30p, 30i, 60i

[Robin Buday]

So here is an interesting situation...

I have a client that is going to be shooting 30p RED Camera footage. All of the footage is MOS so there is no concern about sync sound...

Their delivery requires HD-SR for online and BetaSP for offline.

The BlackMagic card I'm outputting from can output at 1080i30 (not 1080p30) but I have the field dominance turned off on the sequence (essentially making the output a progressive image anyway {correct me if I'm wrong}).

The HD-SR deck can record 1080i30 and 1080psf30.

My instinct would be to set the deck to record at 1080i30 to match the BlackMagic outbound signal and later use a decoder to make the BetaSP tapes from the SR masters.

My only concern is losing the progressive fields by doing it this way.

Anybody done this kind of thing before? Any thoughts/suggestions?

Thanks!

 

[Kaku Ito]

Hi Robin,

I guess you have Intensity card since it doesn't (?) do 30p.
You can place 30p footage into 60i timeline, even just leave the field dominance because there's no interlaced frames from RED anyway.

Remember to turn the frame blending off because if you use speed change then it will create interlaced frames.

I would recommend to buy Decklink HD card instead of Intensity, so you have all of the necessary formats that your clients would ask for, then you don't have to fake the format.

 

[Robin Buday]

KaKu,

I'm using the Decklink HD. I don't see an output for 30p. I see one for 30i (which I assume is some strange offshoot of 60i) and I have my 30i sequence with the field dominance turned off to throw it into progressive.

I think we're going to recommend a 60i output but I'd still like to know the logistics behind this...

Thanks for your help.

-Robin

 

[Kaku Ito]

I don't recall what are the supported format on Decklink HD but new ones support 23.976p and 29.97p. I guess there were times that they only supported interlaced format.

Anyhow, I don't think 30i is anything standard (which will mean 15 frames with 30 fields). You can get in touch with Blackmagic to find out what's going on. Hopefully, you can work on 29.97p with FCP and Decklink HD and record to HDCAM at 29.97p. That would be the best.

Sending 29.97p to 60i would just double each group of fields, so each set of fields would be identical to make the progressive picture I think.

 

[Pawel Achtel]

It doesn't matter whether you set HDCAM deck to record 60i or 30p. The way they work is that you can play it as either, depending on the material. This is why they call it PsF (Progressive Segmented Frame). There is no such format as 30i. :sarcasm:

Oh, and you probably want to do 29.97p, not 30p or 59.94i not 60i

Hope it helps.

Cheers,

Pawel

 

[MichaelP]

According to the ATSC, there is such a standard as 30fps interlace. The questions is, when is it really used?

Michael

 

[Kaku Ito]

really confusing but 59.94 with interlace is officially called 60i, but there's no such thing as really 60 frame with interlace. Panasonic call their format 30p or 60p, but they are actually 29.97 and 59.94, so just have to remember in video, there's always drop frame.

Thanks Michael, for the clarification on 30i. i never even seen it on equipment specs before.

 

[Uli Plank]

This is just a confusion about nomenclature, these are no separate formats. The EBU says the number should always state the rate of COMPLETE images, the 'i' or 'p' should just state if those images are interlaced or progressive.

To many people this is confusing, since '60' or '30' is telling them about temporal resolution. Even in Europe there's confusion about 'i25' or 'i50', but it's the same. It just get's even more confusing with drop-frame…

So, there is no separate format called 'i30', it's the same as 'i60'. If you follow the layman's logic, i30 would be 15 full frames per second, but interlaced, and that doesn't exist.

 

[Robin Buday]

I'm going to do some tests today. I'm sure we will have no trouble playing out at 60i but I will speak to our engineers and figure out a solution.

Here's what caused all this:

 

[Kaku Ito]

I'm going to do some tests today. I'm sure we will have no trouble playing out at 60i but I will speak to our engineers and figure out a solution.

Here's what caused all this:

Okay, that looks like something is conflicting with Blackmagic driver software.
Do you happen to have AJA driver installed? If you do, you have to uninstall the AJA driver.

I had experienced that having multiple drivers (in my case, MXO and MXO2, or MXO2 with MOTU V4HD) makes some of the display choices disappear from the list. Your Decklink HD supports 23.976, then there's no way it doesn't support 29.97p. Check it to find out if there's conflicts in software drivers.

 

[sebastian toro]

25p the same problem

25p the same problem

Also with multibridge pro2 we can't capture from 25p sources. Nor output for 25p. Only 50i.

we have the same doubts about this workflow.

regards

 

[Robin Buday]

Job done.

Turns out that even when you record 30p on a RED it can only be transcoded at 29.97. This was probably implemented to avoid this whole situation.