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10. The Joy of Interlacing
3 years ago
Interlacing is not evil. In fact, it's a brilliant solution to some really thorny technological problems. This segment explains exactly how interlacing works, why it's important, when you want to use it and how to get rid of it when you don't.
* 2009 Silver Telly Award winner (highest honor)
* Vimeo Staff Pick (even bigger honor!)
videopia.org
* 2009 Silver Telly Award winner (highest honor)
* Vimeo Staff Pick (even bigger honor!)
videopia.org
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Thanks for sharing!
But seriously: Yea, I'm passionate about this stuff and am happy to give a little back to the Vimeo community you all have given us.
I just wrote this on the the DJ forum but I thought it was worth repeating here:
"If they (Digital Juice) wait too long to hire Eric Franks back for the TechKnow show once the economy picks up again, they might lose him because his audience is moving over to his new Videopia site.
Just a guess but once Eric figures how to make $ off his new site, he won't need to go back to DJTV. "
Actually, I wouldn't recommend YouTube at all: I work at 1280x720 30p for Vimeo at the project level. And then render to that too. (Actually, I did this one at 29.97, but drop frame timecode is a whole other topic that can be summarize: no frames were actually lost when we counted to 29.97. Long story involving RCA engineers 60Hz AC power, etc. etc.)
Btw love these videos! very helpfull.
Why 30p when Vimeo is going to convert it to 24p (according to their FAQs)?
Many thanks
"If it looks good, it is good."
I guess it was convenient to say that to get good quality progressive video u need not good cameras, but very good and not expansive, but extra-expansive cameras. THis is what bugged me the most i guess. Man i wish i could afford a good progressive camera.
Another thing it bugged me is tat u forgot to mention also how genious was the fact that 60 frames per secound is not only important to handle the tv flickering, but also to handle convertions from pal.
Ow i also got bugged by the fact that seems it was ignored that, when u have progressive video at 30 fps on digital displays it won't flicker, and also a tv can interpret 30 fps progressive as interlace, so it won't flicker.
I guess u missed the most important point on the topic: the amount of reality in motion resolution, wich is -ussually- less resolution for movies, fiction, art and more resolution to live events like news, interviews, tv shows, etc.
But i have to agree that video is very helpfull when explaining to someone why 30 fps interlace are for real 60 fps.
And that's the current frustration: Most quality cameras are still interlace, but most distribution is progressive. I think the speed of the shift to progressive distribution caught camcorder manufacturers by surprise. It caught me by surprise! I mean, we knew it was coming, but who knew it would be THIS FAST?!
I've been kinda waiting thou for the shifty on camcorders having progressive... since internet and video distribution ended making (as even u said) interlace as a evil.
Anyways, thanks for u podcasting it's intersting, not much new info for me but i've pointed to a few people, since it's more explicative then I am.
We made no progress really since we're still bound to 25p/30p and we do need 50/60p for fluid motion (well for home video's or sport recordings).
i also loved the explination of why it was made up, i always wanted to knew why exactly it was created but was always lazy to research.
well..i know this is not concerns exactely what was talked bout in the video, but ...i see some serious ppl here so i have to ask...
im in a "Pal country", so i have to shoot at 25p.
It is progressive, hence, i expect to have the results im used to see.
However, when i compare my footage [shot using DVX100] to the same camera, though an NTSC one [shot at 24p]-i can definitly feel the difference!
the movement, and feel of the picture is Much better!
then,could it really be? the lame difference of 1 frame, to be so critical, in the final result?
Pal's resulition is better...but the 'filmy' look is just crap :\
To me, saying that "later the remaining lines are filled, creating a frame" does not seem technically correct. There are no frames in interlaced TV, just fields. Digital interlaced TV logically group fields into frames but still, fields are shown independently. The video implies that after the first field of a frame is shown, image stays on the screen, waiting for the next field to complete the full frame, while in reality fields are drawn in sequence, so full frame is never created. Your example with an apple is somewhat artificial, because no one ever will see an image like this on a regular TV, only in an NLE or in progressive video that was not deinterlaced properly.
Saying about 60 fields creating 30 flicker-free frames is confusing. Interlaced frames is imaginary substance. Instead, fields are shown independently with 60Hz scan rate (again, I am talking about normal TVs, not computers), which is why video has this truer-than-life look. If fields were combined into 30 frames, video would look more movie-like, but this does not happen.
