bad fps export, no matter what

[Nick Schlott]

“Seems to” is the key here.

What’s going on is that QuickTime doesn’t *have* a “frame rate” per se. Every frame in a QuickTime movie can have any duration. Premiere/AME take advantage of that when Optimize Stills is turned on. What this does is permit the QuickTime exporter to aggregate frames that do not change over some long period (stills, black video, etc) into one long-duration frame.

Why is this useful? Bandwidth and export speed. If you have fewer frames in a file, the file size is smaller. And if you stuff fewer frames into a file, it exports more quickly. A useful example is to drop, oh, 100 1-second still images into a timeline. Export with Optimize Stills turned on, then turn it off and export again. The former file will contain 100 frames of the correct durations. The latter @ 23.976 fps will contain 2398 frames and will export more slowly and be a much larger file.

The drawbacks of Optimize stills is as you saw some utilities will get confused about the frame rate (even Pr will in some cases, if the first few frames of the file are long-duration frames). The 100-still case above exported @ 23.976 will appear to QuickTime Player to be a 1fps file. And it actually is in some sense, but not in any very meaningful way: the video is all there and cut at exactly the times you chose. That said, some hardware players will get upset if you feed them files with a variable frame rate, so it can be important to turn off Optimize Stills for them, or if you really and truly want all those duplicate frames in your final file.

[Robert Withers]

Thanks for this explanation, Nick. I wonder if this feature has anything to do with the way that a Powerpoint presentation saved as a .mov file and imported into Pr doesn’t match the run time of the original presentation and doesn’t sync with a recorded audio track. (It’s way shorter.) But then why would Microsoft PPT save a presentation as a Quicktime file instead of an .avi? That’s what it does on my Mac.

Robert Withers

Independent/personal/avant-garde cinema, New York City

[Nick Schlott]

Yes, it probably would explain the powerpoint case: if the powerpoint .mov has long duration frames at the start of the file, Premiere will probably not be able to determine the frame rate. That’s not a case I’ve heard of, though. And powerpoint exports .avi on Mac and .mov on Windows? That sounds backwards!