let's say someone re-encoded a 64kbps mp3 file to 128kbps.
then player shows it's 128kbps mp3 even it's 'Faked 128kbps'
then how can i know the REAL BIT RATE?

its called ears.

If not impossible, then very very difficult to do. No player I know of has this functionality.

There are some techniques that you can use to kind of infer this kind of thing. But if there was some quick easy way to check for transcoding, HA would be a better place for it. :S

[edit]

Oh, wait, never mind.

Simple. There's no way, except by using your ears as someone mentioned earlier.
What you'd want to do is avoid getting files from people, or at least keep them separate from the files you encoded yourself.

The best thing to do is only download music from people you trust...
There is a few communities of audiophiles sharing HQ music.

One of these communitys that t0m is talking about is called [censored], google [censored] to find it.

another alturnitive is to find better formats then mp3, like musepack, ogg, or lossless containers (ape,shorten,ect)

Mpc is my current fav, if u use [censored], [censored], or [censored], heres a good hash site [link removed by moderation]

[warez request censored]

Gosh, please read TOS #9:




(Emphasis and editing is mine)
The links lead to copyrighted content, I believe. So please remove them. You wouldn't want a moderator to do it for you.

Offending post censored, user suspended for two weeks. Have a nice and productive day.