Camtasia: What's the Optimal Setting For "Keyframes"?

[James Liberty]

First of all, what the heck are keyframes?

Secondly, what is the optimal setting to use for them? I am using the MSU Lossless Video Codec which has a default setting of 80 keyframes. Is this the ideal number?

[gmichaelh]

Hiya James,

The quick and dirty answer it that keyframes mark a beginning and ending point for something to happen in your video, i.e. the pan zoom effect in Camtasia where you zoom in on the screen to show a closer view of something. Below is a picture from a Camtasia Project I was working on, the little blue diamonds are the keyframes.



As far as 80 being an ideal number it will depend on a number of criteria. The one thing I can tell you is that the smaller keyframe number the smaller file size you are going to end up with in your project.

Hope this helped!

[James Liberty]

Originally Posted by gmichaelh

Hiya James,

The quick and dirty answer it that keyframes mark a beginning and ending point for something to happen in your video, i.e. the pan zoom effect in Camtasia where you zoom in on the screen to show a closer view of something. Below is a picture from a Camtasia Project I was working on, the little blue diamonds are the keyframes.



As far as 80 being an ideal number it will depend on a number of criteria. The one thing I can tell you is that the smaller keyframe number the smaller file size you are going to end up with in your project.

Hope this helped!

Yes, it helped. Thanks!

[LonNaylor]

Mike is correct about adding keyframes with Pan & Zoom...there is actually more going on under the covers that makes keyframes an important concept to understand when it comes to optimizing video.

During rendering, a "Keyframe" is a single frame of video where the software notes and uses ALL the pixel data. Every bit of image information for that frame is contained in the keyframe...

It then moves on to the next keyframe and gathers ALL of it's image data.

In between, the software "interprets" the difference (the delta) in data and makes guesses as to what happened and fills in the blanks with less data. This results in dramatically smaller file sizes because not all the data from every single frame is rendered.

So...more keyframes = larger file sizes (but smoother motion). That's why when you pan & zoom you actually "force" a keyframe on each end to make sure the move is more fluid.

As with everything in optimizing videos, there are trade-offs.

Less keyframes mean less pixel data and lower quality motion...

With Camtasia screencasts, understanding that less movement requires fewer keyframes when rendering can help IF you keep screen movement while recording to a minimum.

Play with the setting and see where you start getting "jerky" and you'll arrive at a good setting. Remember, each video may be different based on the amount of movement (which equals the amount of data represented in the video).

Hope this helps!

[Chris_Willow]

I think James ment keyframe settings at output.
IMHO a keyframe every 25 frames is optimal, but I'm also using "Auto" in After FX

Chris