Bugzilla – Bug 2226
Punch&Roll record inserts a squelch/screech noise at start of re-recording
Last modified: 2019-10-15 11:14:09 UTC
This was originally posted as a Forum report: https://forum.audacityteam.org/viewtopic.php?f=47&t=107077&p=378426 Both the OP and myself are on Mojave 10.14.6 - I do not recall this happening on earlier versions of Mojave when I was testing Punch&Roll when Paul initially introduced it (so it may be a Mac change that has made this happen). 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. I have logged this as P2 so that it remains as at the RM's discretion as to whether or not we release with this - but for me I think this is marginal P1
Created attachment 866 [details] Punch&Roll Glitch noise amplified It's also a bit moonphasey in its recurrence -but certainly repeatable at times. After resetting my audacity settings folder it was harder to observe. Now I only get a small glitch-noise - but the image shows it amplified by 29.01 dB to show the nature of the "noise" (but this is more like what I was seeing, and hearing, when I first reported the bug)
Created attachment 867 [details] Punch&Roll Glitch noise no amplification - louder source So I tried again, this time with louder more realistic source material (a song I recorded off-air). This gave a loud squawk (clipped as I observed later by turning on Show Clipping) - and as the OP observed this sounds like a distorted made louder snippet from the existing audio
Created attachment 868 [details] WAV file of the P&R squawk - with brief surrounding audio This is a WAV file of whet the squawk sounds like - you can play it and/or load it into Audacity to look at.
Created attachment 869 [details] WAV file of the P&R squawk - with brief surrounding audio WAV file of the P&R squawk - with brief surrounding audio
Created attachment 870 [details] W10 P&R glitch amplified Testing again today om W10 with audacity-2.3.3-alpha-353-cff0011ee40dba6aa2e749ab99ea4efa57736796 Examining the waveform very carefully I can now see that on Windows too I also get a small glitch noise just after the re-record starts on Punch&Roll Record. It is very small and like some of my Mac tests it requires a 38 dB amplify to show its nature - looks similar to the glitch waveform I see on Mac. The attached image is the glitch amplified by the 38 dB Accordingly switching this to All platforms
One thing I note (testing on W10) which may be relevant 1) When P&R starts the first thing it does is place a clip market at the edit point 2) Then the audio to the right of that clip point is deleted 3) then the preview plays By recording silence as the repair I note that close examination of the waveform shows that after the clip there is a consistent 0.10 second fade of the audio (I assume this is intentional to avoid a click) I don't know if this has any bearing or relevance - but I report it it just in case.
Easily reproducible (with a normal song) on 2.3.3 alpha jc010 running unfer macOS 10.15 Catalina.
P2 -> P1 per Paul's request.
Following discussions on the dev email thread wher we agreed that latencty correction is a prerequisite for making Punch&Roll work properly - I think I've made sufficient changes to the 2.3.3 alpha Manual to be able to mark 2226 as fixed by documentation: 1) https://alphamanual.audacityteam.org/man/Punch_and_Roll 2) https://alphamanual.audacityteam.org/man/Latency_Test I still think that an additional FAQ for Squawky P&R may be a useful addition - but I don't think I have time for that today. Tested with latest alphas on W10 and macOS 10.15 Catalina
