Quality and compression
Compress audio without losing quality (or almost).
Every lossy compression involves a tradeoff, but you can make an audio file lighter while keeping sound that is still good to listen to. This guide explains how to aim for the smallest acceptable size rather than the smallest possible size, with the AudioSlim audio compressor.
Bitrate
A/B preview
Right tradeoff
Understanding loss
"Lossless" and "inaudible loss" are not the same.
A format like MP3 is lossy: it removes information to reduce size. The good news is that at a high enough bitrate, that loss becomes very hard to notice for most listening. So the realistic goal is not zero loss, but a loss your ear does not catch in the context where you use the file.
What protects quality
The settings that preserve the sound.
Perceived quality depends mostly on the bitrate, the mono or stereo choice, and the sample rate. Set well, they reduce size without degrading listening. The MP3 bitrate, mono and stereo guide details each of these choices.
The method
Find the right tradeoff with preview.
The most reliable way to compress without hurting the sound is to compare before exporting. AudioSlim lets you preview a clip so you can judge the result instead of guessing.
Start from a cautious setting
Pick a bitrate a little above the minimum, based on the content.
Preview a clip
Listen to a short compressed sample rather than processing the whole file.
Compare to the original
Watch the sensitive parts: highs, reverb, soft vocals.
Step down gradually
Lower the bitrate in steps until the last setting that still sounds right.
Keep some margin
Move up a notch if you have any doubt about an important passage.
Export with confidence
Finalize the file once you reach the right tradeoff.
By content type
The right tradeoff changes with the audio.
Spoken voice
Very forgiving: mono and a moderate bitrate keep a clear voice.
Music
More demanding: keep stereo and a higher bitrate for the detail.
Podcast
A middle ground: a polished voice without the weight of a full music mix.
Archiving
If the source matters, keep the original alongside the compressed version.
FAQ
Questions about quality and compression.
Short answers for compressing while preserving listening.
Can you really compress with no loss at all?
Lossless compression exists, but it reduces size only a little. For a much lighter file you use lossy compression tuned to stay inaudible in practice.
Which bitrate keeps the quality?
It depends on the content: speech tolerates a lower bitrate than music. The best method is to preview a clip and step down until the last setting that still sounds right.
Does preview really change anything?
Yes. Comparing a compressed clip to the original avoids exporting a file that is too degraded and helps you hit the right tradeoff the first time.
Should I keep the original file?
If the source has value, keep it. AudioSlim can preserve your originals alongside the compressed version.
Does re-compressing several times hurt the sound?
Yes. Each lossy pass adds degradation. Start from the original source whenever possible rather than from an already compressed file.
Ready to find the right tradeoff?
