60i vs 30p vs 24p

[Dave Rosky]

Originally Posted by Aaron Courtney

Third, exactly how did you encode a 30P file out of your NLE?

Aaron, I think there are many encoders that can generate 30P files. For example x264 can generate progressive 30P AVC files. I believe there are MPEG2 encoders that can do it as well.

The real problem is the delivery, which you do mention. It will be interesting to see what you hear from the chip set vendors, but it seems for now the only way of delivering 30P to a TV without first going through 30PsF is to use a PC (i.e., have the PC use the TV as a 60Hz monitor).

[Aaron Courtney]

Originally Posted by Bob Kittleson

Aaron, I mean no disrespect but you haven't provided any sources to back up your assertion that fixed pixel displays produce 30fps output from 60i input streams. I can't prove you incorrect either, but intuitively what you said doesn't seem to add up. How can the following points be explained?

http://www.hqv.com/technology/index1...TOKEN=16476801

This is a good read on the subject of de-interlacing by HQV, one of the leading vendors of video processing technology. As you say, you don't believe half of the vert rez is missing from interlaced video while displayed on your progressive set, which means perhaps this blurb is a bit dated, since no one seems to be using non-motion adaptive de-interlacing any longer in these displays or BD players.

- If displays process 60i as you describe, then half of the motion resolution would just be thrown away for video content that was actually recorded in 60i. I don't know about anyone else, but when I replaced my CRT display with a fixed pixel display, I did not notice any loss of motion smoothness. I would think that a reduction by half would be noticeable.

On the contrary. Motion resolution compared to what? Interlaced CRTs? I don't like the term applied to fixed pixel displays because you have ONE resolution - the native rez of the screen. And that's all you've got. Proper de-interlacing attempts to minimize motion artifacts that are created when the two fields are recombined to display as a full frame on a progressive display, yielding back the original 30 fps. Again, read the HQV blurb...

- The latest camcorders continue to record in 60i as their default mode, even if capable of 30p recording. Canon does not market 30p as being equivalent or better than 60i when played back on a "good" display. We know that recording in 30p eliminates deinterlacing artifacts, so why would anyone want to record in 60i unless it provided some benefit in terms of motion resolution? You could argue that this is because there are so many displays that don't handle 30p 2:2 properly, but still I would think that if ANY displays existed on which 30p was flat out better than 60i, then Canon would market that fact.

30P is flat out better in all things except compatibility when compared to 60i and viewing on progressive displays. This is factual and not even debatable. Due to the compatibility issues that I and many other professional reviewers have raised, manufacturers are clearly sticking with outdated technology rooted in NTSC. Seriously, how can anyone argue that capturing half of a frame and then capturing the second half of the same image 1/60 sec later is better than simply capturing the entire frame all at the same time? If you capture progressively, you don't have to deal with this de-interlacing mess and trying to minimize the problems you get when recombining the fields. It all just goes away, LOL.

- Our buddy Ken Ross is an experienced video enthusiast who has tested both raw 30p and 60i video footage on a Kuro, which is one of the best displays available. He has clearly said that 60i video looks smoother to him.

I would bet money that his Kuro cannot properly de-interlace 30P in 60i video. And by properly, I mean (1) detect lack of interframe movement within the two fields comprising that frame and necessarily employ a weave de-interlace process, and (2) frame double the original 30 fps to match 60 cycles per sec of the display.

- The article below notes that some crummy displays simply interpolate each individual field to form a full frame. This results in poor spatial resolution, but the full motion resolution of the 60i input stream is preserved. If crummy displays can retain full motion resolution, I find it hard to believe that good displays would not do likewise. I have not seen any articles that say motion resolution has to be sacrificed to get full spatial resolution.
http://www.hometheatermag.com/hookmeup/1107hook2/

IMO, this occurs when the video processor "gives up" on properly de-interlacing interlaced fields and is certainly NOT desireable. If that is "success" in your book, then you may as well stick with 720/60P and get real HD video.

- This is pure speculation on my part, but if a good display can properly deinterlace field pairs within a frame, wouldn't it be possible to likewise deinterlace fields from adjacent frames?
For example:
Input frame 1 field A + input frame 1 field B = Output frame 1
Input frame 1 field B + input frame 2 field A = Output frame 2
Input frame 2 field A + input frame 2 field B = Output frame 3
Input frame 2 field B + input frame 3 field A = Output frame 4
...
This approach would in theory yield 60 unique output frames per sec on the display. It doesn't seem fundamentally different or more difficult than only deinterlacing intra-frame field pairs, other than requiring more processing power because more deinterlacing is being done.

