Not full performance in iMovie? at DVinfo.net

Andree Markefors · April 23rd, 2011, 02:29 AM

CineForm 5.32.180
iMovie 11 on OS X 10.6.7
--------------------------------------

In anticipation of FCP X, I'm playing around in iMovie. I've often used it to quickly assemble a sequence that I then export as xml to FCP, but now I wanted to simply use it from beginning to end.

For simple projects I find the straightforwardness and simplicity delightful, not to mention that it is by far the quickest way to get through my material and export something. Add to this a well working stabilization feature and well...

However... CineForm states full iMovie compatibility (as I remember it), but my previews in iMovie (not critical) and more importantly my exported CineForm files are notably different than my source CF-files.

I know that there might be some gamma issues between what I see in FirstLight and in iMovie, but when I open up my source CF-file in QT X from the Finder (with some FirstLight corrections) this is different from the exported CF-file from iMovie that is also opened in QT X from the Finder.

This is a first generation export that should look pretty identical, no?

The exported files are brighter, at least in the sense that the shadows have been lifted. Difficult to say if the colors are shifted, due to the luminance difference.

What is the internal color precision of iMovie? Do I get 10-bit with CineForm?

Craig Davidson · April 26th, 2011, 03:15 PM

It looks like there is a gamma issue depending on the type of file being exported from iMovie. AS a test, select the CineForm codec as the output, and look at the preview frame when you change from "Millions" of colors to "Millions+". "Millions+" means use the alpha channel, which for iMovie is RGBA, which does have gamma issues.

"Millions(+)" also means 8-bit color.

We need to do some more testing to see what is being requested for the H.264 encodes, but it is also changing the gamma values.

Andree Markefors · April 29th, 2011, 08:35 AM

No difference in how the preview looks in this particular instance.

And the result is the same if I use millions or millions+

April 23rd, 2011, 02:29 AM	#1
Andree Markefors Regular Crew Join Date: Sep 2009 Location: Zürich Switzerland Posts: 81	Not full performance in iMovie? CineForm 5.32.180 iMovie 11 on OS X 10.6.7 -------------------------------------- In anticipation of FCP X, I'm playing around in iMovie. I've often used it to quickly assemble a sequence that I then export as xml to FCP, but now I wanted to simply use it from beginning to end. For simple projects I find the straightforwardness and simplicity delightful, not to mention that it is by far the quickest way to get through my material and export something. Add to this a well working stabilization feature and well... However... CineForm states full iMovie compatibility (as I remember it), but my previews in iMovie (not critical) and more importantly my exported CineForm files are notably different than my source CF-files. I know that there might be some gamma issues between what I see in FirstLight and in iMovie, but when I open up my source CF-file in QT X from the Finder (with some FirstLight corrections) this is different from the exported CF-file from iMovie that is also opened in QT X from the Finder. This is a first generation export that should look pretty identical, no? The exported files are brighter, at least in the sense that the shadows have been lifted. Difficult to say if the colors are shifted, due to the luminance difference. What is the internal color precision of iMovie? Do I get 10-bit with CineForm?

April 26th, 2011, 03:15 PM	#2
Craig Davidson Regular Crew Join Date: Nov 2008 Location: Solana Beach, CA Posts: 142	Re: Not full performance in iMovie? It looks like there is a gamma issue depending on the type of file being exported from iMovie. AS a test, select the CineForm codec as the output, and look at the preview frame when you change from "Millions" of colors to "Millions+". "Millions+" means use the alpha channel, which for iMovie is RGBA, which does have gamma issues. "Millions(+)" also means 8-bit color. We need to do some more testing to see what is being requested for the H.264 encodes, but it is also changing the gamma values.

April 29th, 2011, 08:35 AM	#3
Andree Markefors Regular Crew Join Date: Sep 2009 Location: Zürich Switzerland Posts: 81	Re: Not full performance in iMovie? No difference in how the preview looks in this particular instance. And the result is the same if I use millions or millions+