Neither truncation nor marquee provides a good UX in general, so avoid both. Try to show as much of the info as possible, if it will be of interest to users. Even if users are checking metadata much less than once per track played, they will probably use the other parts of the GUI even less.
Some text lines will be longer than you can reasonably support, though. You would then prefer automatic scrolling (old CNN) or flipping (new CNN) in a scenario where the user avoids interacting with the player, e.g. in a car stereo, and static truncation with overlay or other means of expansion for more interactive setups.
What are the major purposes of a music player?
- Select which music to play.
- Control playback (mostly start and stop, but also skip, rewind, repeat etc., maybe volume).
- Inform about music playing (now, next, before).
Optimize your UI for (your refined version of) that.
Regarding the specific example
You’re wasting a lot of space on the progress bar and additionally have the run time (or time left) on display. Both are usually less important than title info, incl. artist. (For the album, which is also less important, you got cover art and probably a tooltip with name, release year and possibly album artist.) The progress bar, at least, often doubles as a quick seek widget – consider moving the skip buttons next to it since they provide similar functions, and also move the timer there.
Any repeat and randomize controls belong into the playlist view in my opinion, but can also be dropdowns for the play/pause button.
Is that just a mute button? I use system keys for that, but am not sure how important other people find it. You cold probably track button clicks in a beta build to analyze which ones are not needed at all or should be done differently.