File Sizes Not Making Sense

[steve]

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:

Code: Select all

	<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:

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<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.

[Fabbelle]

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

[steve]

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

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.