Progressive VS Interlace

[Randy Johnson]

What is the "Visual" Difference between the two?

[Chris Harding]

Hi Randy

Progressive is supposed to have a higher vertical resolution but I have yet to see it in practical terms.
If you shoot 50i then remember your NLE must de-interlace the source footage before you edit ..In Sony Vegas that's in project properties.

You could probably see a tiny difference in full HD on a big screen TV so maybe go for 50P if you are delivering on BluRay ... I have yet to see any difference on a DVD. In fact I did a test with 1920x1080 in various shooting formats and then rendered each identical clip to MPEG2 (I even tried native and transcoding down to MPEG as well and on a 42" TV they all looked stunning and no visual difference.

If you have a really big TV .. try a 1920x1080 clip done in both 50i and 50P and watch it direct and there is a chance you will spot a resolution difference. I have never tried that test as my TV has no USB input and I don't have a BD player .... On a media player USB rendered down to 1280x720 there was no difference between I and p in my opinion but you might spot it at full HD on a big screen.

I have been with brides watching on a HUGE TV straight from DVD (SD 720x576) and we were both amazed at the quality (that was shot at 50i) so I just don't bother.

A test and comment from others would be interesting to watch!

Chris

Chris

[Bruce Watson]

Originally Posted by Randy Johnson

What is the "Visual" Difference between the two?

As Chris notes, there is some resolution difference. What I find annoying about interlaced video is the combing artifacts. My progressive TV doesn't do a very good job of deinterlacing. I also see some interline twitter (flickering) on occasion, but it's always a transient problem.

[Ron Evans]

Temporal motion of interlace and progressive is the same ( 50i/ 50p or 60i /60p ) the camera is taking the same number of exposures .Don't get confused by the timecode designations. For interlace the camera records fields ( either odd or even half the vertical resolution) for progressive the whole frame is recorded. So the motion is the same for both. Bluray at these rates is only interlace the only progressive for Bluray is 24P or 1280x720 progressive. I see no differenece playing back from the camera, progressive or interlace from my NX30U to my Sony 240HZ interpolating TV since the TV corrects fully for the interlacing. Older TV's with poor deinterlacing there will be a difference. If you are delivering on DVD or Bluray then interlacing is the format unless you like the slow frame rate film look. All the NLE's allow for interlaced or progressive input and normally deinterlace for use in effects like dissolves etc. As far as I am aware cuts editing stays interlaced. If you shoot progressive you can export to interlace anyway and the source is there for file based playback without any of the artifacts of interlacing, the NLE will not have to use any of it's deinterlacing algorithms for effects so will stay a better quality throughout. By choice I would shoot progressive and export as needed.

Ron Evans

[Ron Evans]

I just realized that I should have said the value in shooting progressive is in editing and for playback from file. Since disc playback at the frame rates other than 24p will always be interlaced ( DVD or Bluray which will be interlaced anyway at 50i or 60i ) the quality one sees will be totally dependent on the player and TV. Flat panel TV's need a progressive signal and either get it from the player or deinterlace in the TV. A good modern upscaling DVD or Bluray player feeding an interpolating 120hz or 240hz TV will be as good as feeding a progressive input as I have demonstrated myself direct from camera.

Progressive input means less processing for video or extraction of stills.

I shoot multicam theatre using a NX5U ( only interlace), NX30U and CX700 I shoot progressive, XR500 interlace. Mixing them on the timeline is no problem.

Ron Evans

[Dave Blackhurst]

Let me toss in a couple pennies based on the original question....

#1 if you're shooting a scene with little or no motion, you'll likely see negligible difference if any...

#2, if you're shooting "stuff" in motion, you're more likely to see combing, a certain "blurred" quality and just a slightly less "sharp" image with interlaced. Because each frame of progressive footage is the entire "moment" (like a snapshot), if you freeze a frame, it will look (more?) like a picture, with motion frozen. The first time I paused a 60p clip, I was shocked by how good it looked... from a practical standpoint, I feel like 60p also just looks a bit sharper in playback - probably due to more "data" in the stream, if nothing else.

#3 it all becomes problematic when you start to talk about "final output" - I know all my "60P" cameras flash a warning that you can't put the footage onto any disks for playback (playback straight out of the camera and on computer looks GREAT)! I tend to render to 24p for final to reduce file sizes, get a little more "film look" (I guess, I still don't see a lot of difference!), and get a file that CAN burn to BR or BR format on DVD.


IMO, the higher data rates of progressive give you more to work with in post, so in theory as you "work downstream" towards the final output, you've got more to work with, and should get better final output.