Subject: Re: MP3 rippng too slow
From: Gordon Neault (gordo-x@shaw.ca)
Date: Mon Mar 11 2002 - 21:03:45 MST
"... Send it to a windows user and see what they think of it. Quicktime
Pro (and I
have the add on codecs and such) is much the same.
The on the MB sound chip that Apple supplies is hardly of the sound quality
that a Creative sound card (such as the audigy) supplies - I'm not even
sure
you can truly judge with out it.
What I listen to is my SB card piped through a Pioneer connected to 4 Bose
Speakers (501's) so I can deffinately tell the diference. ..."
No comment.
As for creating audio, let's see...
From PC CD drive, 44.1/16bit sound is coverted to analog by the CD drives
onboard D/A converter. (Wonder how much that chip costs?). It then is
digitized by the SoundBlaster's A/D converter to 48K/16bit (SoundBlasters
cannot process 44.1 CD's natively, they have a 48K DSP chip. it's a
cost-saving measure. Resampling a 44.1 signal at 48K cannot fail to
introduce jitter and waveform abberations; CD's should always be upsampled
to 88.2 or some other whole multiple/or downsampled at an even fraction to
maintain waveform integrity) where it is then resampled/reconverted and
compressed by one of the mp3 CODECS (hopefully the PC user is using 48/32/
24/16/8 Khz or more errors will be introduced); whereupon it is resampled
once again to a multiple/fraction of 44.1 when burned to CD (otherwise it
won't play on a CD player).
From the Mac drive, 44.1/16bit sound is sent directly as a bit-for-bit
digital datastream to your burning app, whereupon it is resampled (but not
reconverted) and compressed by one of the mp3 codecs (hopefully the Mac
user is using 44.1/22.05/11.025 Khz; he will be if he selected "Auto" in
iTunes preferences) and then sent without resampling/reconversion as a
digital datastream to the burner. Hmmm, not a single DSP chip involved;
wonder how Apple's "on the MB sound chip" could even play a role, since it
never sees a signal.
The SoundBlaster cards are not bad at reproducing audio, they do have a
very difficult job maintaining quality when actually dealing with a
digital signal, though, considering all the work they must do. The Mac
never sends any signal to a DSP chip during the entire copy/encode/burn
process; the only time a DSP chip is involved would be when playing back
through the audio out minijack through conventional speakers. If the HK
speakers are "Digital Audio" USB types, D/A conversion and analog sound
playback would be via Harmon Kardon's DSP chip, not the Mac's. In any case,
it's been a very, very long time since a Mac actually used the el-cheapo
D/A converter included with your average $40 CD-ROM drive, though.
It's also my understanding that the Audigy's DSP chips are much better
than the typical SoundBlaster's, but I do believe they must still resample
to 96K (instead of the older SB Live!s 48K; but not the preferred 88.2,
which would be able to accurately reproduce the original RedBook CD
waveform).
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