punch and roll adds a bit of waveform at split point

Hi! I’m a little bit new to Audacity, having used Twisted Wave for a while, and I enjoy lots of Audacity’s features and customizable commands. Anyway, with punch and roll, when I select a punch-in point and record, it adds a bit of unwanted waveform, strangely, from earlier in the recording, and does not work like it does in the video tutorials I’ve seen. Instead of a clean recording after the split point, I first get some unwanted “waveform” sound. Hmmm. It’s a MacBook, latest update. Any ideas? Thanks!!

So what macOS version are you running ?


Mojave 10.14.6

Yes, I think you’re right - and I think it’s a bug (I shall be logging it).

I get a short loud squelch/screech when I test on my MacbookPro with Mojave 10.14.6

a) It’s not a regression - I get the same on 2.3.2, 2.3.1 and 2.3.0 (and even on the alpha test build I have for 2.1.3)

b) This does not happen on my W10 laptop - so Windows is not affected

c) I can see that on a Mac this makes Punch&Roll pretty unusable, or at least tedious to use - it defeats the object of the functionality.

Thanks for the report choppertone - much appreciated :sunglasses:


Logged on our bugtracker: https://bugzilla.audacityteam.org/show_bug.cgi?id=2226


Actually today I have broadened out this to be a multi-platform bug.

Testing on W10 and careful examination of the resultant waveform shows that i can sometimes, but not always, get a very small glitch here too at the start of the Punch&Roll re-record.


Did you fine-tune your latency setting first, as described here? https://manual.audacityteam.org/man/latency_test.html

No, and that’s because there’s nothing on this page: Punch and Roll Record - Audacity Manual
that tells me I might need to adjust/tweak Latency.

Update: oops yes, I see, now I read more thoroughly the line that states in the tip div

It is advisable to tune the latency correction setting for your audio interface so that play-back and recording are synchronized.

That line is easily overlooked, I can make it more obvious if latency correction is really a pre-requesite for using P&R. But note carefully that the tip dive only says it is “advisable” to adjust latency - it doesn’t say it’s a necessary pre-requesite.

As a “simple-minded” user of P&R I just expect it to work out of the can …

To me it just looks look , I made a mistake, I want to start recording again from here - why would I need to bother with latency? I don’t need to bother with latency when I’m just recording my track, surely.



after long discussions on the developers email list and extensive testing (by me and others) we have decided that the Punch and Roll works as intended - but it is important (a prerequisite even) that you properly set up your latency compensation.

I updated the 2.3.3 alpha manual in a few places to make that clearer - and this enable us to close this bug as “fixed by documentation”:

You may want to read the revised Punch & Roll page:

And in particular, if you would like to try setting you latency compensation the updated page for that:

I updated that Latency Test page as when I was testing I found it tortuous to work through in its old form (and a couple of times I missed a couple of important steps as they were a bit “buried” in the text). I hope you find the revised version useful.

I can confirm that on both macOS 10.15 and W10, once I have set my latency compensation correctly, I get no more squawks at the P&R splice point.

Thanks choppertone for the report that made us investigate this and then improve the Manual - very much appreciated :sunglasses: