iMac Rev A QuickTime Movie Playback Color Glitch Page



What is the iMac Rev A QuickTime movie playback color glitch?

For some iMac Rev A customers an issue of QuickTime movies not playing back in color has come up. The movie will play in black and white with some rainbow spectrum color banding through the middle of the playing image inside QuickTime MoviePlayer. This problem has persisted for many users with both QuickTime 3.0 and with QuickTime 4.0 and 4.1.x. Sometimes a movie will play displaying normal color in its original size only to loose its color if the user changes the size, by reducing or enlargening the image. At other times it will not play back with normal color at any size. And still again it can sometimes play normally only for the problem to reappear upon the next reboot. The QuickTime movie playback color glitch seems to be completely independent of whatever setting the monitors is set to by color depth (as in 256 colors, thousands of colors, millions of colors) and of the monitor pixel depth (640x480, 800x600, 1024x768). Some people think the problem has to do with the ColorSync Monitor Profile, but I have tested this and found the problem to be unrelated to this.

The iMac Rev A was sold with only 2MB of VRAM soldered onto the motherboard and was upgradeable to 4MB by adding a 2MB VRAM SO-DIMM or to 6MB by addition of a 4MB SO-DIMM. A full 6MB of VRAM is needed to enable the iMac Rev A to access certain QuickDraw 3D routines. How much VRAM is installed on the iMac Rev A does not seem to affect the movie color glitch, when my own iMac had only 2MB of VRAM it displayed this problem during movie playback and after I upgraded to 6MB of VRAM it persisted. That the problem was intermittent and that no other aspect of drawing graphics onto the screen seemed awry leads me to believe this is a software problem rather than a hardware defect.


Okay, but how do I tell if my bondi blue iMac is Rev A or B?

The iMac Rev A is the first iMac, released by Apple Computer in August of 1998. It's color was an aqua-marine bluish-green called "Bondi Blue" by Apple (Bondi is the name of a beach in Australia, I assume this beach must be famous for Caribbean style blue-green water). The video card on the iMac Rev A is the ATI Rage IIC_C (sometimes refered to as the Rage C+). In the Autumn of 1998 Apple released an upgrade to the iMac that included the Rage Pro, a superior video card to the Rage IIC_C. This model was called the iMac Rev B and it was also bondi blue. Subsequent iMac models from January 1999 up through the year 2000 featured the 5 fruity colors, blueberry, strawberry, tangerine, lime and grape, and then in late 1999 the graphite iMac DVSE was released. The QuickTime color glitch delt with on this page only concerns the iMac Rev A. To tell if you have an iMac Rev A the first step would be to go to the Apple Menu at the upper left side of the screen and pulldown and select the Apple System Profiler. If you are running Mac OS 8.5, 8.6 or 9.0 you should be able to see the video card type displayed under the devices tab.

A view of the Apple System Profiler displaying the video card type


If your bondi blue iMac reports that you have a Rage Pro then you have a Rev B iMac and do not have to deal with this problem. If it says you have a Rage IIC_C then read on to see how to solve the problem.


The Search for the Fix.

There is a downloadable installer for ATI drivers that Appple has called the "ATI Video SW Update 1.0." For sometime time I believed this installer could solve the problem and it did sometimes, but the problem would often creep back up on me. Reinstalling the ATI drivers from this installers seemed to work and sometimes not. It was very perplexing. The read me for the installer states that this installer is for issues with RagePro and Rage 128 cards, niether of which is included on the Rev A. The documentation mentions niether the iMac Rev A nor the Rage IIC_C card. For awhile I tried forcing an installer from ATI's own installer, intended for retail add-on PCI cards, not for the built-in cards that ship with Apple's Macintoshes. This too seemed to solve the problem sometime, but then it would come creeping along again.


Eureka!The Fix at last.

After one day when the problem came back with movie playing in black and white in their original sizes I decided to try and leave the problem alone for awhile and let my mind sleep on it. After about two weeks it ocurred to me to take a gander at the ATI drivers that come with QuickTime installers, those that come with Apple's ATI updater, and those that come with an OS 8.5/8.6 install with the original drivers that came with the specialized version of OS 8.1 that sold with iMac Rev A models. Using the "Software Reinstall" orange CD that came with the iMac I opened the disk image therein which contains an idealized setup of an iMac hard drive with everything standard installed using OS 8.1. Inside the Extensions Folder I found a group of iMac ATI drivers that differed from what is seen from other installers.

Original Mac OS 8.1 drivers for the iMac.

macos8.1_ati_drivers

ATI drivers installed by Apple's iMac ATI Software Update.

So I removed the old ATI drivers from my System Folder and dragged and copied the original iMac drivers to my Extensions Foler (OS 8.6), and reinstalled QuickTime 4.1.2. Presto! the problem was gone for good, and many games that access QuickDraw 3D RAVE functions, such as Nanosaur, UnReal and DukeNukem3D look a lot better as well. I hope this troubleshooting experience can help other iMac Rev A owners to solve their QuickTime Movie color glitch, if they have experienced this, as it was a very frustrating problem. My main reward is having found the fix and being able to share it on this webpage.


Back to homepage