Fixing Sorenson 3 Pro transition bug

Wednesday, December 21, 2005

Is your Flip half flipping? Experiencing Drop stop? Having problems with your Dissolve only partially dissolving? You’re not alone (If you haven’t seen it, it looks like someone’s thrown a wood block into your screen to keep your transition from playing all the way when exporting as a QuickTime movie). We’ve seen this several times before and have determined what may be the cause of your malady if you’re using the Sorenson 3 Pro codec.

Using the Sorenson 3 codec means that your viewers only need to have QuickTime 5. Having Sorenson 3 Pro opens you up to many more compression options, but it also defaults the problem option, bidirectional prediction, active. Briefly, this is the little piece of magic that allows a Sorenson coded .mov to play backwards as smoothly as forwards (for allowing your viewers to cue/review smoothly like a DVD player). This is wonderful for regular movies, but, since this type of frame creation is not what Keynote expects, it causes a problem when the frame doesn’t line up with Keynote’s sprite track. All you really need to do is just turn it off, but, since you won’t find Sorenson in your System Preferences, we’ve mapped out how you get TO it in order to DO it.

You can do this with most any program that exports QuickTime (strangely, except for Keynote) but to make sure we’re all on the same page, we’ll use the QuickTime Player. Open the QuickTime Player then open a movie (you need to go into the Export options and you can’t get there without having media open).

Change the Export popup menu to Movie to QuickTime Movie and click the Options… button.

Now you should be in the Movie Settings window. In the video area, click the Settings… button.

In the Compression Settings sheet, click the popup tab at the top and choose Sorenson Video 3, then click the Options… button.

And what do you know, we’re here!

Set B-Frames
The Sorenson settings open up to a nice Summary screen which should show your problem right there.

You’ll see that Use B-Frames has a check beside it. Since this IS only a summary screen, we’ll need to go to the Encode tab to turn it off. Where Bidirectional Prediction: shows Allow, click this and change to Off,

then click OK.

This will take you back to the Compression Settings sheet. Since our change was OK’d in Sorenson’s preferences, you don’t need to click OK in the windows that are still open, so just Cancel your way back to the movie and quit the QuickTime Player.

Now you’re free to use Sorenson as much as you like without having to worry about incomplete transitions. If you need this feature for other movie exports, DON’T forget to go and turn it back on after working with Keynote.