slow preview icon generation?

Leopard does "remember" the previews and I don't experience the problem you describe, but then I never turn my computer off. Could it be that you are seeing the problem after rebooting?

The Finder does remember the previews (a.k.a. Thumbnails) for two days of inactivity. So if you go to a folder once it will generate a thumbnail for the files in that folder. If you don't go back to that folder within 2 days, it will purge the cache of that thumbnail. Every time you go back to that folder, after the thumbnail has been created, resets the clock (so to speek) and it waits another two days before purging the thumbnail for that file. If you quit the Finder, all thumbnails are gone.

It sounds like your movies are HUGE!!! Check in the console, see if there is any spew from quicklook saying it timed out. That could explain the slowness, and how some of your thumbnails don't appear, and is a bug in quicklook not the Finder.

One thing you could do to speed things up is open one of your movie files, copy a single frame from it to the clipboard, paste it into something like Photoshop, crop it to 128x128 (or 512x512) and save it as a jpg. Then open that jpg file and copy its contents to the clipboard, then open an Info Window to that file, click on the icon in the upper left corner of the window and press Command-V to paste the image onto the file as a custom icon... There is a bug where the custom icon, after being pasted doesn't always show up in the Finder windows (but it does show up in the Info Window), if you quit/relaunch the Finder it will appear. Custom Icons trump OS generated thumbnails, so if the file has a custom icon the Finder won't try to create a thumbnail for it. Doing this would probably speed up your entire OS because the Finder and quicklook won't be chugging along trying to process your movies every time you open a folder to it.

Hope that helps.

If it really bothers you, you could turn of icon thumbnails. In each view style, press Command-J and uncheck the "Show Icon Previews" checkbox. Then press the "Use As Default" button to make all windows in that view not show thumbnails.

Oh yeah, I was wrong. You don't need to crop the image to create the custom icon. Just copy it and paste it in, the Finder will scale it down for you. You can also setup a Automator script to do this for you if you like.

Karptonite wrote:
It sounds like the only solution is creating single frames one at a time, hardly worth it for a preview.

I think there may be some confusion here about previews & movie "poster" frames. Most of the movie file "container" formats provide some means to designate a single frame of the movie as its preview or poster frame, but the details differ greatly: some formats support multiple, pre-rendered images, or even images compressed with a different codec from the movie itself. Many movie files just contain a pointer to some frame of the movie, which may or may not be a key frame, & thus may require considerable codec activity to reconstruct it for preview purposes.

"The Finder does remember the previews (a.k.a. Thumbnails) for two days of inactivity"


This makes the Finder icons unusable for a pro photographer. Just opening a folder with 3-500 60Meg tiffs in icon view takes forever.

The alternative to have embedded icnons means that coverflow/quicklook doesn't work right

The 2-day cache ought to be adjustable by the user.