I have a mp3 player with 64MB of memory, and want to use that memory in a best possable way. Can you give me a advice wich encoder and what presets to use, to have best quality of mp3 song on desired bitrate. I have on mind a 80kbps or such bitrates, with small loses on audio quality.
It MUST be mp3 compatibile since player (Siemens SL45 built-in player) supports only a mp3 files.

Sory for my bad english

lame --alt-preset 80 or 90

You should use LAME as the encoder.
Read the sticky (at the top) threads at the mp3 forum for a list of settings and compiles of LAME.

It is good, but i have found this one is better:

lame, lowpass 15kHz, vbr, min bitrate 32kbps max bitrate 96kbps, vbr quality 9

Ogg is awesome, but it is not mp3 compatibile

This is a little unusual.

Did you confirm this with listening tests?

I used to play around with high vbr settings in order to compress div-x soundtracks, and eventually found that they sounded a little "swishy" in the high frequencies.

It is usually not advised to limit the max bitrate that way either.

Probaly only in the one single test sampel you have tried

--alt-presets have benn tuned for months (years?) by many people.
it even includes optimizations on code leve, you cannot reach with a simple commandline.

So somehow i doubt yout commmandline woulde be better overall

--alt-preset 80 would be my choice, it gives little nice files with an acceptable (for this use) loss of quality.

dev0

Sometimes I get the feeling that the alt-preset propaganda is too effective; only --alt-preset standard,extreme and insane are code-level tweaked.

What comes to the question, I'd use CoolEdit 2 Pro's MP3 encoder with these settings, rather than --alt-preset 80:
-cbr 80kbps 32khz sampling
-Max bandwidth: 14000
-Codec: High Quality Codec (Slowest)
-Allow Mid-Side Joint Stereo

FhG's mp3 vbr is no good at this low bitrates.
Lame is surprisingly good even at abr-80, but it's not quite up to FhG's quality level.

Yes, it was my mistake. I tried more tests and --alt-preset 96 sounds better.

I don't like 32kHz sampling with lower alt-presets... But I can't find a 44kHz 96kbps setting that sounds good at high frequencies.

Maybe lame, lowpass 14.5kHz, abr 96kbps , min bitrate 32kbps max bitrate 160kbps, 44kHz? This one's better than my previous one, but I can't clearly comare it with alt-preset 96k and say wich one is better...