear, and it seems like you can see 'deeper' into the recording as well.
John van Ommen