I am running Ubuntu 16.04 and Audacity 2.1.2. I would like to split a 180MB mp3 file (that is several hours of audio) into smaller chunks (chapters).

The drive I am working on has about 5GB of free disk space. However, as I import the .mp3 into Audacity, not even half way through according to the progress bar, my computer runs out of disk space, as a result of Audacity creating temporary files.

How much disk space do I need to have? It's really confusing that my disk space leaks at such a pace for a not to particularly huge file.

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    Just like a jpeg being decompressed for editing to its full bitmap & all layers and all bits, the original compressed size of the file does not matter. When an audio program uses the full decode breakout method prior to being able to edit it, it takes the full set of bits. Sooo to even attempt such math, the person would need to know: A - how many channels of audio (stereo or quad etc) B - what is the sample rate (44.1) C - what is the total lenght of the audio. There are online calculators that will do the formula easy. Or me being lasy load up a smaller similar file check usage then, – Psycogeek Jan 13 '17 at 7:52

Short answer: You'll need a lot of space.

Longer answer: Audacity always works with uncompressed audio data, so when importing an MP3 file (which is a compressed format), the file is first decoded.

Because Audacity is designed for very high quality audio processing, it works internally in 32-bit float format. This format requires double the amount of space as a "normal" uncompressed 16-bit WAV file.

Typically, an MP3 file is around 8 to 10 times smaller than the uncompressed 16-bit data. If we assume 8 times, then when decoded to 32-bit float, your 180MB file will expand to: 180 x 8 x 2 = 2880 MB.

Note that Audacity supports an unlimited number of "Undo" levels, which means that if you change the audio data, additional space is required to save the old data that allows you to undo the change. Working with audio (or video) tends to eat disk space very rapidly.

To minimize the amount of disk space required, you would do better to use an application that is able to split the MP3 without decoding it first. For example, MP3Split or mp3DirectCut.

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