Sometimes Audacity skips parts of a recording. This is thoroughly described in the manual. But can I get a warning if skipping indeed has occurred sometime during the recording? http://manual.audacityteam.org/man/faq_recording_troubleshooting.html#How_can_I_record_without_small_skips_or_duplications.3F
Unfortunately I don’t think you can on Mac.
On Linux, Jack audio system reports “xruns” (buffer underrun / overrun). as does ASIO on Windows (though Audacity does not ship with ASIO support), but as far as I’m aware Core Audio doesn’t. However, it should be possible to record reliably with Audacity with no skips at all. Rather than detecting skips, you should be aiming for (reliably) not getting any.
If you need to do rigorous testing to ensure that there are absolutely no skips, then one way to do that is to record a sine wave, then in a new track, generate a sine wave of the same frequency (Hz). Then use the Time Shift tool to line up the two track so that they are exactly out of phase with each other (the generated track being an “upside down” version of the recorded track. Then adjust the level of the generated track using the track Gain slider so that the two tracks “cancel out” as much as possible. Then select both tracks and “Tracks menu > Mix and Render”. If there are no skips, then the resulting mixed track will be a quiet version of sine tone throughout. If there was a skip in the recording, then at the point where the skip occurred, there will be a sudden increase in volume level.
Thank you for your reply. (Of course I’m using the latest of everything including OS. Sorry, I should have said that. Also, I have a fast iMac.) But sometimes when I digitize a 45 minute cassette tape, the result is 40 minutes, sometimes 45 minutes, sometimes even 20 minutes. I’ve been able to find the places in the recordings where stuff has disappeared. If there are no problems on Windows, then I’l have to do this on Windows.
On modern Macs, tweaking the “buffer size” in Recording Preferences (http://manual.audacityteam.org/man/recording_preferences.html) can make a huge difference. Often it is necessary to reduce the buffer size, sometimes to zero. Unfortunately it’s difficult to predict the necessary buffer size, so you just need to experiment. The default is 100 ms.
Mm, it’s difficult experiment when Audacity more often than not is doing what it’s supposed to do and each experiment takes 45 minutes. I now tried “Recording with timer” which locks Audacity completely from using any other functions. And this time, it didn’t skip anything. Maybe that helped. (Or I was just lucky.)