The newest generation of Non-Linear Editing Software all tout their ability to deal with a variety of sources without converting. Although, they may be able to do it, when it comes to working with a variety of source frame rates, I prefer to control the choices that are made. The following principles are a guide for working in fcp7 but can also be applied to other editing software.
24 fps (frames per second) is NOT the same as 24p. 24 fps is the speed which film is usually shot at (unless you’re Peter Jackson). 24p is 23.976 fps progressive. I can go in to the why’s and wherefore’s if necessary explaining this issue. Feature films are usually slightly slowed down to 24p when transferred to a video and/or digital format.
And 30p is not the same as 30 fps. 30p is 29.97 fps progressive. Unfortunately, 30 fps is sometimes used to describe 29.97 fps.
Is that clear? If not, get used to it.
With one exception, fcp does not do a good job editing with source clips whose frame rate does not match the sequence frame rate. The one exception is editing with 23.976 fps material (aka 24p) in a 29.97 fps sequence. FCP will add pulldown without any performance issues AFAIK BUT this will not give the best possible quality. To get the best quality and control, I’d suggest converting 24p material to 29.97 adding pulldown using AfterEffects. You could also use Compressor to do this, but I’m not sure what the quality issues are. You can also output to tape using something like an AJA card to add pulldown and then recapture.
Generally, you should have your sequence frame rate match the frame rate of most of your sources. But it’s a good idea to also take into consideration your end use. NTSC DVD’s require either 23.976 or 29.97 fps material. PAL DVD’s require 25 fps. However, most PAL DVD players and monitors will play NTSC DVD’s without issue. NTSC SD broadcast requires 29.97 fps, PAL SD broadcast requires 25 fps. HD? Many systems are frame rate agnostic as long as you’re using one of the standard frame rates. If you’re delivering to a Network, they’ll usually have specs you need to meet.
There can be serious dangers in mixing frame rates in a sequence. FCP will attempt to conform your sources to your sequence frame rate, but it will not give you the best possible quality and you may have problems exporting your sequence. I also don’t think you’ll be able to media manage a sequence with mixed frame rates. And, you may get the occasional black frame in your output.
So generally, it’s a good idea to convert your source material to match your sequence frame rate before editing.
Compressor will do a great job of this if you enable frame controls and set retiming to “best.” There are some cases though where there are alternative workflows that may give you better results. If you’re editing in a 24p and some of your sources are 25 (PAL), you can “conform: in cinematools to 24p which will slightly slow down the material by just changing the metadata of the quicktime. This will only work with certain formats (prores works great) and is almost instaneous. You can also conform 29.97 to 24p or 25 but there will be a greater change in the perceived speed of the material. The change in pitch of the audio will also be more noticeable. You can adjust the pitch of the audio if necessary in SoundtrackPro.