Extreme compression of audio

Windows 10, version 3.5.1

With past versions of Audacity I could compress a 5 minute audio track way down using small bitrate mp3 and changing the HZ setting to a low number. The music sounded like it was coming through a small transistor radio. Conversely I could choose a different format, change the HZ setting to a high number and create a 500 mb file out of a 5 minute audio track.

I’m interested in creating the smallest possible file to send to an artist friend via sms text message. Is there an easy way to create super small files through extreme compression? Fidelity is no concern.

Thanks to all of the developers of this program.

“Opus” format is the best for extreme compression, but check that your friend’s phone can play this format. According to this page, Opus format has been supported on Android since Android 5 (2014), but I don’t know about iOS.

Also, ensure that the recording is mono (or mix it to mono) before you export. Mono files will compress smaller than stereo.

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File size is proportional to bitrate: kbps under “quality”. If you choose a bitrate mode of “average” or “constant” you can control the bitrate and file size. Average should give you better quality because it uses more bits for hard to compress sounds and fewer bits for easy to compress sounds and silence.

kbps is kilobits per second. There are 8 bits in a byte so divide by 8 to get file size in kilobytes per second. (1)

If I’ve done my quick calculations correctly, 5 minutes is 60 seconds and you need a bitrate of 16kbps.

With constant or average bitrate, the sample rate (“Hz”) doesn’t affect file size but it might affect quality. It’s probably best to leave the original sample rate and let it figure-out the best way to compress to your desired bitrate.

(1) This isn’t an issue here, but with music files there is often embedded artwork which adds to file size, making the file will be bigger than the calculation.

Great information. Thank you.

You can down load this for free
It will compress you file to about 60% on average even more if you change the settings
The person you are sending it to will also need this to open the file
This will work out great for it allows you to preserve more of your file
and prevent lose of data
So lets say you could try a 160/24 mp3 file and reduce it to half the size
with no loss to this file…
What is great about this is you can copy this file to a folder and will always have the RAR
file to reproduce this over and over
kind of like a secured vault situation …
What is cool is that you can add foot notes to the RAR and even revisions
And name the file as you wish…
This can be sent thru E-mail

No need to install WinRar or anything else. Just use Audacity and an appropriate compressed format. As I wrote previously, Opus is the best format for extreme compression. MP3 format is more widely supported.

An alternative for Mac users is to compress to AAC from Finder, though Opus can compress smaller.

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