IRE setup P2, 0% or 7.5%

robot909

robot909

Well-known member
Hi, This choice is under

Camera Setup >>> setup P2 >>> 7.5%A or 0%

Which one should I use? Did some searching here, but the search strings are too short.

thanks!
 
You'll almost always want 0%.
7.5% will bring your black level up a bit, making blacks a little milky. That 7.5% is added for broadcast, but it's usually added automatically at some point in the process, so you want to make sure it's not added twice.
 
So it would only matter if you are transferring footage via composite out onto another deck?
 
You never EVER want to record ire at 7.5 on the cam ALWAYS 0 unless the cam is going live to broadcast.
 
All analog NTSC video - Composite, etc..
should have 7.5% IRE setup added. In NTSC, that's what black is. Always. Nothing to do with the look.


And conversly setup should never be recorded digitally. But it is in the HVX. (read Barry's post on the next page)

For example: A proper DV deck will assume that an incoming Composite signal has setup and will therer clip it off in the digitization. The same deck should also add setup to the composite signal when it spits it out.

There beeing said, a lot of non profesional decks don't do this for some reason. The XL1 doens't add setup, and neither does the Sony DVwalkman. Just stuff I've noticed when looking at their output on a scope. Be sure to check for each deck you are using.


But NTSC (analog) should always have 7.5% IRE setup, and Digital formats should NOT.

- Mikko
 
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ncje said:
You never EVER want to record ire at 7.5 on the cam ALWAYS 0 unless the cam is going live to broadcast.
Click to expand...

Hmm, I'll try this out today. The 7.5% is selected automatically as a default though, perhaps just to be safe (from panasonic)?
 
as per the HVX book: 7.5%A is not recorded to p2. It is added to the analog outputs and the LCD. Putting it to 0 would mean it is not added to the analog outputs. Either way it does not affect the p2 recording because no set up is recorded ( it would be relevant for monitoring to an analog monitor or recording to an analog tape deck) When using tape it does apply to the recording therefore it should be set to 0 unless it is a live feed and a few other limited circumstances.
 
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Let me clarify my answer a little too...


Have setup OFF when recording to tape, ON at ALL other times.

The camera wont' ever record 7.5% IRE Setup to P2, but it does to MiniDV (see below), you shouldn't ever record Setup to MiniDV so leave it off in tape mode.
And conversly to some sugestions, it should ALWAYS be on for any analog output. Broadcast has setup, but so do all other proper NTSC video signals, including your crappy VHS deck and EVERY monitor.

in fact set up is there BECAUSE of monitors!
At the dawn of TV & video, monitors would show black as 0%, and this ended up leaving the return scanlines of the electron beam visible on the monitor (as they are 0%. The simple (and clever) solution was to raise the level of "black" to 7.5% This was enough to ensure that the return scan (still at 0%) was "darker than black" and therfore not visible.
Once TV standards where established in europe, TV's had become of good enough quality to eliminate the return scanlines at 0% and thefore black in europe (now PAL in color) is 0%, without "setup".

There are only 2 "normal" instaces when part of the picture of a analog NTSC video signal should be below 7.5% IRE:
1) When beeing used for Luma keying. A trick using what's known as "super black" to use a level of black below 7.5% to luma key out, but leaving 7.5% above the key threshold results in a luma key where black can still be overlayed. This trick doesn't work in europe.
2) SMTPE ("NTSC") Color bars have a thin bar of 0% black down at the bottom right. There's that box of 3 near black vertical blocks in the lower right. The middle one is 7.5%IRE - the right one is brighter, and the left one is 0%. When adjusting the brightness (which is actually "setup") of a monitor, you want to set it so that the middle bar (black) *just* matches how the left bar appears - as the left is darker, the monitor will clip it at true black.


There is NO instance in NTSC when Setup shouldn't be applied to analog video. It's part of the NTSC standard and not using it is just asking for incompatibilty trouble somewhere along the way.


- Mikko ... has seen programs come in with 3 different sets of "black", with the correct one for the program beeing anywhere between 0% and 23%!
 
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The problem with just leaving setup on is that it doesn't work properly in the tape mode; it actually records 7.5% setup into the digital stream. So if you're using a DVX or an HVX in tape mode you *must* turn it off, or you'll be recording an invalid digital signal with unnecessarily lifted black levels.

If you're only working in the analog domain, and you're using the DVX/HVX as a live camera feed and recording it elsewhere (such as through a switcher and onto an analog tape system) then yes, turning setup to 7.5%A makes sense. But that's about the only case where it does. If you're recording to the camera's tape, you must set the setup setting to 0% or you'll record a digital recording with setup added, which is a mistake.
 
Barry_Green said:
The problem with just leaving setup on is that it doesn't work properly in the tape mode; it actually records 7.5% setup into the digital stream.
Click to expand...

No sh-t. :shocked:
That's *really* stupid.:furious3: - Why??
This eliminates the camera from use in an Iso-cam shoot. How could you send to a switcher and record Iso in camera (to tape) simultaniously??

Does the DVX do this too?


I'd better go back and make a few edits...


Barry, is there a negative Master Pedestal value that matches -7.5% IRE? Because if there is, you could use that to correct for having setup on.


For those that don't know, "setup" is sometimes refered to as "pedestal" as they are essentially the same thing. Though Pedestal is normally reserved for cameras and is adjustable even in good PAL cameras beacuse it alters the "look" of the image.


- Mikko ... Others 0, Mikko 1, Barry 5. Again.
 
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The DVX does it as well, yes.

Apparently it's to maintain compatibility with earlier DVCPRO products which also recorded setup. In the earliest days of transition to digital recording, apparently the engineers wanted it that way, so Panasonic gave it to them that way. Since we've now sorted out an end-to-end digital workflow we now know that we don't want setup ever recorded in a digital stream, but it's too late for them to change now.

With P2 they were able to make the break, because P2 represents a new recording medium and heck, the digital recording/broadcast issues are pretty well sorted out, so no need to record setup in the P2 recording.

But for tape, they still do.

Yes you could compensate by using the negative master pedestal, but you'll still have the same issue of the monitor not matching the recording (because a digital recording should never have setup, yet the analog monitor needs it).
 
Barry_Green said:
Yes you could compensate by using the negative master pedestal, but you'll still have the same issue of the monitor not matching the recording (because a digital recording should never have setup, yet the analog monitor needs it).
Click to expand...


Good point...

So there is in fact NO way to correctly monitor a DVX/HVX while recording to DV. Right? (Without using an external Proc-amp to add setup for the monitor/scope.)


.. or do the cameras always add (correct) setup for the Analog outputs regardless of the setting for tape? It's the only "correct" solution I can image.


- Mikko ... might be mistaken about these details of these cameras. For better, or worse.
 
Setup is only added if you tell it to.

So no, you'd have to compensate for the lack of setup somewhere near the monitor.
 
Thanks Barry, VERY good to know. Everyone should get a heads up on this one.


Barry_Green said:
So no, you'd have to compensate for the lack of setup somewhere near the monitor.
Click to expand...

... OOPS (on Panasonic's part).

Do all the Panny cams do this, or just their "proline"?


- Mikko
 
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