File size increases abnormally and makes Audacity useless

Audacity Help Forum macOS
1

Even with 3.6.1, file size increases exponentially when using copy/paste extensively on long tracks (30 mins or more) until Audacity becomes useless. Only solution is to export as another format (losing labels) and reimporting and starting anew.

Old bug since many years, when you paste a clip or a section from the same file to get required background silence in doing audio presentations between words, it gets to a point where file size is over 2 GB and everything breaks down.

How to reproduce:
record a 30 minutes or more of voiceover
copy a section of 1 or 2 or three seconds of background ambient sound several times along the recording (for example, to cover the breaths) or insert such silence sections if you want to render good rhythm in the narration
going ahead with the project, file size becomes to increase exponentially.

2

Maybe not exponentially, but certainly rapidly.

Every time you do an edit, make a correction, or execute a modification, Audacity makes a copy of the whole show.

If you make a mistake, you can Edit > UNDO. Audacity doesn’t try to unscramble your last edit, it just plays your last show.

We have been after the developers to let us intentionally delete the UNDO cache, but so far, no luck. There is word that they are trying to prevent that cache from getting so big so fast.

You can try Save > Save Backup Project. That will give you a frozen moment in time, Standalone Show, under a different name. Then close Audacity. That will clear the UNDO cache. Open the backup Project and keep going.

Give that a shot and post back how it goes.

Koz

3

Thank you. I don’t think it’s an UNDO problem. It’s more of the whole file inserted when I paste a short section of the file itself. Original .m4a file was 45 MB, while .aup3 file when it becomes useless is 1.7 GB.

The only way to flatten it down is to export as wav or m4a lossless and import again, losing labels.

After import, .aup3 is about 400 MB.

Regards

4

Just tried with another file. .aup3 after cuts and pastes and filters is 800 MB. Exported as .m4a lossless. Reimported: 388 MB.
Saved as backup project from the first file is still 800 MB.

My archive of .aup3 projects is very huge, and it is just a lot of memory wasted on my Mac for no reason (labels have been removed at the end of project). I will keep only the .m4a lossless, once finished.

Do you think the UNDO data is still there once I do the export as backup project?

5

I’m still experimenting with the Project Management. Short Answer: I don’t know…yet. My guess is no. It is written that UNDO goes away when you close Audacity. Stand-alone Projects with running Audacity are something of a mystery.

Here’s something I wrote under Starbucks Influence.



Audacity seems to really, really like super big sound productions because it only works internally in 32-bit Floating Uncompressed format, and it makes copy after copy of the show as you go because that’s how it does Edit > UNDO.

But that’s not the only thing that happens.

Bang! Bang! Bang! This is an uncompressed sentence.

Bang![3] This is a Lossless version of the same thing. It plays perfectly with zero damage and yet only takes between a half and a third of the space. This is a gift from the angels until you have to edit the middle Bang! Then it magically turns into:

Bang! Bing! Bang! Suddenly, no more compression, and we’re back to the original size.

MP3 (MPEG-1, Layer 3) produces convenient, tiny sound files that sound mostly identical to the original. The caution is how it does it. One of its tricks is to throw away any sound it thinks you can’t hear. There is no UNDO, and if you make an MP3 from an MP3, it does it again and you can’t stop it. By the third pass, the show may be unusable from compression distortion and damage.

Now say you open an MP3 in Audacity. The first thing that happens is Audacity converts it into uncompressed and carefully preserves all the MP3 sound damage. Then it converts it to 32-floating format to avoid any editing distortion. Then it makes multiple copies of the whole show as you edit. That can give you a monstrously large Audacity Project that is expected and normal.

Say you make it through all that and you want to make an MP3 for a client. Remember the original MP3? That damage didn’t go away. You are now on the second MP3 and if you really offended the sound angels, the client (who is a young woman) can hear the compression damage. Even worse, the client can’t make a new MP3. That’s the third one and the sound quality will be unusable.

Always do all work in WAV (Microsoft) or other uncompressed or Lossless quality. It would seem that Audacity Projects would be a natural for editing and production, but Projects can be brittle and easily damaged. Search the forum for “My Important Project Won’t Open. Please Help!”

