The title pretty much says it. is there a way to make amarok ignore all my flac files and only use mp3s?

You could compile taglib without flac support - that way Amarok wouldn't recognise flac files when it builds the collection.
This is theory only - I haven't actually tried.

how would I go about doing that?

by the way I am running ubuntu.

If you don't understand what dangle is talking about, I think a better answer to your question is "no."

or instead of posting worthless things you could try to help... ?

look, you would need to read up on compiling programs on your distribution: find out what packages you need to install to facilitate this.

While I can give you a pointer to *what* you would need to do, you might have to ask on Ubuntu forums for *how*, as every distribution is slightly different. The basics are the same...
1. download a source tarball of taglib
2. extract the tarball somewhere like your home dir.
3. enter the directory you've just made and run "./configure --help", paying particular attention to the various options - look for things flac related.
4. type "make" and wait while the program compiles, crossing your fingers that there are no errors.
5. as root, type "make install".

If *none* of the above made sense, you will need to do some research. There is a lot of documentation out there.

And if you consider this useless info, please change my first reply to your initial question to "no".

That was actually very helpful. I will give this a shot. thanks.

I have found lots of instances of libtag1c2a. Would that be the same thing? it is installed by default with ubuntu,

libtag is Debian's name for tablib, so yea it's a version of taglib.

Not sure if you're still looking at this issue, but I had a thought.  It may be possible to direct Amarok to search by file extension.  I tried using .flac in the search field but that came up empty (I have many).  If you were able to search by file extension you could easily create playlists based upon those search results.

Though I am curious, why are you avoiding your flac files in Amarok?

Ok, I did a little research and you can sort/search by file type.  This makes it really easy.  I will do a write up at my blog on this in the next couple of days:

http://SoundUnReason.com/InkWell

Can amarok ignore .mp3 files?

I'll turn things around: I would sometimes like to ignore my mp3 files.
In Amarok 1.4, on can sort flac (or mp3), I don't know how to do this in Amarok 2.

instead of ignoring files it would make more sense to have format filters in the collection browser of amarok...

(yes, that's a feature request)

Here is the promised post:

http://www.soundunreason.com/InkWell/?p=673

braslau - Yes.  My post outlines using flac as an example, but you would be able to perform the exact same actions using any supported file format.

stoked - Probably not the best place for feature requests, but you may want to take a look at my post as this may be exactly what you are seeking.

Of course, one could search using type:flac (or type:mp3) under amarok 1.4, but this is missing in amarok 2.0.