Windows XP and webcams/dv

At some point a few weeks ago, my webcam mysteriously stopped working. My wife and I use Hello heavily, so the inability to get the camera to work was a major bummer. No matter what I did, I always got “creation of video preview failed”, and several of the applications that used the camera were now crashing! Even more maddening, one application was still able to get video from the cam: Microsoft Messenger. But I don’t use it!

I tried all of the magic incantations I could think of to get it to work:

  1. Uninstall/Reinstall drivers
  2. Uninstall/Reinstall drivers, from Safe Mode
  3. Uninstall/manually delete and purge/Reinstall drivers
  4. Reinstall DirectX
  5. Swap for another webcam
  6. Uninstall DirectX 9/Revert to DirectX 8
  7. Uninstall/Reinstall video drivers
  8. Uninstall video, cam, and TWAIN drivers/manually purge them all/Uninstall DirectX/manually purge DirectX/reinstall each

Still no joy. I started trying some stranger incantations:

  1. Found this usenet post about digital video cameras having a similar problem and needing to unregister and reregister the qdv.dll file. Nope.
  2. Tried looking for DirectX9 installer command-line switches, hoping for a “reinstall all files”-type option. Nope. But I did find this MSKB article.

Just as I’m hitting the BACK button, about to give up … I notice that at the bottom of the page there are a bunch of “qxyz“-named files.


Digital Video.

What else is in the list?

qcap.dll. Capture? Cam?

Sure enough, a quick “regsvr32 /u qcap.dll & regsvr32 qcap.dll” later and I suddenly have video again.

Categorized as Random

By Rick Osborne

I am a web geek who has been doing this sort of thing entirely too long. I rant, I muse, I whine. That is, I am not at all atypical for my breed.