The QuickTime Hints and Tips article is prepared by Chris Meyer. The first 2/3 of this article covers how to animate still images with Premiere and Photoshop.
H&T Q&A
Now comes the time in the QuickTime Forum Hints & Tips where we exchange ideas and questions. Since this is the first one (and since I╒m not into faking questions from some mysterious John or Jane Doe), I╒ll offer up a couple of other tidbits I╒ve learned so far. Feel free to send in your own.
Insoluble Dissolves;
Ever try to fade a text overlay or a still image to black, and have it never get all of the way there? Or cross-dissolve between two similar still images and have only a few pixels change? This is caused by a little quirk in Apple's video compressor (AVC). When the option to use "key frames" is turned on, this codec tries to save memory by measuring to see if there has been a big enough change between successive frames to warrant writing new pixels to the screen. During slow dissolves or fades, waiting for this "big enough change" threshold to be crossed can result in sudden jerks in the fade out, or even never making that last step to black. This can be particularly annoying with anti-aliased characters over a dark background, since the edges may already be so close to black that they never fade.
There are a couple of quick ways to fix this. One is to turn the "key frames" option off in your output options when compressing a movie--this will cause each frame to be treated as unique, instead of as just one that may have changed slightly from the previous one. This will increase the amount of memory needed for the clip, so you might want to do this only during problematic fades and splice it into a normally compressed movie later. Increasing the quality or decreasing the space between key frames are also ways to force fades to be better represented. I have also found that the Apple animation compressor treats text dissolves correctly as well.
Another trick is to add motion to the image being dissolved. The AVC has been optimized for moving images anyway, so it can handle these better. Try some of the tricks above, such as adding randomizing filters to the still image both for an extra effect and a smooth fade.
Closing the Curtain;
Those using preliminary versions of Apple╒s MovieShop utility to compress movies for CD-ROMs may have noticed a couple of problems: it stops the conversion process one frame short of the end of the source movie, and occasionally will place the start pointer in a few frames from the actual beginning of the converted movie. Apple has confirmed both of these bugs, and will fix them in an upcoming version. In the meantime, you might want to pad out your original movie with an extra frame at the end and a few extra frames at the start (especially if it starts or ends with a noticeable transition effect, such as a zoom or page turn).
There╒s another reason as well to add a couple of padding frames to the start of a movie: it appears that it takes the Sound Manager a brief period of time to bring up the volume of the audio track at the very start of playback. I have personally had problems with carefully editing the audio track to begin with a downbeat or the start of a word at the very first frame of the movie--it will preview correctly in some editing programs such as Premiere (and will actually be in the final file), but will get cut off slightly when the movie is played back through Simple Player or a similar program. Adding a few frames of silence to the start cures this, and will be a short enough of a pause that users shouldn╒t detect it on start-up.
Well, my own curtain seems to be closing for this month╒s column, so I╒ll bid fair adieu and look forward to seeing some of your own hints and tips (send them to1455 Cedar Oak Rd. Placerville, CA 95667) next issue╔
Chris Meyer has been active in the electronic music and MIDI industries since the early 80s, having worked for companies such as Sequential Circuits, Digidesign, and Roland.
He is currently the Technical Chairman of the MIDI Manufacturers Association and has personally authored many extensions to the MIDI specification. A firm believer in the "cyberpunk" ethos - that high tech on the street level leads to greater freedom and more power of individual self- expression - it's only natural that he should become attracted to QuickTime.
