Progressive frame rate

This is my first foray into HD, so my apology for this rudimentary question.

How can I tell if an HD footage is progressive or interlaced?

I have 30min worth of HDCAM. The post house that did the transfer told me that they're 1080p25 (I have no reason to doubt them). I'm just curious if there's any way I can double-check to make sure that they're 25p and not 25i.

I imported a sample clip into FCP and looked under 'Item Properties'. I only saw the following data but no mentioning of whether it's progressive or interlaced:

Vid Rate: 25fps
Frame Size: 1920 x 1080
Compressor: Uncompressed 8-bit 4:2:2
Pixel Aspect: Square
Field Dominance: Upper (Odd)

By the way, does progressive video have a field dominance?

Thanks,

td

G5 2.3GHz Dual Core, 4.5GB RAM, 2 500GB drives, Mac OS X (10.4.4), Powerbook G4 on OS 10.3.9

Posted on May 24, 2007 6:21 AM

Reply
16 replies

May 24, 2007 11:15 PM in response to Denis Murphy

Thanks for the replies.

My mistake. It does have a codec: Uncompressed 8-bit 4:2:2. But I can't find any place that tells me whether the frame rate is progressive or interlaced.

I don't have an external monitor to check for interlacing. Chances are these footages have progressive frame rate because the post house that did these transfers told me it's progressive. I just want to double-check for my own peace of mind before taking the project online.

Is there another way to check this?

td

May 25, 2007 6:37 PM in response to Thien Do

If it says Upper field dominance then you have interlaced. Place the footage in a timeline. Set the field dominance to Upper. If you get a gray bar, meaning no render, then your footage is interlaced. If the bar is red or orange, then it needs a render, meaning it is converting the progressive to Upper. Change the field dominance back to none, and place the clip again. ( YOu have to remove the clip sometimes to get a refresh, but not always...) If you get the gray with NONE selected, then it is Progressive.

You could also just pause it in some motion area of the clip and see if you get the jaggies. That is an indication of intelacing that you won't get if it's progressive.

Usually the setting 1080p is a good indicator, unless someone manually changed the text in that window, which would be asinine, to say the least.

May 25, 2007 8:19 PM in response to RedTruck

Thanks for the detailed answer. I'm based in Vietnam and none of the local post houses have much experience in doing progressive HD since most of their work is for TVCs. I had to go to Bangkok to do the full-grade transfer (from 35mm) to HDCAM and conform in FCP. I specifically asked for 25P frame rate because this will finish in film. I wonder if they messed up (I hope that's not the case).

I just need to clarify a few things.

The reason my question came up was because as I understand it, progressive video should have no field dominance. Is this correct?

All these footages have Upper field dominance. Is this a definite indication that they're interlaced? Are there any type of HD that has an Upper field dominance?

I did a few test and got mixed result. But I'm not sure if this is because my system is not set up to do anything more than DV, and I don't have a 1080p25 Codec in my system. These are the tests I did:

Since the post house has a more recent version of FCP than I do, they gave me an XML file of the conformed project. I imported the XML, with the 'Override with setting from XML' box checked. Everything is red on the timeline, even after I changed all the timeline's settings to match the footages' settings.

However, when I create a new project, set the Sequence Settings to 1920x1080, Square pixel, Upper Field Dominance, Compressor as Uncompressed 8-bit 4:2:2. Import a clip directly into the FCP project and place it on this time line. It's gray.

I created a new timeline with same setting, except for Field Dominance set to NONE, the clip is still gray when placed on the timeline.

On the other hand, when I looked at one of the footages at full-size, frame by frame, on my Cinema display (I don't have an HD broadcast monitor), the edges look pretty sharp. For ex. I have a shot of a swish pan following a car speeding across the screen. There are some horizontal streaks in the background, but these look like motion blurs rather than interlaced artifacts. The edge of the car is sharp, with no jaggy. This seems to indicate that it's progressive.

My big worry is that the post house did the transfer (to tape) at 25P, but captured at 50i or 25i by mistake. Then again, if the Codec on the footages says Uncompressed 8-bit, then the captured footages should be the same as what's on the master tape, shouldn't it?

