Differences in MP3 file size/quality...

Can someone explain in what way the quality differs between say an mp3 at 128kbs and one at 160kbs or 192kbs or whatever?

I listen to files at both sizes and have a fairly hard time telling the difference. In some cases is it just very nuanced and depending on the quality of the original recording? For instance, is there really a pressing need for my Ramones cds to be at a high quality?

I'm trying to organize my music so that it best fits on my Ipod and I'm trying to come up with a suitable compression size without sacrificing too much. I had most of them at VBR but that took up too much space so I converted most of them to 192 or 160 or in some cases the AAC or MP4 format.

But I'm not really an audiophile so I'd like a tutorial. Does the compression size affect high or low ends or what? It doesn't affect volume from what I can tell.

I went through this when I first got my MP3-ripping software. I arrived at 128kbs by ripping some songs to MP3 (at 128kbs), then recording those same songs back onto a CD-R. I then did a blind audio test, and was unable to tell the difference between the tracks on the professionally-pressed CDs and the same tracks on the CD-R.

For me, it seemed like the music recorded at 128kbs was dulled and rather "muddy" sounding, sort of like I was hearing the music in another room through a wall, or if the speakers where damped by being covered with layers of bed comforters.

Audioactive Production Studio Pro with the Fraunhofer-Radium codec.

... but I encode everything in AAC. I'll switch to Ogg when/if ever Apple updates the iPod firmware to support it.

most people are unable to notice a difference between MP3 @ 256 kbs and a CD.

It really depends on the listener: MP3 assumes what frequencies can be heard by the listener and removes the ones deemed unbearable or masked. As a result there are people who are able to identify a MP3 vs a CD in a heartbeat.


Bottom Line: don't go below 192 kbs and use a good encoder: the encoder program is at least as important as the bitrate.


Edit: I hope apple releases an Ogg Vorbis Codec for the iPod soon, as the format is superior to MP3 in numerous ways.