Comments

DavidW12 wrote on 1/25/2002, 10:43 AM
In television transmissions, "100% modulation" is measured with a pure black video signal, and the sync tip is measured to be 40 units IRE.

When video is applied, the sync level will vary depending on the amplitude of the applied video signal. Pure white is measured at 100 units IRE.

The chroma signal is separate from the luminance portion. The 3.54mHz color subcarrier contains two color carriers called the "I" and "Q". One deals with color hue, the other with color level or saturation.

The saturation cannot exceed 116 units, referenced to the 100/40 luminance/sync levels. When it does the aural portion of the transmitted signal can be affected (buzzing)as well as make the color "crawl" on the screen.

In broadcast stations, two oscilloscopes are used to measure this stuff, the waveform monitor and the vectorscope. The vectorscope deals with the color portion, showing the amplitude (saturation)as vectors starting from the center and extending out as the level increases. The hue is based on a 360 degree target where the vectors hit.

The Broadcast Color thing simply sets the color levels to not exceed those limits.
SonyEPM wrote on 1/25/2002, 11:27 AM
DavidW12 is correct.
RichMacDonald wrote on 1/25/2002, 1:34 PM
Ok, so we select "clamp" and forget about it?
Or are there other tweaks to the sliders that we should pay attention to?
SonyEPM wrote on 1/25/2002, 1:51 PM
If you add the broadcast colors filter to the project output, and select clamp, and render to DV, you'll be set, (and match bars)- no further adjustments should be needed. This does force a recompress of every frame, but the new DV codec holds up great, so no worries there.

If you want to "profile" your project for out of range colors, you can check the filter's "invert out of range colors" option, and illegal colors will be displayed with what looks like a "colored-zebrastripe" effect. You can use this rather manual process to hunt down problem areas, and apply the broadcast colors filter selectively (don't forget: clamp, no invert for render). If you have just one problem event, you could add the broadcast colors filter to that event only, and maybe save some render time.