I have a camera made by ***. Is it compatible with DeltaVideo?

DeltaVideo uses QuickTime to receive video from a video device. This is the standard way of communicating with video devices on the Macintosh, and all known video cameras with Macintosh drivers (including USB, FireWire, serial, and PCI capture cards) support QuickTime.

If you would like to verify compatibility yourself, there is a program called HackTV, available on Apple's ftp server:


or at


It is a 15 kB utility. Try running this and see if you get video. If so, DeltaVideo will work with the video device.

I want to use two cameras with DeltaVideo on the same computer, as shown on your web page.

I'm using two USB cameras with my iMac, plugged into a powered hub, but when I select a source, it can only see one of them. When I start up another copy of DeltaVideo, while that can see the other camera, there's no picture, and then it says that the video connection has been interrupted and wants to quit.

To use two cameras on the same computer, they must have different video drivers and interfaces.

Two cameras can't both use the same driver (this would happen if using two of the same camera, or two of the same PCI cards), unless the driver has specifically been written to take this into account.

In the case of a USB camera, USB bandwidth and timing issues also come into play. Bear in mind that USB is pretty much stressed to the maximum when handling a single video stream, and doing two streams is essentially impossible, like trying to put too much water through a small pipe.

Having two independent USB ports possibly might work, as long as the above driver issues aren't present (cameras from different manufacturers). However, the built-in USB ports on Macs both share the same data "pipe" - much like a USB hub, and aren't independent.

Examples that are likely to work would be:

  • combining a USB camera and a FireWire camera or PCI capture card
  • combining a serial input camera (e.g., the old QuickCams) with a PCI capture card
  • combining Mac built-in video capture (old AV models) with a PCI capture card or serial input camera (the example shown on our website)
  • using PCI video capture cards from different manufacturers
Clicking in the Thumbnail window to view a captured frame causes a freeze.

This problem kindly was reported by a user, and possibly is caused by greater stack (a special, reserved portion of application memory) demands under OS 9.x.

The reported workaround is to disable outline style text for image stamping. We are investigating a patch to fix the problem.

I've noticed that other video-capture products have recently added a motion-detection feature - and also seem to cost less. What makes DeltaVideo so special? Don't you just subtract two images to see if motion occurred?

Frame differencing (subtracting successive video frames) is an obvious - and trivial - first step to creating video motion detection software. If that were all that was involved, then the cost disparity would seem to be unjustified.

However, DeltaVideo uses several proprietary image analysis techniques that dramatically reduce the incidence of "false" triggers, while also enabling motion tracking - which simple image subtraction cannot provide.

Most video sources possess significant noise or spurious motion that can cause excessive false triggering, especially at high "motion-sensitivity" settings. Except under highly controlled, unrealistic conditions, simple frame subtraction alone is useless, without other means of assessing motion.

DeltaVideo was the first realtime video motion-tracking and motion-detection software available on the market. It was released long before other such products became available on the Macintosh platform (and we note at least one example of which, despite overwhelming publicity by its prominent parent company, has been discontinued).

Since DeltaVideo Version 1.0, we have used our novel motion detection and tracking techniques, and continue to develop more powerful motion detection and tracking enhancements that will be unveiled in a future version of DeltaVideo. Anyone who visited our booth a few years ago, at MacWORLD Expo NY 1999 and asked the right questions, or the fortunate few who attended our Tetherless Virtual Reality press conference at that expo, can glean a hint of what's slated: technologies to appear in DeltaVideo, and elsewhere.