3 Replies Latest reply on Mar 7, 2009 11:33 AM by Mylenium

    Alpha channel from Quicktime into AE - broken.

      This has been driving me nuts for some time. I am generating an animation w/alpha channel from my 3D software (FormZ.) It creates a proprietary .fan file containing the animation frames, which is then converted to Quicktime. I am using the animation codec, max quality, millions+ colors. When I import the QT file into Aftereffects, I get the alpha channel pop-up - so it apparently recognizes that something is there - but whether I choose straight or premultiplied, I just get black for the alpha channel with jaggy edges.

      This is on OSX 10.5.5, QT 7.6, Adobe CS4. I have had the issue dating back a year or two, I had thought it was a bug that would be fixed by now - the same process used to work fine with older versions of AE and QT.

      Now - the kicker - when I boot into Windows XP and do the QT (7.5.5) conversion there - then take it back to OSX for import into AE - THE ALPHA CHANNEL WORKS PERFECTLY.

      I have talked with FormZ in the past, they recognize and have duplicated the problem. However, it is apparently a Quicktime issue so there is not much they can do about it.

      This seems like a pretty fundamental issue that I can't believe it would go uncorrected for so long. Why would the Mac version behave differently from the Windows version? Am I completely missing something in the Mac QT? I have played with the various transparency settings under Movie Properties (QT Pro) - but all I get is a dithered mess when I try to change those settings and bring it into AE. I can't even find much discussion of it - I found a reference to Quicktime 7.1.5 breaking alpha channels, but nothing very specific.
        • 1. Re: Alpha channel from Quicktime into AE - broken.
          Mylenium Most Valuable Participant
          Well, but what is the structure of a *.fan file? The way I see it, it simply contains invalid values, which may cause QT to flip out. Since it uses bits and pieces of accelerated functions on the Mac (you know, that CoreImage/CoreAnimation/FXplug stuff) I could quite well imagine that some shared library causes a conflict when propagating the channels to the streams. I wouldn't attribute this solely to QT. Even though Apple have made a mess of it over the years, this is certainly a combination of circumstances, and core functions should work... Are there any notable discrepancies when you view the extended properties of the QT files? what do other tools say about the files' Alpha channel?

          • 2. Re: Alpha channel from Quicktime into AE - broken.
            Level 1
            Thanks for the reply. I can't find any difference in the extended properties between the Windows and the Mac version of the QT file. Under Visual Settings - Transparency tab they both say None (allow dithering.) I tried importing the clips into Premiere, with the same results. (Windows clip shows the Alpha properly, Mac clip does not.) Unfortunately I don't have any other 3D software on the Mac to try and generate something else with an alpha channel. I could probably track down some other ways to troubleshoot, but I don't do video on a daily basis, so I don't have access to a lot of other tools.

            I guess I am placing the blame on Quicktime, since I am pretty sure the .fan format has not changed, and the conversion -used- to work fine on the Mac. As far as I can recall when I first noticed the issue, it was after a system update. (ie, my version of FormZ did not change.)

            I'm sure it is possible that Apple did not technically "break" anything, they just changed something on the Mac side that FormZ has failed to implement. I will follow up again with FormZ, but I am hoping someone else here may have noticed a similar issue using other software. Unfortunately it seems there aren't a lot of people doing 3D animation on the Mac these days.
            • 3. Re: Alpha channel from Quicktime into AE - broken.
              Mylenium Most Valuable Participant
              Ah, I see. Might have something to do with the change of the CoDecs to "legacy" status during the 7.x QT cycle. if you are looking for another 3D tool to test - you can download Cinema 4D R11 and "activate" the demo, so it runs for 3 weeks without limitations. And of course Blender is still free. If you can provide some of those *.fan files along with a clue as to where I can find the conversion tool, I might give this a spin and cross-check on my MacBook Pro.