Combining Recordings From Two Devices

  • Thread starter Thread starter TromboneAl
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TromboneAl

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I'm experimenting with recording my jazz trio. I'm trying an interesting (weird?) setup:

I record with a Zoom H2.
I also record by plugging my electric keyboard directly into my laptop, and recording with Audacity. So, the Zoom records the three of us, and the laptop records only the piano. I then combine the two recordings in audacity, lining up the two audio streams. This gives me the ability to adjust the relative volume of the piano versus the other instruments.

Here's a weird problem I don't understand.

This works OK for a tune recorded at the beginning of the rehearsal (I leave both devices on all the time). Here's an example:

View attachment BlueBossaExcerptCombined.mp3

However, for a tune recorded towards the end of the rehearsal, it does not work:


View attachment TynerCombined.mp3

Apparently, the "time base" is off somehow, so that even if I line up the tracks, they very soon get out of sync.

Can anyone shed any light on this? Is there anything I could do to improve this?


Using XP and Audacity 2.0.0.
 
If the clocks on the converters are accurate, or at least have matching inaccuracy, then it should be possible to line the audio up well enough to keep it in sync for at least a song or two. If they are going out of sync that quickly then at least one of the AD converters has an inaccurate clock. Most likely the laptop's cheap audio input is to blame.

There are tools in most audio software for stretching the audio. You would want to use the mode that does not attempt to keep pitch unaltered (correcting playback speed should also correct the slight pitch error). But maybe the best solution would be to trade up to the H4n to get 4-track recording in one device.
 
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