Monday, December 14, 2009

Vidiocy OR::: 24fps (for pete's sake)

Watching one of my favorite films on a newfangled HD TV/ DVD setup the other week, I was (semi) mortified to notice that the "high-end" player was compensating for the Film-ness of the film, and was therefore doing some wonky things with the frame rate. I protested to my viewing companion that "the film doesn't actually look like this!" and, "This is weird, it looks like a British TV show." The film still worked, of course, and we had a decent enough time, but I remain(ed) bothered by the pomposity of this system changing the frame rate of something I knew very well should look another way. I started to gripe about frame rates: film vs. video, and the weirdness that occurs when trying to jump between the two, I had to stop short, however, of an explanation of how video actually worked, and/or why it was different.

Film makes sense. Film is alluringly and obviously physical. It is bound by all sorts of physical restrictions having to do with how much you can cram onto the strip, how fast you can pull the film through the projector or camera, and so on. It is one of those bewildering and elegant examples of arbitrary decisions in a design process like "QWERTY" or the width of train tracks, they're arbitrary decisions grounded in physical considerations.

Video was not as obvious to me. Again it is a physical system. Another analog format, but very different from Film. It converts and reads information as opposed to a direct transmission or capturing of a physical image (a cake vs a recipe). Film records and displays at a tight 24 frames per second. 24 images are displayed and shown in succession per second. Video (NTSC for us Americans) is either 30FPS (non-interlaced) or 60i (interlaced). Film is a non-interlaced format. Images are displayed one after the other in sequence. Interlaced video means that only half of the information of a "frame" (half of the scan lines) is rendered at a time. Alternate "fields" of scan lines are rendered in succession using half the bandwidth to display video image with much more fluid motion than Film. This type of motion we associate with TV and News Broadcasts (it is, after all, the standard for these formats, although the News is generally recorded at 50i).

As for video tapes, they are an analog format, same principles as audio tapes, pulled through and scanned diagonally by a play head reading an audio strip at the top of the tape, the interlace video information in the middle, and all sorts of stuff about tape speed and tracking along the bottom. The storage format is magnetic in principle, and information is encoded with electromagnets onto a layer of magnetic reactive coating on the tape (generally iron rust) that "remembers" its state.

There is all sorts of more information out there about display, encoding, interlacing, non-interlacing, converting, and whatnot, but this should suffice for now as a general run-down. In the case of this story, it sounds like the player was probably trying to pump it out at 60p (for progressive scan) but I'm still sore about it, so I'm not going to go into detail about that format. 24 Till Death!

DigiConform 24 vs 30

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