Wednesday, December 31, 2008

Five Mythconceptions About Video


24p will make your video look like film.

24p causes problems. Motion is not as smooth and if you don't pan carefully you'll get strobing. The film industry tries hard to minimize those problems. So be careful or it will make your video look worse, not better. Here's the main advantage of 24p: the p. Progressive frames compress better (meaning you'll get higher quality frames), and they display better on PC's, and non tube televisions (basically anything that has to deinterlace). And fewer frames per second usually means sharper frames. For example imagine I told you to pay attention, showed you 5 pieces of construction paper per second, and asked you to tell me what color they were in what order. Then I showed you 4 pieces of paper per second and asked the same thing. Which would be easier to remember and more accurate? Probably the sequence of 4 frames per second, right? That's basically what happens with 30 frames per second compared to 24. The video can have more detail per frame, at the expense of smoother motion.

Besides that, there are other reasons that make big Hollywood films look better than video from your camera. They have entire teams of people focusing on quality: lighting, color grading, visual effects. Film handles contrast better than video. They use way better equipment like lenses that cost more than my house, cameras that cost several times that, and state of the art computers and software. If you want better looking footage, invest in a camera with a bigger and better sensor, or a better lense (with a 35mm adapter for example), and software that can handle color accurately (After Effects, Color, Sony Vegas Pro). Do not expect 24p to be a magic bullet.

If you do wish to carefully make use of 24p and you have a camera that can shoot it, here are some tips: don't use a Saving Private Ryan high speed shutter. In other words there should be some motion blur. This makes motion more fluid and less like a strobe light. Either pan really fast or really slow. Or if you're doing a medium speed pan, put something in the foreground and follow it (like your actor). It distracts from the juddery motion in the background. Think the feather on Forest Gump. It wasn't done all for show. If you don't have a 24p camera, do not convert your framerate to 24p, unless you really really know what you're doing. It will be more trouble than it's worth.

AVI = uncompressed video with huge file sizes.

Lots of things can fit inside an AVI. It's just a container. You've heard of Divx, Xvid, or MP3's, right? Well each of those are codecs, which can be stored inside an AVI. DV from your camera is commonly captured to AVI, and while the file sizes can be large, it's not uncompressed. DV typically has a 5:1 compression ratio, meaning if it was uncompressed it would be five times larger! A codec is a coder/decoder (that's how it got its name), that translates your video into a file, then back into a video again. It's like abbreviations in your text messages. The words “be right back,” are coded to the letters “BRB” - saving space - then decoded back to words again so the reader can understand (hopefully).

So don't discount an AVI as being too large for your video. And don't assume because you converted to AVI the video is a perfect copy. In many cases you can lose quality when converting to AVI. It's the codec that counts.

If one video has a higher bitrate than the other, it must be better.

Quality, not quantityAll things being equal, this may be true. However, there are many ways to create a video and they are not all the same. Bitrate only tells you one thing: how much space a video takes each second. It does not tell you how wisely the video was compressed, or how outdated the technology used to make it was. To the right is an example. I encoded one video at 300kbps, then another with deliberately bad settings at 400kbps. Even though the second one has more data at its disposal, the poor settings chosen make it look worse. Remember – wise decisions will give you more quality in less file size. Educate yourself on compression, and how to make it more effective.

You need a Mac to do serious video work.

Macs are great. If you've got the money, they can save a lot of time and hassle. But there's plenty of competition on the PC side. Take Mac's Final Cut Pro with Color and Motion, and PC's Premiere Pro with After Effects, for example. In my opinion, Final Cut Pro wins over Premiere. But After Effects has Color and Motion beat. There are advantages and disadvantages to each.

But here's where Mac can't compete: price and compatibility. For $500 you can get a PC that can edit HD video and run Adobe Production Premium. No, it won't be the fastest computer ever created. But you can do it. With Mac you're looking at a minimum of about $1200 for iMac/MacBooks and $2700 for Mac Pro desktops. With the money saved by not buying a Mac, you could buy Vegas Pro and have money to spare. You can get Vegas Pro (disc only) from B&H, a trusted and reliable vendor, for $130. So an adequate PC with Sony Vegas Pro is $570 less than a Mac. Why not throw in an insane amount of ram and a 1TB hard drive with that extra dough?

I'm not anti-Mac. I'm just saying for the hobbyist with a limited budget, PC's are a great way to save. You may wait longer to render, but you'll still get the job done. In the above example I used a low end to average PC's price range to show the money that can be saved, but if you did put the $2,700 it would take to get a Mac Pro into a PC you would have a very fine machine. Which reminds me of one more thing about price: there are no cheap Macs. At least not new ones.

What was the other thing? Compatibility. There's plenty of software for Mac. But most likely you'll end up paying every time. Here are some reasons I love my PC: AviSynth, IMG Burn, Video for Windows (the framework that allows tons of codecs to work), WinDV, HDV Split. All great things you can get free of charge. Okay, you have to pay for Windows, but technically you can get the Video for Windows framework to work under Linux. I'm getting off topic. The point is many many programmers have made fantastic little apps, and many of them are for Windows. Go to Download.com and notice how many things are not made for Mac. This isn't to say Macs aren't right for some people. I'm just trying to appeal to the frugal buyer and let you know: you can do more with less. This leads me to the last myth.

Getting the best software and equipment will make me a good film maker.

This can be both a good and a bad thing. On one hand, you don't have to feel bad about having less. On the other hand, if you just spent a crapload of money on equipment and software you may end of saying “well what do I do now?” If having the latest cool stuff made you the next Steven Spielberg, having Micro$oft Word would make you a best selling author. You are what can make you good. People have done very well for themselves on YouTube with very unimpressive equipment (like WebCams). Not me however, I still suck. But find what you're good at and do it. Work hard with what you have and get more tools as you go. Maybe video isn't your thing. That's ok; just do what you do best. In fact, it may be in your best interest to start out with very cheap affordable stuff and find out making videos isn't for you. Would you rather spend a couple grand figuring that out? So be sure to use technology and cool toys as tools in your toolbox, not a robot to do all your thinking for you. Be smart and do what's right for your budget. And if you end up being a world famous juggler, maybe you can hire me to be your videographer.

5 comments:

CJ Bruce said...

Nice post! Very helpful stuff, I hear people ask these same questions all the time.

Jorge said...

I enjoyed reading this one. It would be great if you post in the future WHAT are those things you should take care when encoding a video (in order not mess it up).

I basically just take care of a couple of basic things like (assuming video is going to be shown in a progressive-scan device):

- do I need to deinterlace footage? or is it already progressive...
- do I need to crop black bars?
- am I'm going to down/upscale footage?
- do I need to take care of PAR when rescaling?
- do I need to boost the audio (volume wise)
- the order in which I applied the above operations

I use mencoder (along with its ffmpeg libraries) to encode most of my videos but I haven't really worked with the specifics of every codec...

All the best,
Jorge

NerdWithNoLife said...

Good points Jorge. I made a list of guides I'd like to do on improving video quality (and not messing it up) and I think there were 13 things on the list. Not sure if aspect ratio is on it but it will be now.

Tyler said...

"do I need to deinterlace footage? or is it already progressive..."

You may or may not need to, google DGIndex... its a program which create an index of a MPEG stream which can tell you information about each frame of the stream as well as what type of interlacing was used (even though its not always 100% correct)
Always check with your eyes for interlacing, if you see a 3 progressive and then 2 interlaced frame pattern, you can bet its telecined which is on a whole other topic ;)

Tyler said...

Sorry for the double comment but, if you need any assistance with deinterlacing video or whatnot, you can email me at corruptnova@gmail.com