I'm thoroughly confused at this point. Anything that helps to shed light on this would be greatly appreciated.

I apologize for the lengthy note, but I figured it may help to give some backgrounds on the project. I need to get this sorted out before going online. This could be a very costly fix, especially since I'm paying for this film out of my own pocket. But at least if I catch it on time, I can minimize the damage.

Thanks again.

td




May 26, 2007 9:29 AM in response to Thien Do

Usually I would answer that if the clip said Upper Field Dom that is was an indicator of interlacing, but if you have a gray bar with NONE selected. . .

HD does have interlaced. It is denoted by the "i" - (1080i) and it is always upper field dominance. In fact, only DV 25 is lower field dominance. I believe everything else is upper.

I wish I had more answers for you. But if for some reason you have an interlaces video, the reason for no jaggies could be that the two fields are actually the same image repeated. See, in progressive, you still have 60 fields. Each frame consists of two fields, just like interlaced. But in progressive each field is a full frame capture. No upper and lower distinction. With a crappy one, like 720p30, it just doubles the field capture, and you have two identical fields for every frame, hence no jaggies, but stuttered looking movement. With say, 720p60, you get 60 individual fields, almost like have 60 frames. With avid you could do fields to frames and see, but FCP won't do that, I don't think.

You could also forget the project file (if there was no actual editing done) and just reimport the raw files into your own FCP project. If all they did was capture the clips, or import them, then whe cares about their project file. Open a new project, import the clips from the Finder, and see what settings show up.

But for all I know, Uncompressed has no interlacing. I have never worked with Uncompressed footage before, and I have never worked with a 35mm transfer. I worked with a 16mm transfer before I knew what I was doing, and I had it converted to DV25. Now I have a DV file of junk that once was a nice 16mm film. Live and learn.

Hope this helps. Maybe someone with more knowledge will chime in. Good luck.

Matt

May 26, 2007 9:44 AM in response to Thien Do

Hi:

This answer is based in my knwoledge in SD , but probably works the same in HD, but it's a good moment to leran it::

Set your canvas to 100% and place the playhead in a frame with heavy movement. If it's interlaced, you'll see the interlacing lines. If you don't, it's progessive.

User uploaded file

In SD setting any bellow 100% makes FCP shows just a field.

Hope that makes sense.

User uploaded file
Alberto

May 26, 2007 11:12 AM in response to Thien Do

Usually, film is shot at 24fps and when transferred to 25fps it is sped up. Film by it's nature is progressive. It's only when it's transferred to 29.97fps (US standard) that pulldown (and interlacing) is added. So I'd almost be positive that there is no "temporal" difference between fields so your material is "progressive."

Field dominance usually refers to which field comes first. Since your material is most likely progressive, and there is no temporal difference between the fields, it shouldn't make a difference.

May 26, 2007 5:28 PM in response to RedTruck

I checked with the post house that did the transfer. Evidently the frame rate they used was 50i, which I was told, is identical to 25P or technically 25Psf. The result when outputted to film will be non-interlaced. This is why FCP registers the Upper field dominance, and why the timeline is gray whether I set the Field dominance to Upper or None. This post house has done a lot of feature films with this workflow so I imagine that they would know.

I did look at a few footages with lots of movements at full-size on my monitor. They look progressive. The only time I see interlacing is when there's an odd speed change in the clips (For ex. If the speed was set at 75% or 130%, I can clearly see interlacing; but no interlacing if the speed is set at 50% or 200%).

I did a little test. I sped up a clip at an odd interval (like 165%). In FCP, I could clearly see the interlacing. However, when I captured a still frame of this footage and opened it in Photoshop at full resolution, the interlacing is gone.

I did the same thing with a clip which I know to be interlaced (PAL DV). The interlacing also showed in Photoshop.

I'm not sure if this is a definite indication that the film output will look non-interlaced, but it does help to reassure me somewhat.

Thanks again for your reply.

Thien

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Progressive frame rate

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