Koz

1 Like
6

Thank you. I thought that .m4a LOSSLESS was suitable to import. Actually is native iPhone vocal memo file which I am using now.

However, my same problem happens with original recordings made by Audacity itself and saved directly in .aup3 format. File size grows bigger and bigger while I do copy paste into it, regardless of any compression or exporting action.

7

Just another try. Imported AIFF file and worked on it until it grew to 271 MB. Saved as AIFF which gave an output of 52 MB. Reimported into Audacity and saved as .aup3, it is now 106 MB. Opened old 271 MB .aup3 file and saved it as backup project: 271 MB. Nothing changes. If I do UNDO, nothing happens.

8

And then I discovered what truly happens!!!

When I paste my silence breaks from a file I use as background noise, I also put CLIPS DELIMITERS. Once I put one of this delimiters, it seems file grows in size. In fact, whan I do the JOIN ALL, and save the .aup3 file, it goes back to 107 MB as expected.

So the problems is when we do CLIPS.

Any thought about this?

9

Why are you concerned with AUP3 file size? Generally, you can delete the project file when you’re done. Personally, I’m usually doing “simple things” and I rarely save an AUP3 file (although Audacity does create temporary files.)

If you export in the same format, the resulting “final file” should be the same size as long as you don’t change the playing time.

Lossless compression is fine. And after recording, you’ve got what you’ve got.

It should be about half the size of a WAV or AIFF of the same sample rate and bit depth.

Actually, regular lossy M4A (aka AAC or MP4) is virtually immune to accumulated damage with multiple generations of compression. 100 pass re-compression test

With lossy compression the file size is directly related to bitrate. kbps is kilobits per second and there are 8 bits in a byte so you can divide by 8 to get the size in kilobytes per second (ignoring any space for embedded artwork).

With uncompressed files you can calculate file size as:

File Size in kilobytes = Sample rate in kHz x (bit depth/8) x number of channels x playing time in seconds.

Once you open it in Audacity the original format doesn’t make that much difference except for the sample rate. The AUP file size (and temporary files) will mostly depend on the sample rate, playing time, and the editing that you do.

10

Because it gets too big and Audacity becomes useless.

11

It’s one of the two and you need to be careful. You can set Voice Memo for compressed and it will produce M4A files with 10:1 compression. This can be suitable for “remember to take out the trash tomorrow.”

The other one is Lossless and can produce terrific voice files with about 2:1 compression depending on content. As far as I know, they both use 48000 Video Sample Rate. Not more normal 44100 Music CD sample rate. This can get you into trouble because Audacity can occasionally get tripped up with crossed sample rates. Say you laid your Voice Memo track into a regular music bed. Video people have been able to get away with that kind of thing forever, but not so Audacity.

See: performance duration is inexplicably off for some reason.

We also need to remember that Audacity doesn’t use a “normal” sample format in projects. It’s 32 Bit Floating. One performance is going to be different sizes depending on digital standards.

When you compare different AUP3 files, can you see the associated WAL and SHM files? All three files combined produce a stand-alone AUP3 Project File. That’s something else that can change when you close Audacity.

That’s been really messing with my Project Management Testing. I’ve had to double up my Starbucks.

Koz

12

Sometimes we can identify an operational, editing, or production problem, solve it, and the forum poster goes away happy. I don’t think this is one of those times. I think Audacity is doing what it’s supposed to do.

Do you have another application you’re looking at?

Koz

13

No, thanks. I have found the reason of this strange behavior and I believe it depends on the clip delimiters I use when pasting. This enlarges the file size.

14

I’m not sure what that is. It doesn’t appear in the manual.

Koz

15

When you paste any section you copied either from same project or another one, you can choose to paste as CLIP. Also you can choose to paste whole audio or only the selected part. If you paste as clip, the file grows hugely at each paste you do. This happens also if you set the clips manually after pasting not as clip. I don’t think it’s normal behavior. Otherwise explain to me why the project file size returns to normal when you join all the clips together.

16

We know the Developers are working on ways to keep Audacity from getting monstrously large while editing. You may be experiencing the fallout of some of these efforts.

Koz

17

I believe that when you copy/paste even from the same project or insert a clip delimiter, the application pastes also some other data that grows each time. This behavior was not present in earlier versions.