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video de-interlacing with Vegas
experience level: intermediate -
you've shot a couple of film or video projects
There has been a great deal of excitement
about progressive video. Several new cameras have arrived on the
prosumer and professional scene that acquire imagery as whole frames
(30p & 24p) rather than the interlaced fields (60i) of traditional video. For those
confined to older standard-definition cameras with 60i acquisition, there are a variety of post-production de-interlacing
solutions available.
I've shot a variety of narrative short films acquired
on standard definition video. Of the cameras I have used, I most
prefer the color rendition and contrast latitude of my JVC GY-DV500 over
the pro-sumer choices including the Canon XL-1 and the rabidly popular
Panasonic AG-DVX100. The DV500's 1/2" 3-chip CCD block, pro
form-factor, and manual lens provide me the creative control I need.
Unfortunately, my GY-DV500 is a
60i camera.
Fortunately, I have
Sony Vegas 5.
I employ a simple de-interlacing process
using Vegas 5 from Sony (formerly Sonic Foundry) that effectively creates 30p video from a 60i source.
This article is confined to the
60i/30p domain and does not address 24p. Nor does it address 16:9
although this procedure may be applied to widescreen and high-def
interlaced footage as well.
Below,
are links to some sample frames from the short film
The Real You. I've
chosen samples from a single handheld shot that included hard pans as
well as moments of rest. The full-size frames are pixel-aspect
corrected and widescreen crops from the original 720x480 camera source.
panning camera samples
static camera samples
The Vegas multi-step procedure is as follows:
1.
Place the 60i source on the Vegas timeline.
2. Open
Vegas Options (Alt+Enter) and choose "Interpolate" from the de-interlace
option.
3.
Export to a 30p uncompressed DI (digital intermediate) file.
(Careful, it's big!) You will need to create your own preset since
one doesn't come with the Vegas install.
4.
Place
the 30p DI onto the Vegas timeline above the original 60i clip.
5. While
comparing the 30p to the 60i (by muting/unmuting the 30p track) add a
Sony Sharpen filter to the 30p footage and adjust to taste. I've
typically started with a setting of 0.5.
6. Open
Vegas Options and change the de-interlace option to "None" and
export the sharpened 30p footage to the file format of your choice.
Instead of the Sony Sharpen, consider the Unsharp Mask or
a Convolution Kernel method.
Since the sharpening process potentially adds noise
(although not more than originally existed in source footage)
consider a noise-reduction pass with something like Grain Surgery or a
Convolution Kernal method.
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