Resampling effect on data folder size & # files?

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Resampling effect on data folder size & # files?

Permanent link to this post Posted by pato » Thu Nov 30, 2017 4:36 am

I use v2.1.3 in Windows 10. I recorded a project (5 mono tracks totaling about 24 minutes) at 16 bits and 44,100hz sample rate, saved the project, then resampled all tracks to 22,050hz sample rate with the intent of reducing the disk storage space used. I thought resampling would accomplish this by halving the number of samples used for the project, but instead it increased the space used from 413Mb to 476Mb. (It also increased the number of files in the folder from 430 to 542.)

Why didn't the resampling reduce the data folder size in Mb? Is it that Audacity saved all the original data recorded at the higher sample rate PLUS the resampling results at the lower sampling rate? Or what?

If resampling to a lower sample rate should reduce the disk space needed, what should I do differently? If some other procedure should be used, please explain.
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Re: Resampling effect on data folder size & # files?

Permanent link to this post Posted by steve » Thu Nov 30, 2017 1:38 pm

pato wrote: Is it that Audacity saved all the original data recorded at the higher sample rate PLUS the resampling results at the lower sampling rate?

Audacity retains data so that you can "Undo" (Ctrl+Z).
The Undo history is discarded when the project is closed.

You can also manually discard the undo history via the "History" window: http://manual.audacityteam.org/man/undo ... ml#history
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Re: Resampling effect on data folder size & # files?

Permanent link to this post Posted by steve » Thu Nov 30, 2017 1:42 pm

If a few hundred MB is a big deal, and you want to work with audio (or video), you should seriously consider getting more drive space. Just the normal functioning of the Windows operating system requires a substantial amount of free disk space to be available. Working with audio (or video) can very quickly eat up a lot of space, and if the computer is chronically short of space, then you are very likely to have problems.
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Re: Resampling effect on data folder size & # files?

Permanent link to this post Posted by DVDdoug » Thu Nov 30, 2017 3:31 pm

If you export to (regular uncompressed) WAV the 22,050Hz file will be exactly half the size of the 44,100Hz file.

If you know there are 8-bits in a byte you can calculate file size... With 16-bit mono you've got two bytes per sample, and either 22,050 or 44,100 samples per second = 44,100 or 88,200 bytes per second.

A 24 minute WAV file at 22.05kHz/16-bit/mono should be a little more than 60MB.

If you export to a lossy format (MP3, etc.) File size is determined by the selected bitrate (kbps = kilobits per second) or the quality setting. An uncompressed "CD quality" WAV file (44.1kHz, 16-bit, stereo) has a bitrate of 1411 kbps which works-out to about 10 MB per minute.
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