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YC Waveform automatically displayed in mV if I have settings set to 1080i/59.94 mode?
So I’m using Avid Media Composer 6.0 for local TV commercials and I’m finally sitting down and learning about waveforms and vector scopes.
One of the first things I noticed is that the manual says that NTSC uses IRE and PAL uses mV, yet when I have Avid in my usual project settings (1080i/59.94), it puts the YC Waveform in mV on the left side and percentages on the right. If I pop it down to 1080p/29.97, I get an IRE scale. As far as I know, there’s no way to switch the left side to IRE without leaving the 59.94 setting. Why is it doing this? Is there a way to change this?
And, to the best of my knowledge, NTSC is pretty much the irrelevant SD standard and ATSC is the new standard. That said, someone here is telling me that the difference in color-safe standards between the two is pretty much negligible and that I just need to worry about keeping the waveform below the top line and above the bottom, no matter what scale it’s using. Out of curiosity, does ATSC also use IRE?
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2 Replies
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[Adam Leonard] “So I’m using Avid Media Composer 6.0 for local TV commercials and I’m finally sitting down and learning about waveforms and vector scopes.
One of the first things I noticed is that the manual says that NTSC uses IRE and PAL uses mV, yet when I have Avid in my usual project settings (1080i/59.94), it puts the YC Waveform in mV on the left side and percentages on the right.
This is normal and expected behavior.
[Adam Leonard] If I pop it down to 1080p/29.97, I get an IRE scale.
That is surprising. I would consider that a bug. Anything using an HD frame size (720p, 1080i, 1080p) should have its video measured in mV. Are you using the last rev of v6.0.x.y?
[Adam Leonard] As far as I know, there’s no way to switch the left side to IRE without leaving the 59.94 setting. Why is it doing this? Is there a way to change this?”
It’s doing this because HD frame sizes (720p, 1080i, 1080p) have their video measured in mV, not IRE.
[Adam Leonard] “And, to the best of my knowledge, NTSC is pretty much the irrelevant SD standard and ATSC is the new standard. That said, someone here is telling me that the difference in color-safe standards between the two is pretty much negligible
Oh really? Has that person looked at the CIE diagram for ITU-R Rec.601 (NTSC, aka SD color space) and compared it to ITU-R Rec.709 (ATSC 1.0, aka HD color space)?
[Adam Leonard] “and that I just need to worry about keeping the waveform below the top line and above the bottom, no matter what scale it’s using. Out of curiosity, does ATSC also use IRE?”
Legal HD video signals are not supposed to exceed 700mV (peak) or drop below 0mV (black). Scopes usually range from -20mV to 730mV. Will an occasional excursion above or below get you rejected? That depends on how tight the QC is where you are delivering.
ATSC 1.0, aka HDTV, uses mV, not IRE.
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Jonathan S. Abrams, CEA, CEV, CBNT
Apple Certified – Technical Coordinator (v10.5) Support Professional (v10.6 through v10.9)
Chairman, NY section, AES -
Thanks for all that. I’ve copied some of the most important things you said into my notes. I’ve never had anything rejected by QC here, so I’ll just worry about keeping things between the lines for right now.
We’re using Avid Media Composer 6.0.1.1. My predecessors at this job apparently didn’t care to update the software, even the bug fixes. When I looked into doing it, I learned that you can apparently only be so far behind on patches before they require you to fully uninstall the software and reinstall a newer version, which I considered far too risky. My employers agreed with that.
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