Nothing makes an action sequence more dynamic than varying frame speeds. Everyone remembers the amazing fight scene in The Matrix, where Neo and Morpheus do battle in the dojo. The scene was shot in several different frame rates so they could create those magical slow motion leaps, and amazingly quick martial arts sequences. But what if you want that kind of dynamic movement in footage you have already shot? Then you need Twixtor.
Twixtor is known as a "Time Remapping" program which is able to interpolate the movement of the elements in your footage, and create the 'in-between' frames when you go into slow motion, or adjust and delete frames when you want faster motion.
Here's a little further clarification for people who might be wondering what the hell I'm talking about. Let's say you have some footage that you shot on a video camera, say at 24 or 30 frames per second. You decide you want the footage to be in slow motion. You have the option in most editing programs like Final Cut Pro to change the speed of the footage, making it faster or slower. If you slow it down, you will notice the image almost trailing itself, leaving flashes of the previous frame. You will also see this effect in some movies, where they have done the same thing, such as Terminator 2 when he says, "Come with me if you want to live." This is perfectly acceptable if you like the look of it. However, in order to get slow motion without that look, such as in The Matrix or any vintage John Woo film, you would have to shoot with a camera that can handle really high frame rates, like 120 frames per second. Then you slow it down to 24, and you get the look of solid slow motion. Twixtor can give you that look, even with footage you shot at a normal frame rate.
Very easy to install, Twixtor acts as a plug-in for Final Cut Pro or After Effects. You will find it quite simple to do simple things, such as changing the speed of a clip. It gets a little more complicated as you get into changing speeds multiple times within the same clip, but after an hour of working with it you will be right at home.
One thing you will find different from just using the simple speed control on your editing program is that the clip you are working with doesn't change it's in and out points based on the speed change. You will need to do your clip resizing after you render the file, in order to get the full clip length you want.
Now, there are some tedious aspects to this program if you want to get the perfect look if you have some specific issues in your source footage. Some of these issues can be multiple objects passing each other in the frame, objects entering and exiting the frame, or stripes. The program will exhibit some small imperfections in these cases, but can be corrected by creating multiple layers of masking in Twixtor Pro.
One of the simple yet extremely effective things you can do with Twixtor is to take 30fps footage and convert it to 24fps, giving you that film look. I remember all of the effects we used to add, like layering a 90% opacity double of your footage above the identical track with a strobe effect on it. Everyone had their little tweak that could make your video camera footage look more like film. Now it's as simple as typing in the framerate.
As far as "Time Re-Mapping" programs go, Twixtor 4.5 sets a new standard. Similar programs use groups of pixels as points to interpolate from. Twixtor interpolates from every single individual pixel, giving you much higher quality details. The difference is truly amazing.
To see a very impressive example of how well Twixtor works, check out the music video sample on their page. http://www.revisionfx.com/products/twixtor/ The video was shot freeform, and speed was adjusted to match the mouths to the words of the song, and the dynamics of the shot. If you aren't sold after watching that video, check out some major productions that have also used Twixtor. For instance, Blade 2 and Driven are among some past examples.
If you ask any pro editor, they will tell you that this plug-in is absolutely essential to your system. If you edit often, I would agree. But due to it's high cost, I would adjust my recommendation to say that you should buy it as soon as you have a project that will require some speed changes. Now that you're thinking about what Twixtor can do, you'll likely find a project for it soon.
It's also worth noting that if you are a Final Cut Express user, there is a special version of Twixtor available for a reduced price, $169.95. It doesn't include all of the features, but has the same bones as the full version, at a much better price.
Twixtor is revolutionary, and can easily take mediocre scenes and add the kind of dynamics that change something from a backyard brawl into a Jackie Chan flick. It's an amazing tool for music videos, action scenes, commercials, and any other time you need to re-time your footage.