Interlace vs. Progressive quality

[AJL14]

Hi guys. From Camera to EDIUS to Bluray, what's the quality difference "on the screen" in your opinion between shooting in 1080i and 1080p? All my shoots have been in 1080i, but new camera is also 1080p. General shooting - not just sports!
Mucho thanks,
Alan

[Dry Biscuit]

Hi guys. From Camera to EDIUS to Bluray, what's the quality difference "on the screen" in your opinion between shooting in 1080i and 1080p? All my shoots have been in 1080i, but new camera is also 1080p. General shooting - not just sports!
Mucho thanks,
Alan

Hi Alan,

I only EVER shoot in progressive (Anton will spit his beer out at this point :) but of course it's a matter of taste.

Don't forget you will lose circa 30% of vertical resolution by going the interlaced route due to the Kell factor (interlacing alone does not affect Kell but it must be low pass filtered and this does). This IS noticeable on larger displays - I use a calibrated 60" Kuro for reference and interlaced v progressive is very noticable.

[Zorro]

Alan, if we're talking 1080/60p here then keep in mind that you can't make a BD from a 1080/60p project in Edius because the resolution isn't part of the BD standard.

[THoff]

My preferred BD workflow is to shoot 30p and deliver 60i.

It is analogous to the early days of progressive digital shooting when the progressive image was encoded in a interlaced transport stream.

[Bassman]

Yes, Blu-ray is a key factor in this discussion. 1080p24 is the extent of 1080p for Blu-ray (US). Anything else will be converted 1080i (outside of 720p).

For the web it is a different story, but it is still a bit early for solid 1080p delivery imho. In my tests, shooting 1080i and exporting a 720p50 file compared to shooting 720p60 and outputting a 720p50 file resulted in a wash for computer viewing. (I use 720p50 to save 10 frames/sec on bandwidth).

So the choice is really about framerate first, then resolution. If you need 60p then your choice might be different than if you need 24p.

[AJL14]

Thanks guys. The only one factor that was not discussed was - on the Bluray 1080i picture, is there a difference between shooting 1080i and going to the Bluray, or shooting 1080p and then going to the 1080i Bluray. The final Bluray output is the one I'm interested in improving as much as possible. Mark - you mentioned the 30% loss in vertical resolution - but does that loss transfer over to the Bluray, or just get swallowed up again as we go to 1080i for the transfer?
Alan

[Ron Evans]

The choices for Bluray are interlaced or 24p or 1280x720P60. So if you shoot 1280x720P60 you can use that all the way through.

I still shoot interlace as all my stuff goes to SD DVD 60i anyway. I have compared video shot on my NX30 and CX700 in both interlace 60i and 60p directly over HDMI to my Sony 240Hz interpolating TV and I can't tell the difference because the TV interpolates things that are missing anyway !!! Even on my Panasonic plasma I really can't tell the difference both are 42". The big difference really comes when I want to take a still from the video. By choice I would shoot everything in 60P but only two of my camera I use for shoots can do that in 1080. ( the NX5U will shoot in 720P60 but the others can't. Easier to let the NX5U shoot 60i, XR500 60i and the CX700 and NX30 60p and I just edit on a 60i timeline.

When talking about the influence of Kell factor one has to look at where this may come into effect. Early sensors where close to or had less pixels than the displays but newer sensors have much higher pixel counts than the displays and the electronics decide what is to be recorded. The newer cameras are likely all progressive in image capture and only format the output for recording. Sensor pixel count for my NX30 , for instance, would be almost 3 times the display resolution. So even applying the Kell factor is still greater than the display resolution. Sony array also allows the electronics to identify off sensor detail in the interpolation. In these cameras the lens is really the limiting factor these days.


Ron Evans

[Bassman]

Alan, the best way is to shoot identical footage in both 1080i and 1080p, make a Blu-ray and judge with your own eyes. First hand experience is always the best.

"Normal" people will not notice, but "we" do. How important that is to you is subjective. If 1080p60 or 1080p30 was in the Blu-ray spec then it would be obvious, but they are not.

Another thing is that Edius will work better with an interlaced signal if you need to make a DVD from the HD source. You can downsample and encode high quality right from the timeline. For quick turnaround/lower pay jobs I would choose interlaced for this ease alone.

[AJL14]

Good stuff guys. Ron, your explanation is terrific, thanks. And Tim, I think I'll try to compare the i and p shoot and timelines to Bluray and see if I can tell the difference. My only problem now, is that my theater is all 4K - and the projector upscales everything to 4K, so I'm not sure the screen representation will be an accurate overview. The 4K upres does an amazing job out of the Oppo 103's 1080p signal. That said, your observation concerning timeline downres to DVD is a very valid one, for I have to do that all the time.

Have a great week - we're into 100F degrees plus in Los Angeles! (I know, I know - that's 38C for some of you!).
Alan

[Bassman]

I don't know if having a 4k theater would be considered a problem! :)

Maybe you can run out to Best Buy and watch your Blu-ray. Just go when the store is empty.

[SoundFreak_HD]

My only problem now, is that my theater is all 4K - and the projector upscales everything to 4K, so I'm not sure the screen representation will be an accurate overview.

Help is nearby, there are 'leaks' of a Sony handphone that shoots 4K with a 20MP camera to be released (Dec), soon you'll be 4K all the way :) LOL

[AJL14]

Can't wait - except for the fact that Sony is famous for saying December - when it will finally be delivered NEXT, next December!
Alan

[Ron Evans]

Alan, if you are intending feeding the 4k projector I would shoot 60p and feed the file from a player. You can always make a DVD or Bluray from the 60p source. I am not a fan of slow frame rates so 24p and 30p have the same issues with judder that I really dislike. Also for most viewers they see 3:2 cadence not 24p anyway as 60hz displays cannot show true 24p.

Ron Evans

[antonsvideo]

no cinema here would accept 60p or 50p

it has to be 24p

[Ron Evans]

Yes I forgot they are stuck in the old ways. Such a beautiful picture destroyed by judder of an economic decision years ago.

Ron Evans