ACX-Check Plugin causes Audacity to freeze

Split from Audacity keeps crashing/hanging when I try to record w/mixer - #3 by Gale_Andrews

Gale, I have an issue where the ACX Check Plugin causes Audacity (and sometimes the whole computer) to hang and become unresponsive, necessitating Force Quit or a forced shutdown. It was fine when I was doing 15 minute samples, but on clips of 30 minutes or more this problem consistently arises. I am on 2.1.2, but still on 10.11.2 because I haven’t got round to making space for the latest iteration of El Capitan. Is this the right place to post this issue, or should I start a new topic?

If your harddisk is that full, you don’t need to look much further, imho.

The ACX plugin crashes because it can’t make temp files and the same goes for recording.

The rule of thumb says that you should have 20% of your harddisk free at all times, especially for audio.

Thank you. Last night I removed some files and updated to the OSX 10.11.6 which is the latest. My HD is 120 GB, so to have 20% of that free would mean around 24 GB. The ACX plugin needs that much space for temp files? If so, then I had better install Audacity on an older computer I have which has a lot more space. Thanks for the information :slight_smile:

I have no idea if the ACX plugin needs that much space for temp files. But Audacity needs it, for temp files and for “undo” purposes. And the amount needed is sometimes overwhelming…

OSX also needs free space, to defragment your files. If there is not enough space left, you’ll end up with a very slow HD since your files won’t be defragmented anymore. And especially audio suffers badly from a fragmented disk. Doing word processing you probably won’t notice.

I started a new topic for you. Even if you actually were ripping vinyl with the exact same mixer as the user in that topic, it would be very difficult to deal with two people at once in the same topic.

Given your question is nothing to with what that user is doing, the decision to start a new topic is easily made. :wink:

The problem is that ACX-Check writes the entire audio data in the selection to RAM (memory) because this is necessary to analzye it for the type of plugin it is (Nyquist).

Also at least on Mac, ACX-Check seems to use more RAM than is warranted by the audio data, which we’ll have to look into. Suffice to say on my Mac it pushes Audacity’s RAM use to 1.2 GB for a half hour 32-bit mono track and 1.5 GB for a half hour 32-bit stereo track. After you OK the ACX-Check Analysis, the RAM has to be unloaded, which could also stress the machine.

You can use the Mac’s Activity Monitor to look at how much RAM you have left while ACX-Check is running. How much RAM is installed on your Mac?


thanks Cyrano, actually I have an SSD I’m fairly sure defragmentation doesn’t apply to those. But nonetheless, it’s about time that I cleared a few GB out of that hard drive.

Thank you Gale, next time, if in doubt maybe my default thing should be to start a new topic. I’m used to the Apple forums, and those are a little bit different to these :slight_smile:

It seems to be, as you said, after OK-ing the ACX Analysis, that things really get crazy and it necessitates a Force Quit. I have 2GB of RAM, and if I am reading the right numbers, it says “Physical Memory 2GB” and under that “Memory used 1.84GB” at the time when it finally hangs. Unfortunately Apple has taken to making their laptops non-upgradeable in terms of RAM, so there’s not much I can do about it, if it turns out to be a RAM issue. As a workaround, would it work to split the clip in two and analyse each section separately? If 2 15 minute sections pass ACX, I think it’s unlikely that when joined back together, they will fail, right?

ps would it help to post the Audacity crash log here? it repeatedly mentions that it is trying and failing to load FFMpeg libraries (I’m not sure what that has to do with ACX Check, I thought FFMpeg was for something else entirely). ?

Whatever gave you that idea?

SSD’s can be a little different, depending on design of the controller, but they suffer from file fragmentation about as much as an ordinary harddisk.

Most evidence out there suggests fragmentation is much less of a problem than with HDD’s, even though it exists.

I know we are talking about Mac here, but as a reference point, Windows will defragment SSD’s once a month (which it call’s “optimization”) if you have Volume Shadow Copy (System Restore) enabled.

Windows does not let you manually defragment an SSD, as I understand it.


I think that workaround is all you have open to you.

FFmpeg is for importing / exporting extra file types.

It won’t help to post the log. You’ve simply used all or most of your machine’s RAM by using ACX-Check on a 30 minute track.


I’d say, only reply to the original topic if you’re making a comment that helps the original poster.

If you want help with your own issue, always start a new topic. Replying to two users in the same topic can get very messy, and irritating for the original poster.



oh, that helps ! Thank you Gale. I’ll note that down somewhere.

thank you. The workaround is easy enough, as long as 2 15-minute clips that “pass”, won’t give rise a 30 minute clip that doesn’t, when they are joined together. I guess the only way to find out is to try it and then submit to ACX and see what happens. Their automated validation process seems to be instant.

according to Apple documentation, OSX has automatic defragmentation/optimisation too, and it also can’t be done manually, except using 3-rd party tools.

I’d guess it’s the thousands of articles on the Internet that say that defragmenting is not required (and not desirable) on SSDs, which is only partly true, but abundant nevertheless.

Rubbish, they don’t “suffer” anywhere near as much. Yes SSDs do get fragmented, but unless the degree of fragmentation is extreme, the effect on performance for most applications is almost negligible (a notable example being Windows “Shadow Copy”). The reason that fragmentation can have such a big impact on spinning disk drives is that it can cause data to be widely scattered across the disks, so the (mechanical) read / write heads have to jump around all over the disk, which is much slower than sequential reads from contiguous data blocks. This is not the case for SSDs. Fragmentation does have an effect on SSDs due to the increased amount of metadata, the increased likelihood that data will need to be erased before write, and in extreme cases can cause data loss because there’s a limit to the number of fragments that the drive can keep track of.

SSDs work very differently from spinning disk hard drives, and the old idea of “defragmentation” has been replaced by the idea of “disk optimization”, in which reducing the number of file fragments is less important than the role played by “Trim”. “Trim” tells the SSD which memory locations may be deleted, thus reducing the overhead of garbage collection. Modern operating systems should handle drive optimization automatically for SSDs, though I think that for third party drives on OS X it must be enabled manually (unless Apple have updated that recently).

SSD may benefit from occasional disk optimization, especially when old and if regularly writing very large files. By default, Windows will run its disk optimization on SSDs once a month if Windows System Restore is enabled. In most cases you can leave disk optimization of SSDs to the operating system.

yes that was my impression. thank you.

That explains why you should no longer have to defragment manually. And that works very well, as long as your disk isn’t completely full…

Besides, the article was written in OSX 10.3 days, so I doubt they had SSD’s back then :laughing: