Me being meticulous over quality loss

I’m sure everyone is familiar with the .jpg effect that invariably occurs as an image makes its way around the internet, i.e. the obscene artifacting you see after an image has been saved and resaved and resized etc etc.

So to be terse with my question, what I’m wondering is whether doing this:
open .mp3 in Audacity
edit .mp3
→ export to .mp3
open .mp3 in Audacity
edit .mp3
→ export to .mp3
open .mp3 in Audacity
edit .mp3
→ export to .mp3

over and over will eventually result in a noticeable gap in quality between the product and the original file.

Yes, the damage adds everytime you reexport as a lossy format (eg. mp3).

So the best is to always have a lossless copy of the audio (wav or flac, for example) and do all the editing from there.

Only export to mp3 as a final step before distribution. And avoid at all cost editing and re-exporting mp3.

Some apps are able to do some basic editing (such as cutting/splitting) directly on mp3 without decoding/reencoding, but Audacity doesn’t. Audacity will always decode the mp3 and then every export you do as mp3 will add extra damage to the audio…

Other compressed formats that this applies to are WMA, Ogg, MP2, M4A, AC3 … basically any format where you see a greater than 2:1 compression ratio.
The general rule is that the more you compress, the greater the losses.
They will show this effect quite slowly if used at the highest quality settings, but the loss of quality will become obvious very quickly when higher compression ratios (small file / lower quality) are used.

Since you used the word “meticulous”, there will be a very small loss of quality (I mean, really tiny, and for most purposes insignificant) even with uncompressed data formats such as WAV, Flac and Aiff if the “bit format” is an integer type. Out of all the millions of Audacity users, someone notices and questions this phenomena on the forum a couple of times per year (which should give you the idea that it really isn’t noticeable except in extreme cases). The way to totally avoid sound quality loss when repeatedly exporting and re-importing is to export as a “32-bit (float) WAV”. This export format is in the “Other uncompressed files” option in the Export dialogue screen.

32-bit (float) files require twice as much disk space as normal 16 bit (uncompressed) files. Most other audio programs are unable to read this format, and Import/Export takes about twice as long as for normal 16-bit (uncompressed) files. In most situations, 32-bit float is considered over-kill, but the reason that Audacity uses it internally is that during the course of a project the data may be read, manipulated and rewritten hundreds of times (and you know what happens if you did that with a .jpeg file).

Audacity uses 32-bit (float) format internally, and by default the data in an Audacity Project is saved in this format, so when saving and re-opening Audacity Projects there is no loss of sound quality. However, Audacity Projects (while being a great format for production) are a really bad format for long-term storage. One tiny error in the project can turn the entire project to dust, so it is VERY HIGHLY RECOMMENDED that back-ups and completed projects are Exported as audio files rather than just saving the Audacity Project. 16-bit WAV or FLAC format is usually quite sufficient for high quality audio. FLAC has the advantage that the files are half the size of WAV or AIFF files, but are of exactly the same quality. “16-bit / 44.1 kHz WAV” is the most widely supported audio format on Earth (often referred to as “CD Quality”).

Informative posts—thanks, both of you. :mrgreen: