AV Digitizer Options Notes

Notice:  This software is copyrighted by Apple Computer, Inc.  You may freeely distribute this software as long as you do not charge for it and as long as this notice accompanies the AV Digitizer Options file.   This software is distributed as is and is not supported by Apple.
More legalese:  Apple Computer, Inc. does not endorse, warrant, guarantee, or make any representations, express or implied, with respect to  this software, its quality, performance, merchantability, or fitness for a particular purpose.  In no event will Apple be liable for direct, indirect, special, incidental, or consequential damages resulting from the use of this software.

Description:

The "AV Digitizer Options" extension is a "video panel component" for use with the Macintosh Quadra 840AV, Quadra 660AV and the Centris 660AV.   It provides access to several capabilities of the AV video hardware that are not easily accessed otherwise:

1.  It allows the user to switch the color space of the live video window from 16bpp color to 8bpp grayscale.  Note than in monitors with a resolution higher than 832 x 624, video will only be displayed in 8bpp grayscale.  This is a hardware limitation.

2.  It allows the user to select 1 of 7 different levels of transparency for the live video.  This means that when you superimpose a graphics window in front of the live video window, the live video can "blend" with the graphics at 7 different levels:  (% Graphics / % Video)   100%/0%, 75%/25%, 62%/38%, 50%/50%,  38%/62%, 25%/75%,  and 0%/100%.  Please note, that this feature is only available when the graphics is in 256 colors or grays.

3.  It allows the user to bypass the Inverse Gamma lookup table in the Digital Video Scaler.  When the lookup table is bypassed the video data written to VRAM will not be modified.  Note that there is another lookup table in the output end that only affects the displayed data (Not the captured video data).  This lookup table has the same Gamma correction as that of the displayed graphics.  In order to bypass that table, go to the Options dialog of the monitors control panel, while holding the option key.  Select the "Uncorrected Gamma" as the gamma table.

Installation:

Drag the file into the Extensions folder of your system and reboot the machine.  You can access the features through the "Video Settings..." menu item of any QuickTime 1.5 or higher aware application.

Extra Notes:

Presently, most video applications will stop live video playthrough when they are switched into the background.  This is because if they don't, the video will blast through any windows that are in the front.  However, the AV hardware has a dual frame buffer architecture that avoids the need for stopping the video.  Thus transparency will not work in these applications.  The only shipping application that I know that allows video-playthrough while in the background is Video Monitor, from Apple.

Bug reports, comments to:  Fernando Urbina, Apple Computer.  (Internet:  nano@apple.com, Applelink: NANO).