Compression is an art, as I have learned from my many interviews with people and companies. When you view movie trailers from the Apple site on your computer, they look beautiful and perfect, with high quality imagery and sound. But creating those trailers involves a lot more than meets the eye.

Initially, I spoke with Doug Warner at Apple, who work compresses movie trailers for the web. He directed me to the Media Relations department, who put me in touch with Rhonda Stratton, the QuickTime Product Line Manager. When I asked her what was required for movie trailer compression, she said: “99% of movie trailers originate on film, so there are specific considerations that you need to take into account that are not an issue with video. If it originates on film, it comes to us after a 3-2 pulldown has been done, which is what they do when they convert film from 24 frames per second (fps)."

"As a basic explanation, sometimes 3 or 2 frames are taken, because you’re going from a 24 fps film to normal NTSC video, which is 29.97 fps. A conversion has to be made and it is still somewhat of an art. You can do a completely mechanical 3-2 pulldown, but every once in awhile someone will be able to catch it, whereas if you have an artist look at it, they cam pull out frames at the right times and make it smoother."

"What’s great about the web and QuickTime is that you can use any frame rate. You don’t have to do 29.97, which is necessary for television. On the web, you can use compression tools and go back to the original film as intended. Typically, when you want to remove 3-2 pulldown artifacts, you would use an application such as Adobe After Effects or Discreet Media Cleaner."

"We try to get the very best experience that the director wanted for the viewers, so if we can, we’ll go back to 24 fps. If someone’s going to watch this trailer on television, we have to do 29.97, but on the web we’ll do 24 fps. From a compression standpoint, a lower frame rate is better from a data perspective on the web."

Nathan: Right. It doesn’t clog the bandwidth. Speaking of that, I heard about a process called Progressive Download. What does that mean?

Rhonda: "That’s definitely a consideration that you have to make when you’re deciding on delivery. Perhaps I started this in the wrong order. To answer your number one question, the things you have to think about are: who is your target audience? What is the bandwidth that you’re going to be delivering? What are the connection speeds that people are going to have? Here, we've made those decisions. We always deliver our trailers in 3 or 4 bandwidths and we don’t usually vary on that, based on our past experience. We usually do 300, 100, 56 Kbps, or on the higher end, going up to 500 Kbps or 1 Megabit, into the DSL or broadband range."

"With Progressive Download, the tradeoff that you’re allowed is real-time streaming, which is a bit of a misnomer here. We’ve talked about streaming, which starts up and streams to your desk in real-time. The other option is called Progressive Download, sometimes known as Fast Start. This downloads the video, instead of using real-time transport. QuickTime has a special feature that will start playing when it thinks it’s got enough downloaded. If you have a really fast connection, it appears to be streaming."

"The technology behind the scenes is a little different, but because of the design, any bandwidth person can get that video. With a real-time stream, for example, 300 kilobits could be necessary and unless you have that or faster, you can’t watch it. If you’ve ever tried to watch something that’s targeted for 300 kilobits and you’re on a 100 kilobit line, you’ll see a picture, then nothing. It will hiccup and burp and the quality is terrible."

"With Progressive Download, you could say: ‘I want the biggest, fattest and most gorgeous picture’ and because it’s being downloaded before it starts playing, it takes a bit longer, but you’ll get to see the biggest, fattest, most gorgeous picture that you’ve chosen.’ For movie trailers, the person who is making the decision, can say: ‘I want my audience to see high quality. I don’t want them to have any hiccups, spurts, etc.’ And people will see that because it’s being downloaded to their machine. The only time they wouldn’t is if they downloaded it to a really slow machine that couldn’t play it back."