i want absout the same..
But i want to limit the time for user not logged in.
For user/visiter that not are logged in as member the should only listen for 30 sec.. Members that are logged in can listen to the full song..

In sweden we dont have to pay for royalty when the songs are under 30 sec.

My english sucks and i hate google translate so i hope u undertand what i want to say

I understand what you say but I don't know if it's directly possible doable in JWplayer.
I will investigate!

That would be nice if such thing is possible.

A simpler option or alternative, might be to add an additional demo/clip field to the song page. A place where one can upload a shorter clip of their song. As well as the ability to set access levels for both the song and the demo clip.

That way one could have MC use the clip for guests and play the full song for registered logged in users.

couldn't it be done with the JWplayer API?

for instance, if a user is not logged in, have a different play handler, which checks getPosition() periodically and does seek(0) or skips to the next item in the playlist when 30 (or whatever limit of seconds) is exceeded. seeking in the controlbar could be disabled by a corresponding onSeek() handler.

that may be easier than maintaining separate demo versions of the clips. some deeper knowledge about how the player is called in muscol would help... i haven't figured out yet!

I hadn't though abou JWplayer API. it definitely would be a way to do it. the thing is you are not actually cropping the song, just the playback of it. so it wouldn't be "safe" but definitely efective.
anyway, this would require some customization work on the JWplayer JS files.

Here is an interesting article that uses the api to do just that:

http://www.longtailvideo.com/support/forums/jw-player/servers-and-streaming/12551/streaming-just-a-subclip

I would assume it wouldn't do much for copyright protection or even saving bandwidth as I would guess the whole file is still downloaded in the browsers cache. Though if everything was moved to a separate js file and just called to the page as not to be overly visible, it might at least prevent those that are not tech savvy in finding your complete song.

...and reading further down in the interesting link that greengeek has posted:

if ffmpeg is installed on your server, you can also achieve a "safer" solution where the preview clips are cached on the server. that requires even more programming work, but hints how to do it are contained in adrian.zip.