Re: Bug? Clicks while recording audio (In) from MIDI (out)
Re: Bug? Clicks while recording audio (In) from MIDI (out)
- Subject: Re: Bug? Clicks while recording audio (In) from MIDI (out)
- From: Doug Wyatt <email@hidden>
- Date: Fri, 21 Feb 2003 12:00:14 -0800
It sure *sounds* a lot like what I hear when I connect a MIDI Out to an
Audio In ... +5V at 31250 bps.
It's very hard to imagine how MIDI bits could find their way into a
digital audio stream. I assume you're recording with built-in audio?
It's not hard to imagine there being an electrical issue (grounding? I
dunno, I do software) ...
You're right that it gets harder to imagine why, if it were hardware,
it's not happening on 9. But the drivers on the two platforms are very
different, and therefore it is possible that the hardware is being
configured differently.
An interesting avenue of investigation would be to see if the noise,
when analyzed in a sample editor, has a regular mathematical pattern.
If so, then the interference is happening in the digital (i.e.
software) domain. If the noise is jagged and irregular, then it's
definitely coming from the analog (i.e. hardware) domain.
Doug
On Thursday, Feb 20, 2003, at 10:12 US/Pacific, Josh Whitver wrote:
Just a quick note to say that this bug remains in 10.2.4. I'm sure
it's not
an electrical interference issue as the problem goes away if I do the
same
thing (record audio coming in from my synth, which is receiving MIDI
data
from the computer simultaneously) booted in Mac OS 9. I'd be
interested in
knowing if someone with a similar setup (USB Fastlane MIDI interface,
G4/400
Gigabit) experiences the same kinds of problems recording audio in
from MIDI
out. Thanks!
This may sound a bit convoluted, but what I'm trying to do is really
pretty
simple. I have a MIDI file of a Piano Concerto that I'm writing that
I'm
trying to convert to a decent-sounding MP3 to post on my website.
I play the MIDI file out to my synth, and running the audio out from
my synth
back into the computer, recording the audio input with "Audio In", a
freeware app.
This works, except for one thing. Every time there's a MIDI note
event, I
get a strange click in the audio that's coming in. It's not from the
synth,
because the speakers on the synth don't register it. If I plug
headphones
into the keyboard (killing the internal speakers) and just monitor
the sound
on my computer speakers, there's the click, even if I turn the volume
on the
synth all the way down. It's like there's a chorus of tiny
fingernails
clicking away the rhythms of every part. I've put a short sample of
this
at:
http://www.whitver.net/coreaudiobug.mp3
Part way through this sample, I turned the volume on the synth all
the way
down, yet the clicks remain. They've gotta be coming from CoreAudio.
Further proof of this comes from the fact that if I boot into Mac OS
9, the
clicks are gone. I'm on a Gigabit G4/400, synth is a Yamaha PSR-520
hooked
up via USB FastLane MIDI interface.
--
Josh Whitver
email@hidden / email@hidden
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