Statement about 19Mbps being not enough for 1080p seems obsolete. Maybe it was right 10-15 years ago for older codecs and for ideal video quality. These days we have HD programs that are broadcast with 15, 12 and even 10 Mbps and brodcasters have the nerve calling it HD. On the other hand, 1080p being progressive is compressed better than interlaced, I came across 1.2 coefficient several times from reputable sources, this is how much more bandwidth 1080p requires compared to 1080i. 15Mbps * 1.2 = 18Mbps, which means that in fact 1080p is possible right now with acceptable quality. And don't forget AVC and VC1, which deliver better quality with the same or lower bandwidth than required for MPEG-2. Some estimations claim up to 2x reduction in bandwidth compared to MPEG-2, if encoding is done with high-quality equipment (this does not seem to hold true for current generation of consumer AVCHD camcorders). Satellite TV and European broadcasters use AVC instead of MPEG-2 to either increase quality or to reduce bandwidth of their HD productions. FCC made a mistake when it required that all consumer HDTVs should have a receiver inside them, effectively putting an end to consumer "HD-ready" panels without receivers. You can still buy such a panel for industrial or office use, but not as consumer equipment anymore. With recieverless panels all a user would have to do is replacing MPEG-2 box with AVC box. If American TV industry switches to AVC now after so many TVs with recievers have been sold, this would cause huge outcry, so we are stuck with MPEG-2 and with 1080i for quite a long time. The good thing is that TV manufacturers finally managed to decode 2-3 cadence, so at least we can watch 24p movies and prime time shows in full 1080p.
Buttttt, in this case I'm going to disagree (politely!): What I said was accurate for explaining interlacing to a lay audience in four minutes and thirty seconds. What you've added would have meant another 2 minutes (at least) and, in the interest of time (and interest!), I chose not to go there. Yes, we could have spent time on 60Hz AC and 29.97 drop frame (which really doesn't drop any frames and is actually a separate technical issue from interlacing anyhow). Don't blame me for inaccuracies in the demo video: that's from RCA, the inventors of the technology - and I agree with their choice of leaving the first field up anyhow: makes the concept easier to understand. While I agree with you that "30 flicker-free frames" is a minor gloss, it is alliterative and fun to say (many takes on that one!). No, I disagree about the "more movie like" comment, but that's a whole other segment and debate. Yes, of course you can cram anything into 19Mbps if you want to, but my point was that THAT is the reason 1080i is the broadcast standard settled on by the networks and NOT 1080p (although I bet we see a switch there as pressure from satellite/cable operators start to offer 1080p - besides the fact that being limited by "broadcast" bandwidth now seems silly years later, when it only effects 15% of households AND that 15% is the LEAST likely to have a 1080p monitor). No, I hadn't heard the 1.2x more bandwidth thing - that sounds really interesting. No, I didn't forget AVC, et al - just outside of the realm of a sub-5 minute discussion of Interlacing.
(In short: thanks for your comments and thanks for keeping me on my toes!)
And I am going to stay well clear of using Mac, Vista, Premiere, FCP whatev... there are plenty of people that teach that stuff on the Internets. I needed screen grabs that showed things like "Field Order" and "Deinterlacing Methods" - but basically I just wanted to help people identify IF they have an interlacing problem and point them in the right direction IF they do (e.g., set your project to Progressive!).
I really appreciate you're taking the time to explain these things. this is so much better than browsing net for hours and reading tons of boring stuff.
just watched all your previous videos as well. the one about DIY steadycam was particularly inspiring.
keep those videos coming, man! ;)
I love it!
Very useful
And, yea, I try to add a little spice to what would otherwise be a boring topic (just wait until I nail the "Film Look" or put on video my segment on why Blu-ray is already a dead technology - then we'll have some fun), so if I pique a little criticism I'm pretty happy, but, seriously "half truths and misstatements"? Really? I think I covered the ground in 4.5 minutes pretty well.
When I watch 30p (contained within 60p) and 24p on my progressive LCD TV there is no flicker.
1:40 "and pretty clever for the 21 Century too were we still use interlacing to reduce the data rate and bandwidth of the highest resolution HD television standard 1080i"
1080i is not necessarily the highest resolution. This depends upon what type of resolution your looking for.
1:54 "most high quality camcorders shoot interlaced video which would be really convenient for shooting traditional television which is all still mostly interlaced"
First none of what is on screen at this time would be used to shoot traditional television. Second a lot of TV is shot and delivered in progressive. Third see second.
2:24 "when video is automatically and necessarily deinterlaced"
Of of course nether is true. If it is interlaced some one (or program) has to deinterlace it and if it is shot progressive it doesn't need to be deinterlaced.
Not trying bust your tubes on this, just thought people should know.
1:01 yea, but 30p ANYTHING would flicker. 30p movie film... anything. It's just too slow. Which is why movie theaters do the double shutter thing. LCD panels don't turn off in between and have a faster refresh rate (OK, I made that up - I have no idea, but it's probably true. 60Hz would be my guess.)
1:40 ah, but 1080i was the highest resolution the networks settled on, due strictly to bandwidth limitations. Otherwise, how do YOU explain 1080i? Was it a bunch of idiots sitting in a room throwing darts?
