|
I wanted to give you a little bit of information about frame rates so that you understand the concept behind the several types that there are. When scoring there are 2 important time formats to understand. The first is Real Time. Real Time is simply the time in hours, minutes, seconds and hundredths of seconds. As you're probably aware, film is made up of individual still frames passing over the screen at a rate too quick for the human eye to see individually. Thus, it gives the illusion of motion. Frames rates determins how many frames pass over the screen within 1 second of time. When scoring film there are 5 frame rates you may come across: 24 Frames Per Second (fps), 25fps, 29.97 fps Drop, 29.97 fps Non-Drop, and 30.
24 & 25 fps
These two frame rates are the easiest to deal with. They simply mean there are 24 or 25 frames which pass across the screen in a second. 24 Frames is the standard frame rate for cinematic (film) and now HD. 25 fps is the standard introduced by the Europeans in the 1960s as an improvement to the NTSC standards developed by the Americans in the 1940s. If you get given a film for scoring in either of these formats - its easy! The time will pass by in seconds and instead of hundredths of seconds you will have divisions of either 24 or 25. (N.B. Don't forget that, just like MIDI, frames start counting at '0' rather than at 1, so the last frame of 25fps timecode will actually be numbered 24 and teh next frame will be 00.) So, in 25fps, each frame is equal to 4/100ths of a second, meaning a time code that reads: 02:01:27:04 actually means 2 hours (or reel 2 if working in reels) 1 minute, 27 seconds and 16/100ths of a second in real time.
29.97 Drop / Non Drop and 30 fps
This is where it gets a little complicated though I will try my best to explain it as simply as I can. In reality it's not essential information as long as you know to set your synch machines in the right frame setting. But here's a brief look at the theory behind the madness:
When people talke of NTSC (the American standard for television) they think of 30 frames per second. However, the reality is that it plays 29.97fps. It all has to do with electricity, which operates at 60Hz. The NTSC standard was introduced to accommodate the release of the color television in the 1950s but the TVs operate at 59.94 Hz. If you double 29.97 you get 59.94, and that means that the frequencey allows for 2 fields per video frame.
Do not be fooled by thinking that Drop-Frame means that you actually drop a frame of film. It's just a means of counting and the standard delivery to TV networks for time accurate broadcasts. If you played a piece of film that had been edited twice, once in Drop and the same piece in Non-Drop the real time length of the film would be exactly the same. However, as drop and non drop are simply two different ways of counting their time code woudl mean different real times. Drop frame actually drops numbers rather than frames. It counts each NTSC frame and when that .03 of a second catches up to 1 whole frame it jumps forward a number, or you coudl say it 'drops' a number. Drop-frame is actually the accurate way of counting time.
Non-drop does not make allowance for the fact that the frame rate is actually 29.97 and counts it as if it was exactly 30 frames per second making non-drop frame lengths shorter than drop frame. The best way to show the significance is through this simple calculation:
When counting in non-drop, it counts 3000 frames for 100seconds, but in reality its 2997 frames for 100 seconds, meaning that it adds 3 frames in counting length to every 100 seconds. Although the real time would be the same, the counting time would make Non-Drop be 108 frames further ahead every hour.
There are some advantages for film makers when choosing to go non-drop, but those advantages don't affect us as composers. As long as you know to ask your editors whether the frame rate is drop or non drop and set your internal frame rate to match, your sequencer will always synch with the time code shown on the picture.
|
|
|
