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I've recorded a melody line with my guitar in two separate takes and I'm trying to stitch them together. Around the stitching point, there's a noticeable "crack" in the audio. I don't hear the crack when I listen to the clips individually.

How can I eliminate the crack? Can I somehow use a crossfade as a way to smoothly transition from one clip into the other? I'm using GarageBand 10.1.3. I don't know if this has an impact at all, but I used the Flex feature to correct the timing on some notes.

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    Unless you are cutting at visibly 'sensible' points - zero crossings at noticeably quieter sections, then crossfade will be your saviour. Unfortunately I've never used Garage band, so idk how to do it in there.
    – Tetsujin
    Nov 20, 2016 at 19:12
  • cross fade between the 2 waveforms and you'll be fine :)
    – frcake
    Nov 20, 2016 at 21:15

2 Answers 2

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The "crack" is caused by a discontinuity in the audio waveform between the two regions. The way to solve this is to apply a "crossfade" between the two regions. This will smooth out the waveforms as they fade between regions and will ensure that the "crack" is not audible. When working with dis-similar regions, then you will want to use a "logarithmic" crossfade if at all possible. This ensures that the "power" of the audio across the fade is maintained at a constant level - and you don't hear any "dips" or "bumps" in the audio as the play head moves across the crossfade.

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  • Thanks for giving a theoretical solution and explaining some of the science behind it, but I don't know how I would easily go about doing it in GarageBand. It supports volume envelopes, so I could use two tracks and tweak the envelopes so that it emulates a crossfade.
    – Pieter
    Nov 24, 2016 at 21:54
  • Unfortunately that is often what has to be done in these situations. FCPX is the same.
    – Mark
    Nov 24, 2016 at 21:56
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Ideally, you cut the audio at a zero crossing point (or very close to it) as described by Tetsujin. if that's not possible due to the clumsiness of the tools, then you could use volume envelopes, but in most cases that will lead to noticeable disruptions in playback

I would consider putting the two clips in different tracks, and using volume automation to turn the first clip down to mute, and second clip up from mute, at the same time, so that you create a manual crossfade.

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