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: Josh Whitver <email@hidden>
- Date: Sat, 22 Feb 2003 23:12:11 -0600
My theory is that it's purely a software issue, ie, there's something in the
audio-in code of CoreAudio that winces whenever the CoreMIDI aspect of
CoreAudio is busy. So, whenever there's a MIDI event, CoreAudio's Audio In
just hiccups.
The only reason the interference is so regular is that there's a steady
stream of eighth-note triplets in the string section, and the piece is at a
quarter note=130, which is really close to 2 beats/sec, which is a pretty
natural-sounding tempo.
>
It sure *sounds* a lot like what I hear when I connect a MIDI Out to an
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Audio In ... +5V at 31250 bps.
>
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It's very hard to imagine how MIDI bits could find their way into a
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digital audio stream. I assume you're recording with built-in audio?
Yes, but it's the last model that had analog audio-in. Also, like I
mentioned above, I'm operating under the assumption that it's a purely
software-related issue (ie, the audio is actually coming in crystal-clear,
but CoreAudio just can't handle listening to the audio-input port while it's
busy sending MIDI data out).
>
>
It's not hard to imagine there being an electrical issue (grounding? I
>
dunno, I do software) ...
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You're right that it gets harder to imagine why, if it were hardware,
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it's not happening on 9. But the drivers on the two platforms are very
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different, and therefore it is possible that the hardware is being
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configured differently.
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An interesting avenue of investigation would be to see if the noise,
>
when analyzed in a sample editor, has a regular mathematical pattern.
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If so, then the interference is happening in the digital (i.e.
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software) domain. If the noise is jagged and irregular, then it's
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definitely coming from the analog (i.e. hardware) domain.
>
>
Doug
--
Josh Whitver
email@hidden / email@hidden
"Out of my mind. Back in five minutes."
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