Broadcast Colors doesn't adjust colors?

Gammaburst wrote on 6/23/2002, 8:12 PM
The VV3 Broadcast Colors filter successfully clamps the luminance to 16-235, but it fails to desaturate vibrant colors to comply with NTSC broadcast standards. Am I missing something? For example, drop the CYAN solid color into the timeline, apply the Broadcast Colors filter, connect a DV-to-Analog converter such as a Canopus ADVC-100, and measure the analog signal on a waveform monitor. The signal hits 130 IRE! (That appears to be the clipping limit of the Canopus box.)

Comments

BillyBoy wrote on 6/23/2002, 11:07 PM
First I doubt many have a waveform monitor to meassure analog signals. <wink>

If I remember right sometime back there was talk about something wrong with the broadcast filter in a earlier version of Vegas. You have the latest build?

Could we be talking apples and oranges? How did you drop the FX filter? If you drag it to the timeline you need to apply it to all events otherwise it only applies to the event you dropped it on. To apply globally (my term) drop on the preview window.

Did you try looking at the histograph and see if any of the bars fell in the shaded range? If so those are out of bounds.

I did try your experiment, (no analog meter) however I did notice a drop both just watching the monitor and also looking at the blue channel of the histogram. With no broadcast filter mean was over 99% with filter dropped to 91.76%.

Gammaburst wrote on 6/24/2002, 12:31 AM
It's Vegas Video 3.0a.
I sure hope SF owns a waveform monitor and vectorscope.
The histogram display doesn't show when colors are oversaturated for broadcast NTSC.

I apply the Broadcast Colors filter to either the individual clip or to the entire project - same results. I agree with your 92% measurement. The filter appears to simply clip the individual RGB channels to 16-235. That's fine for black&white, but not for color. See any NTSC television engineering handbook.
BillyBoy wrote on 6/24/2002, 9:48 AM
Sorry, don't have a NTSC Engineering book either. So I'm not going to go into the theory or discuss what the broadcast filter does or should do, I'll leave that to the SoFo guys. More to your problem, as someone with a pretty good eye, and no lab equipment you still can do lots to control output.

For example your first post brought up your concern to desaturate vibrant colors. I use the HLS FX filter and simply cut back satuation a little if need be. You can also use Color Curves.

What I would be interested in isn't your CRAN test, but rather if your video that your equipments shows out of range also shows out of range when viewed in the Preview Window looking at the various histograms.
craftech wrote on 6/24/2002, 4:22 PM
I noticed the same thing. Filter is useless.
Gammaburst wrote on 6/24/2002, 7:10 PM
Sorry, I meant that handbook comment for the folks at SoFo!
Yes, I too use the HLS filter for artistic adjustments.
The Broadcast Colors filter performs a technical function, not artistic, but it's broken.
VV3's histograms don't tell you if your movie's color saturation is out of compliance.
Chienworks wrote on 6/24/2002, 11:30 PM
Try the 3.0b update. One of the fixes in that release is to the broadcast colors filter.
Gammaburst wrote on 6/25/2002, 12:47 AM
Interesting, but 3.0b has been temporarily withdrawn.
Where did you see the list of improvements?
SonyEPM wrote on 6/25/2002, 8:39 AM
Thanks for bringing the chroma clamping issue to our attention. When an update for this plug-in is available, we'll post the download location here.