Archive for August 15th, 2005

PC HDV Frame-grab How-To

Monday, August 15th, 2005

We poor schmucks without strobe lights, trained birds or 3000 feet of 35mm film might like to try some experimental photography with 1.4 Megapixel images (suitable for 4×6 and the Web, anyway) that freeze a moment in time or capture a decent picture with an uncooperative subject, or even just provide a decent web-quality photo from a video stream.

With a SONY HDR-HC1 you can get HDV @ 1440x1080i.
What you’ll need is a fast PC running Windows XP SP2 or XP64.
I’m running XP64 and some things are still a bit troublesome with Media Player 10 and HDV .wmv’s and .mpeg’s, but those issues go away if I boot into XP.
I’m sure whoever is responsible will fix it soon (either Microsoft or the video card driver folks, not sure who).

First off, plug your firewire connector (IEEE-1394) into the camera and into the PC port for it.
You may have to buy this cable, then start with CaptureDVHS and capture an HDV stream to a .mpeg file.
Then fire up Virtual Dub Mpeg-2 and slice the sequence down to just 50 or so frames (maybe less, in theory you need only 3) surrouding your image of interest.
Use an “area” de-interlace filter for Virtual Dub (you’ll need to download it — it’s a plugin) and run it on this stream, producing an uncompressed .avi output.
Then load that uncompressed .avi back into Virtual Dub, moving over to the frame you want to capture.
Then select video/copy to clipboard.
Now fire up Photoshop and do a file/new from clipboard.
Then go into Image/Resize and turn off the proportional lock.
Then change the 1440 to 1920 and you should have a 1920×1080 de-interlaced image that is 2 megapixels in size, but only contains 1.5 megapixels worth of detail.

Alternatively, the camera itself can produce 1.1 megapixel images (1440×810) de-interlaced from the tape by pressing the Photo button when you’ve paused the tape at a frame you want. In practice, this is quite hard on moving images.

A 3rd alternative is to use Pinnacle or Sony Vegas for HDV, but both are still a bit pricy for amateur photo buffs.

The images are obviously not going to compete with a D-SLR, but they’re better than NTSC frame grabs, camera-phones and web-cams.

To get images to work with, you’ll want to override the shutter and exposure control on the camera.
For birds, you need to brighten the image a little and select about 1/500th to 1/750s shutter speed or thereabouts.
This helps cut down on dark shadows and motion blur.
A tripod with a fluid head will also help, but is not essential.
Depending on your tastes, this should also work for Roller-coasters, airshows and stock-car tracks.