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Broadcast Safe and Saturation problems

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Dave Po
Broadcast Safe and Saturation problems
on Jan 27, 2009 at 6:20:09 pm

First of all, as a disclaimer, I am somewhat new to broadcast engineering stuff, but feel free to go in depth.

I recently took a project master tape in to test at my broadcasters. My video appeared to be out of color safe on their scopes. Why am I out of color range?

(random question: The scopes they where using had two diamonds, what kind of scope is that?)

I was under the impression that I was going to be legal with my colors, but for some reason I am not.

My work flow is as fallows.

I am editing SD footage in FCP.
I added broadcast safe filter last with these settings

Conservative [115] (<- should this be set to extremely conservative?)
Luminance Limiting enabled
clamp above 105
max. output 100
start (threshold) 95
Saturation Limiting enabled
Clamp above 133
Max. Output 115
Start(threshold) 105
Reduce Chroma/luma 100

Anything I should change?

From FCP I went to digibeta through an AJA IoLA.

Not totally sure what they where doing at the station, but they where upconverting it to HD. It appeared to be streaming from the digibeta and getting upconverted to HD live.

Are my non legal colors due to this upconvert in anyway?

Also, the picture that I was viewing on their color monitor (LCD) was much less colorful than what I had originally been editing. I color corrected on my computer monitor as well as using a color corrected CRT field monitor.

Why am I getting a huge loss of saturation? Is it because my colors are outside broadcast safe? Is it because of the upconvert? How can I keep my colors from look flat?



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Baz Leffler
Re: Broadcast Safe and Saturation problems
on Jan 28, 2009 at 11:26:25 pm

Did they do an initial calibration using your reference colourbars?

If you used the 'broadcast safe' filter in FCP you have to make sure it is the very last item on each clips filter list. If you add say a colour correction filter AFTER you have added the broadcast safe filter then you could have problems.

Use the scopes in FCP to check each clip etc. I use external scopes that are connected to my Blackmagic Multibridge so I know I am looking at the absolute output because sometimes the playback hardware on your Mac may not be precisely calibrated.

Baz

What would I do without the 'UNDO' button!!!!


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Dave Po
Re: Broadcast Safe and Saturation problems
on Jan 29, 2009 at 2:50:29 pm

Ya, the broadcast filter is on last, and I have checked FCPs scopes, all good.

No, they did not do an initial calibration with our bars. Is that something that they would normally do? How likely could it be that that is the problem?



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Baz Leffler
Re: Broadcast Safe and Saturation problems
on Jan 29, 2009 at 11:42:00 pm

[Dave Po] "No, they did not do an initial calibration with our bars. Is that something that they would normally do? How likely could it be that that is the problem?"

The fact that the bars you put on the head originate from the source of all subsequent output is very important. It is the 'perfect signal' travelling down the same road as the rest of your video and as it is the 'perfect signal' it is used to adjust the decks controls to make it 'perfect' when viewing on the scopes. Then all subsequent video should be correct (assuming you have made it that way).

If your signal path is not quite lined up correctly, or, the deck is slightly out of adjustment then this 'perfect signal' would take all that into account at the receiving end.

Back in the old analog days signals could vary by as mush as 25% between tapes but digital has reigned that in but there still are variances. The fact that most broadcasters specify 100% as max while but most 'broadcast' camera's output up to 105% is something that you have always gotta keep an eye on.

With your situation, they may have used their deck prior to testing your tape, and had to make adjustments for another tape and it was left that way. Thats why decks have TBC adjustments to calibrate for these little differences.

Baz

What would I do without the 'UNDO' button!!!!


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