File Sizes Not Making Sense

Audacity Help Forum Windows
1

Hi,

I just made my second SleepMachine File, made of White Noise to help me sleep, combining room heater, furnace and dish washer continuous sounds.

I edited tiny clips of a few seconds and made it 8.5 hours long. I knew the file would be massive, as I did it before with engine sounds, where the mp3 was 502mb, and the Audacity .data folder was 5.51gb.


But what is strange is with the new file, the audacity .data folder is only 156mb, but the mp3 is 479mb.

I don’t understand how it is so much smaller, when all my other audios; the .data folder is around 10 x the size of the mp3 file.

As it took me ages to make this Sleep Machine file, I would not want to lose it. Have I done something wrong?

thanks

2

Check if there are any Project Dependencies,

3

Thanks,

I did not know Audacity could do that. Is this a new feature? Or has it always been able to do that?

I checked to see if that’s what happened, but the files imported to Audacity were MP3s, so the ARE compressed. And when I changed the name of one of the files in its original location, it still appeared in the audacity file, under its original name.

I was expecting the other two files to show up, and not the renamed one. But all three audios were there.

I also checked File Dependencies, and it is set to independent.

So I’m still stumped.

4

It’s been a feature for a long time.
More recent versions (from about 2.0.0 I think), Audacity will show a warning when the project is saved if there are any external dependencies. The warning can be switched off (“don’t show this message again”), but you can always check if there are dependencies by looking in “File menu > Check Dependencies”.

Does the project include a lot of silence? Audacity projects can handle silence efficiently so they require less file space.

5

Thanks Steve,

No there is no silence. It’s continuous 8.5 hours of 3 different mp3s; (each approx a 5 second clip copied many many times).

When I did the exact same technique with 3 different engine sounds, the file was over 5gb, so I don’t get it!

6

If you are able to make a ZIP file containing the .AUP file and the _data folder and upload it to the Internet somewhere (for example sendspace.com) I can take a look. I agree that from your description there does not appear to be enough data.

7

OK thanks I will try that.

I have Dropbox already. Do you have that? Actually - you might not need to. You might be able to just go to the link.

thanks

8

I don’t have Dropbox, but I think you can make downloads publicly accessible.
Failing that, sendspace.com is riddled with advertising, but it is free to send and receive for files up to 300MB without signing up for an account (no need to fill in the From/To e-mail addresses, just upload and copy the download link address).

9

OK Steve, I just sent you a PM with the link.

thanks

10

Hi Steve,

Did you get the file?

What do you think?

thanks

11

Yes thanks I got the file.
Your guess was correct, Audacity is being clever and reusing some of the same data multiple times.
Opening up the SleepMachine3.aup file in a plain text editor, here’s the first part of the first audio track:

	<wavetrack name="dishwashercd" channel="0" linked="1" mute="0" solo="0" height="151" minimized="0" rate="44100" gain="1.0" pan="0.0">
		<waveclip offset="0.00000000">
			<sequence maxsamples="262144" sampleformat="262159" numsamples="1385522347">
				<waveblock start="0">
					<simpleblockfile filename="e000051f.au" len="144326" min="-0.64644" max="0.599908" rms="0.156431"/>
				</waveblock>
				<waveblock start="144326">
					<simpleblockfile filename="e0001fc2.au" len="158591" min="-0.64644" max="0.599908" rms="0.164283"/>
				</waveblock>
				<waveblock start="302917">
					<simpleblockfile filename="e0001ef8.au" len="158591" min="-0.64644" max="0.599908" rms="0.164026"/>
				</waveblock>
				<waveblock start="461508">
					<simpleblockfile filename="e000051f.au" len="144326" min="-0.64644" max="0.599908" rms="0.156431"/>
				</waveblock>
				<waveblock start="605834">
					<simpleblockfile filename="e000106d.au" len="158591" min="-0.64644" max="0.599908" rms="0.164283"/>
				</waveblock>
				<waveblock start="764425">
					<simpleblockfile filename="e000107b.au" len="158591" min="-0.64644" max="0.599908" rms="0.164026"/>
				</waveblock>
				<waveblock start="923016">
					<simpleblockfile filename="e000051f.au" len="144326" min="-0.64644" max="0.599908" rms="0.156431"/>
				</waveblock>
				<waveblock start="1067342">
					<simpleblockfile filename="e0001b6e.au" len="158591" min="-0.64644" max="0.599908" rms="0.164283"/>
				</waveblock>
				<waveblock start="1225933">
					<simpleblockfile filename="e0001ab6.au" len="158591" min="-0.64644" max="0.599908" rms="0.164026"/>
				</waveblock>
				<waveblock start="1384524">
					<simpleblockfile filename="e000051f.au" len="144326" min="-0.64644" max="0.599908" rms="0.156431"/>
				</waveblock>
				<waveblock start="1528850">

The relevant part of this is the simpleblockfiles:

<simpleblockfile filename="e000051f.au"
<simpleblockfile filename="e0001fc2.au"
<simpleblockfile filename="e0001ef8.au"
<simpleblockfile filename="e000051f.au"
<simpleblockfile filename="e000106d.au"
<simpleblockfile filename="e000107b.au"
<simpleblockfile filename="e000051f.au"
<simpleblockfile filename="e0001b6e.au"
<simpleblockfile filename="e0001ab6.au"
<simpleblockfile filename="e000051f.au"

The block files are the audio data files in the SleepMachine3_data folder.
Note that the file e000051f.au is used 4 times in this section.

12

OK, thanks a lot Steve.

That means Audacity is being VERY clever - if it’s made a 9 hour recording only 100mb!

This has given me an idea of how to do my songs: just copy and paste all the parts that are the same, rather than play the whole song, and in theory it should use the same bits of files!

thanks

13

Yes, but note that if you process the track in any way (for example if you amplify the track) then the project size will expand to the full size of several GBs. You could avoid that by amplifying the section before repeating it.

There’s another type of audio program that was popular in the '80’s and '90’s called a Tracker. Trackers take this approach to the extreme. A Tracker Mod file could produce hours of complex music and only be a few kB in size.