Broadcast legal

[Michael Bendixen]

We're submitting to PBS and just want to double check some of the current video level requirements.

For while we've been used to a standard of 0% to 100% (0-700mV) for white levels and -20 to 120 for peak chrominance.

What I'm confused on that chrominance and luminance seem to not have separate specs (see below)

2.2.2 Producers should be aware that the GBR gamut will be hard limited
(“legalized”) to the 0 to 700 millivolt range when the final PBS package is created
for distribution.

I think that "GBR" refers to the composite in the conversion from Y'CBCR to RGB.

Should I be hard limiting everything to 0-700mV?

I guess I don't understand--because we have the tektronix external scope and the double diamond has always been set to 120.

Any tips?

Thanks,
Michael

[Bryan Cantwell]

Here's some relevant info, hope it helps...

The luminance level in black areas of the program must fall as low as 0%, but not below 0%. Objectionable black clipping must not be evident. Black setup is not allowed in any digital submissions. When measured as derived composite signal, the black level must not fall below 7.5 IRE units.

The luminance level in white areas of the program must reach as high as 100%, but not above 100%. Objectionable white clipping must not be evident. When measured as derived composite signal, the white level must not exceed 100 IRE units.

Derived standard definition NTSC peak chrominance plus luminance gamut must not exceed 120 IRE when measured with a flat filter on a digital waveform monitor. Component digital derived GBR values must remain within the legal gamut of 0-700 millivolts.



The allowable color gamut (range of values) for GBR signals in NTSC is 0-700 millivolts for Green, Blue, and Red. Serial digital 601 signals provide a Y Cb Cr component signal that can contain invalid colors when converted to GBR. Signals outside the GBR gamut range may lead to clipping, crosstalk or other distractions in encoders and other processing devices designed to operate within the legal gamut.

All G,B or R signals should lie inside the range -10 millivolts and 720 millivolts after an IRE filter has been applied. The resulting composite luminance signal should lie inside the range of -1 to 103 IRE. A diamond arrow or equivalent display should be used to detect illegal gamut levels.

Programs with GBR Upper Gamut levels above 735 millivolts; and GBR Lower Gamut below -50 millivolts will be rejected and returned to the program producer for correction.

GBR gamut should be “legalized” to the -10 to 720 millivolt range prior to submission.

[Michael Bendixen]

Thanks for the reply Bryan--

I had a few questions:

>>When measured as derived composite signal, the black level must not fall below 7.5 IRE units<<

I thought 7.5 IRE is a legacy of NTSC/SD video. I only work in percent now. For example don't go below 0%

>>Derived standard definition NTSC peak chrominance plus luminance gamut must not exceed 120 IRE when measured with a flat filter on a digital waveform monitor. Component digital derived GBR values must remain within the legal gamut of 0-700 millivolts<<

Same thing--I'm just dealing with HD. Have you seen updated information for above in HD?

>>GBR gamut should be “legalized” to the -10 to 720 millivolt range prior to submission<<

Same thing--HD or SD. That's where we have our double diamond scope set to now--but it's not written in the PBS specs--hence my confusion.

Thanks!
Michael

[Bryan Cantwell]

Question. Are you delivering to APT or a local affiliate?