1:54 I agree with you on this one, but, once again: Why are all those cameras interlaced? A bunch of idiots at Sony and Panasonic? It's because when those cameras were designed and engineered, they were spec'd for interlaced distribution (e.g., DVD-Video). And, as of today MOST television is still interlaced.
2:24 If it's on the Internet, it's been deinterlaced. I've never seen a media player that ran fielded. I know in the header for the files you can render interlaced, but that's not how it comes out on YouTube, Vimeo, or any other destination I've ever seen.
And sincerely: thanks for challenging the details and this conversation. It's clear you know what you are talking about, so I appreciate the picking of nits of all sorts - it keeps me sharp and accurate.
Rich
edit: OK, I dunno if you ever got the mail, but I saw your registration and verified it. I'm a better writer than I am a web admin, but I do what I can.
However.. Even progressive at 15 fps, for me looks much nicer than interlaced scanning, here a super 8 example..
vimeo.com/1045388
But thanks for the explanation..
Just kidding: I know I ask for it with semi-provocative titles and use a bit of rhetoric to spice things up, but yea I do stand by the statement "Interlacing is not evil."
And stating that the DVX100 made history with cinema mode is overstating things just a little bit. I know Panasonic marketing wants everyone to think that, but it's just a really nice camera in its class. Not magic. Boy, I'm really gonna have to put on my flak jacket when I slam 24p as a marketing gimmick.
But thanks for the comment! And your eyes do not lie: whatever texture you like in whatever mode you wanna shoot - that's the right one! Don't ever let a nerdy tech guy like myself tell you otherwise (and I promise I never will).
Videopia: Y´r right.. really the title provoked me as a "progressive" lover.. I also had a lot of problems in the past when editing dv/pal, I really would like to see the interlaced scaling dissapearing of the world..
call me "progressive" guy ..
;-)
(Hmmm, unless the camera shoots 60p but also shoots 120i - that would be cool.)
Again, right on Dustin and thanks for the comment!
So nice to see someone using Vegas who knows a lot about what they are doing on the technical level. A lot of the Vegas help resources online are full of amateurs.
Do you guys think or know if it will be an ackward transition? And also do they make a specific Vegas for HD and/or 64 bit systems? Thanks!
-Sean
1. Being informative.
2. Being entertaining.
3. Keeping it short.
Great job!
P.S. I think C.S. Lewis rocks! :-)
Also it is far easier to convert progressive scan pictures to interlaced than convert interlaced to progressive (where the results are rubbish)
Internet technology and speeds are perfectly capable of handling 1080p, so is satellite broadcasting. Terrestial broadcasting is holding back progress and should be consigned to history
And, yea, the Internet and broadband distribution changes all of this, but that is a very very recent development. AND we producers are gonna have to deal with interlacing until next gen cameras come out - thus my segment.
My point is about the future of video which is being held back by (interlaced) television.I had to wait 8 months to buy a decent camcorder until the Canon HV20 came along (The only true high def progressive scan consumer camcorder I know of).I live in the UK so its 25fps is ideal (although its a big nuisance that it's output is 50i), I know US versions are a pain because the 25fps has to be messed up to output as 60i due to the stupid standards imposed by the AVCHD standards.My main point is that there will never be any really good camcorders (professional or amateur)until interlacing is totally ditched, and a single worldwide video standard is adopted. Broadcast television is dead and needs to be buried asap.
However, I doubt there will ever be a single worldwide video standard:
videopia.org/content/view/94/229/
Of course, the death of broadcast television and the rise of Internet video changes all that: Who even needs standards anymore at all beyond Flash or QuickTime or whatev? Still, us rich folks with our fancy computers and $100/mo broadband don't represent the rest of the planet, but it'd still be nice to see a new class of quality progressive scan cameras come out.
If im shooting on a canon HV30 using 30p.
Should i not de interlace? because its shooting in progressive already? Or should i?
thanks for the reply : )
But, ultimately, you can just look at the video: if it looks good, it is good. If you can't see any interlacing artifacts on fast moving object with the frame frozen and examined closely, I wouldn't think another thought about interlacing!
It wont matter as much as when you shoot in 24p mode
You're not shooting 30p on the HV30 per se. If I recall correctly, it's 30PF. Canon wraps 30p in a 60i wrapper which HDV tape has to be. Same goes for 24PF on the HV30.
However, the primary reason the video looks so good is the lighting during production. Garbage in, garbage out and you can't polish a turd and all that, but it's true. Now, it also helps that a big, unmoving, uncomplicated background and low-motion subject makes compression easier/better, but starting with the absolute best quality scene to shoot is always Step Number One.
Which might raise the question: How did I show the interlacing artifacts in the ball demo? While the actual interlacing you see is real, it was rendered at a lower resolution to exaggerate the effect and then composited into the 720p project you see here.
Thanks for the note and the question!
This is exactly why you need to do your next video on basic lighting. For an art form that uses light to create images, it amazes me how little most people know about basic lighting.