Reading the limitations of the trial version may help:
*The trial version of Adobe Premiere Pro CS5 does not include some features that depend on software licensed from parties other than Adobe. For example, some codecs for encoding MPEG formats are available only with the full version of this product.
7D material is MPEG based, so it does not work.
Reading that adobe page it mentions "MPEG files cannot be imported or exported" which makes sense as i couldnt import direct off camera.
But i had no issue importing files i'd converted to h264, cinepak, (mov, avi, mpg) etc, several unsuccessful attempts.
My understanding of all the codecs/filetypes/wrappers isnt that great - is an mpeg off my DSLR always an mpeg at its heart even after converting it?
If a MPEG-based file is converted to a non-MPEG format such as Lagarith, DV or Cinepak (if you want to use a really outdated codec) you can use it in the trial version. It will not be beneficial to the quality, but is a good way to circumvent the trial limitations and see if the program appeals to your workflow. The alternative is to buy the full version and if not satisfied return it within 30 days for a full refund.
Whether its an outdated codec or not is a mute point with regards to my issue of getting playback to work.
My testing is not for production work, its simply to see if I want to purchase the product (i do) and if it works on my computer (the playback doesnt, everything else does).
As mentioned ive tried multiple file types & codec combinations, these have enabled me to import into Premiere and successfully edit/clip/add effect etc but NONE allow me playback/preview - which is a pretty crucial element to editing.
Thanks for your suggestions, but i think we're on a different wavelength with regards to my issue.
Solved - sort of
Being stubborn i refused to accept the suggested reasonings for no playback.
So I installed the trial version of Premiere CS5 on my 3 year old imac (dual core, 2GB ram) to see if playback would work as intended. it's old system that is simply used as an "email machine".
It worked fine (albeit a little slow when i applied ultra key) using the exact same footage I tried and failed with on the Quad Core i5.
Im contemplating doing a complete reinstall of my OS on the weekend to see if that solves the problem on my main computer.
Brilliant, thanks Todd.
Logging in as root as you suggested was the solution, fixed the problem perfectly.
Can you talk to the boss to provide me the funds to purchase the upgrade from CS4 please