Again, then you're technically not trying to combine fields comprising the original frame as captured by the video camera. You're trying to fabricate a frame that did not exist ala 3:2 pulldown (the problems of which have been identified for years and thus the whole reason for removing pulldown while editing 24P video, rendering out to true 24P BD, and then buying electronics that will pass ONLY 24 fps to the display at which point the display then frame doubles, triples, quadruples, or quintuples that original video or film frame in order to provide a better viewing experience.

[Aaron Courtney]

Originally Posted by Dave Rosky

Aaron, I think there are many encoders that can generate 30P files. For example x264 can generate progressive 30P AVC files. I believe there are MPEG2 encoders that can do it as well.

I'm using Vegas Pro and have not been able to figure out how to do it without rendering to a 1080/60i template. But I'm sure you're right, although I'm not sure of their relevance for HD distribution since all we have at this point is BD.

[Ken Ross]

Originally Posted by Aaron Courtney

This is a good read on the subject of de-interlacing by HQV, one of the leading vendors of video processing technology. As you say, you don't believe half of the vert rez is missing from interlaced video while displayed on your progressive set, which means perhaps this blurb is a bit dated, since no one seems to be using non-motion adaptive de-interlacing any longer in these displays or BD players.

Please, let's put this to rest, half of the resolution is NOT thrown out. Gary Merson's testing on many fixed pixel displays proved that beyond a shadow of a doubt. My eyes prove that beyond a shadow of a doubt. His testing on Pioneer plasmas showed them to deinterlace perfectly (as well as other brands) with none of the resolution thrown out. Let's understand this is 2008 and the processing is a whole lot different than it was just a few years ago. An article written almost a year ago is just about hopelessly out of date by now.

As to your preference for 30p, so be it, that's why we have choices. For me, 60i provides significantly more of the 'you are there' look. I could care less about trying to imitate the look of film...no consumer video camera can do it even near-convincingly. If I want the look of film, I'll buy a film camera. Videocameras do best what they were designed to do, shoot video that looks like video.

Now, if you believe that 30p looks better than anything else on a CRT, so be it. But to me watching a 32" display is not exactly cinematic. It strikes me as very very ironic that the same people who are obviously striving for a cinematic 'look' can only achieve that 'look' on a relatively tiny screen. Not exactly cinematic now is it? But hey, that's just MO. :)

[Bob Kittleson]

To be more accurate in my last post, I should have used the term "termporal resolution" rather than "motion resolution".

I'll let this rest for now, but in my mind there is still a lot of uncertainty.

For those with camcorders which only record in 1080i, this whole discussion is academic. Shoot in 1080i and just be happy. :)

For those with camcorders that also record in 30p, it seems prudent to follow Ken's example and do A/B comparisons of 60i and 30p with your camcorder and your display and see what looks better to you. That's what I plan to do.

Thanks guys.

[Aaron Courtney]

who said anything about film? LOL! This discussion has nothing to do with film "look". It has to do with delivery of progressively shot and interlaced video to be displayed on progressive televisions. Also, I would not try to feed my interlaced CRT a 30P stream because it's an interlaced set, so 60i works best. The bottom line is whether one chooses 60i or 30P, you're only getting 30 real frames/sec when the stream is pushed out to a progressive display.

[Ron Evans]

I am with Ken. I don't want the "film" look I want nice smooth video to give me the impression "I am there looking through a window". Low frame rates cannot give this because they are unable to take enough frames to capture the motion. Its why 24p and 30p judder something I detest. I do not know how my Panasonic plasma deinterlaces but I can tell you that played from my camera it looks acceptable ( still not as smooth as a CRT) however transfered to a disc and played from the PS3 ( which upscales to 1080p30) it is not as good. I am beginning to think that I will not like Bluray if everything is 30p !!!! In my mind there is ample information in a high definition interlace stream to create a 60p stream rather than 30p since most of the image is not moving unless there is panning or zooming something the higher capture rate of interlace provides as an advantage over lower rate progressives. There are now lots of DVD players that will convert SD DVD's for display at 1080p. To me that's a much bigger task than interpolating the odd or even lines with motion detection. It would be nice to know if there are any progressives displays that do deinterlace to 60p not 30 with repeat frames.

Ron Evans

[Aaron Courtney]

Actually, Ron, since most of BD releases are from Hollywood, the majority of BD discs are 24P, LOL!

[Ken Ross]

And those BR discs originate on FILM and not video. There is a big difference in how video and film translate on BR. Some BR players do better than others in this respect, but yes, you will get buttery smooth motion with 24p film-based BR discs on fixed pixel displays. Getting that same smooth motion from videocameraas recording 24p is another matter.

