Is there a new 'standard' frame rate?

I've developed in Flash for a few years and have nearly always used the default frame rate -- 12 fps -- out of a desire to maintain animation speed on slower computers, and since there's plenty of classic animation out there that looks just fine that way.

However, I'm finally starting a project that will require Flash Player 9, so we're doing it entirely in AS 3.0, and there will be no backward-compatibility issues; it's a clean slate. The site will be relatively traditional — no 3D, no wild bitmap parties — but will contain various animations of both vectors and bitmaps. Of course I plan to use bitmap caching wherever practical.

So my question is: what framerate should I use?

The arguments IN FAVOUR of a higher framerate are:
— smoother animation
— since I'll be using an AS3/FP9 combination, I can rely on the 30x speed improvement of the player over past versions, and even 'slow' computers can handle my relatively simple animations (this is 2008, after all)

The arguments AGAINST are:
— older computers aren't as fast as I'd like to think, and there are enough regular folk out there who won't see a 30 fps rate even WITH FP9
— Adobe still (as of CS3, anyway) has the default rate set at 12, so presumably they feel the lowest common denominator still can't reliably handle more than that
— since decent animation can still be had @ 12fps, and since it's hard to get reliable information on what to really expect from a broad base of users, stick with what you know works

All things being equal, it's pretty obvious that 20, 24 or 30 fps looks smoother than 12, so I'd like to use it ... all things being equal.

Any thoughts/arguments most appreciated. :)

I don't know of any "frame rate standard" but most of the people like using 30 or 31 fps. IMHO, just use whatever rate fits your project well.

It's important to note that Flash Player will drop frames if it can't process quickly enough so the obvious move is to jack up your fps to 60 or 120. However, the other side of the issue is the inherent processing that takes place in a frame (google the updated elastic racetrack article), so at 120fps, you are wasting a lot of cpu cycles on frames where nothing really happens.

According to the video industry, human persistence-of-vision tops out around 30fps, but that assumes you're working with a camera where you've got some built-in motion blur to ease the action from frame-to-frame in high motion situations. So really you need to find a sweet-spot between a nice high frame rate that looks smooth without overloading the processor. It's also worth remembering, that if you're hand-animating anything, the framerate is a direct multiplier of how much work you'll have to do.

Personally I rarely hand-animate anything, and I rely on a lot of code without a lot of animation, so I usually use 60 or 30fps. I also work with a pretty advanced user base so I can assume a slightly higher level of service.

Thanks for your feedback. Most of this project, so far as I know, will consist of garden-variety movieclip tweens, some done via actionscript and some via the timeline — but no hand-drawn animations. And I'd forgotten that the player would just drop the frames it can't display in time, so I'm thinking now that 30 should do just fine, even on slow systems.

If anyone else has anything to add, please do!

I use 30 on almost every project. Some people suggest uneven number like 31 are better, but from what I understand, that's all voodoo.