[Ron Evans]

Just found this which may be of interest to this thread.
http://digitalcontentproducer.com/hd...cing_2_011907/
I am well aware that Hollywood is likely film based at 24p my particular interest is in concerts/theatre which are more likely to have been recorded by video cameras and the concern I have is how these have been recorded. I would prefer higher frame rates because of the motion, especially on the near stage cameras or for dance. 24p or 30p just doesn't cut it for these situations. I have little interest in Hollywood films I actually do not own any, in any format, even tape.
Ron Evans

[Aaron Courtney]

Yeah, that does shed some more light on this subject, but it also shows its age since everyone has moved on to native 24P support at the display. The article is also missing the topic of de-interlacing 30P in 60i. Steve is a member here, so I'm surprised he hasn't jumped into this discussion.

Ken, perhaps you can explain to me how 24 fps shot with a film camera is different than 24 fps shot with say a Panny HVX200 (after removing pulldown frames if shooting 1080P) assuming identical shutter speeds. I can dump both streams on a 24P timeline in Vegas Pro, edit, and render out to a 24P BD. How is it possible for the BD player to realize one part is derived from video while the other part is derived from film?

[Graham Hickling]

> QUOTE: Seriously, how can anyone argue that capturing half of a frame and then capturing the second half of the same image 1/60 sec later is better than simply capturing the entire frame all at the same time?

If its footage with motion, I'd rather have some visual info every 1/60th of a second, rather than every 30th, thanks. I decided that after owning a 30p JVC HD1 for 6 months a while back .. replaced it with a 60i Sony.

Obviously I'd prefer 60p (and in fact I often use software to deinterlace 1080i60 to 720p60) but 60i will do for now.

[Dave Rosky]

Originally Posted by Aaron Courtney

Yeah, that does shed some more light on this subject, but it also shows its age since everyone has moved on to native 24P support at the display. The article is also missing the topic of de-interlacing 30P in 60i. Steve is a member here, so I'm surprised he hasn't jumped into this discussion.

Maybe he doesn't frequent all of the threads in the forum, I know I don't - there are so many of them. But judging from the article, I agree he might be a good voice to have chime in here.

Ken, perhaps you can explain to me how 24 fps shot with a film camera is different than 24 fps shot with say a Panny HVX200 (after removing pulldown frames if shooting 1080P) assuming identical shutter speeds. I can dump both streams on a 24P timeline in Vegas Pro, edit, and render out to a 24P BD. How is it possible for the BD player to realize one part is derived from video while the other part is derived from film?

I think film looks smoother partially because of the art and experience behind it. 24 fps juddering is most noticeable during pans and zooms at certain speeds, so professional filmmakers try to avoid pans and zooms in certain speed ranges that tend to look bad. Every once in a while it can't be avoided and you do occasionally see a juddery pan in a film, but it seems pretty rare. Since a certain amount of motion blur helps, I imagine they also try to keep the shutter speeds down within a certain range by using slower film or neutral density filters when shooting outdoors (just guessing here).

[Ken Ross]

Originally Posted by Aaron Courtney

Ken, perhaps you can explain to me how 24 fps shot with a film camera is different than 24 fps shot with say a Panny HVX200 (after removing pulldown frames if shooting 1080P) assuming identical shutter speeds. I can dump both streams on a 24P timeline in Vegas Pro, edit, and render out to a 24P BD. How is it possible for the BD player to realize one part is derived from video while the other part is derived from film?

Aaron, therein lies the problem with video-based HD on BR. Some players are quicker to recognize the flags (assuming they're properly implemented on the DVD...many are not) and thus more properly reproduce the source as intended. Other players pick up on the sequences late or not at all, creating motion or resolution issues. I don't profess to be an expert in this, but I've seen the end results in some of the players I've had.

The bottom line in my mind is that the vast majority of the displays today are fixed pixel. So issues or not, that's the display technology of our day. If for whatever reason 24p or 30p look worse relative to motion handling, why would I not want to go to 60i if I find this motion handling disturbing? Why should I have to jump through hoops to obtain the buttery smooth motion of 60i by simply rolling the footage? To top it off, I've yet to see any 24p or 30p video that remotely resembles the 'film look'. But again, that's just me.

[Aaron Courtney]

Originally Posted by Graham Hickling

If its footage with motion, I'd rather have some visual info every 1/60th of a second, rather than every 30th, thanks. I decided that after owning a 30p JVC HD1 for 6 months a while back .. replaced it with a 60i Sony.

What's the point if the de-interlacer is simply going to merge those two fields into a complete frame for display on a progressive television? What's more, the motion that you just spoke of that occurred between those two 60i fields must be blurred by the video processor in order to prevent our eyes from detecting those hard edges when those two fields are weaved together. 60i is only yielding 30 real fps, as captured by the camcorder, any way you cut it on a progressive display.

The reason you did not like your 30P JVC is because 30P was being delivered via 60i and your display chain did not properly de-interlace 30P in 60i.

Ken, yeah, you're right. 60i is and will continue to be universally supported. It's unfortunate that the consumer electronics industry is having these growing pains because it limits our choices with video work. Hopefully, things will improve in the next year or two.