Temporal Resolution

In my very first post to this blog I complained about the limitations of video frame rates (temporal resolution). I was reading more on the products offered by Geometric Informatics and it seems their GeoVideo Real-Time Motion Capture Camera runs at a frame rate that begins to make things interesting on the road towards what I will call Granular Motion Synthesis.

Granular Synthesis in reference to video has been inaccurately co-opted for some years by Kurt Hentschlaeger and Ulf Langheinrich when in fact they are only breaking down the video signal into frame-lengthed grains; 1/25th of a second or 40 milliseconds. The microsound time scale makes this claim to Granular Synthesis more poetic than truthful;

"Microsound includes all sounds on the time scale shorter than musical notes, the sound object time scale, and longer than the sample time scale. Specifically this is shorter than one tenth of a second and longer than 10 milliseconds"

GeoVideo claims to acquire "absolute coordinates at 180 fps" - this equates to 7.2 times more temporal resolution than standard 25 fps PAL video. These GeoVideo "frames" are therefore each 5.5 milliseconds in duration. To give this some context on the microsound time scale, 5 milliseconds is the duration of a honey bee’s wing flap.

Of course the problem lies in a lack of real-time playback systems for 180 fps video. No DVD player, tape player, celluloid projection system or means which doesn't involve custom hardware or a computer is capable of playing this kind of content back to an audience at its full temporal resolution. Even IMAX HD is only 48 fps.

So put plainly, even if I could make a composition of a honey bee dancing wild patterns through spacetime using Granular Motion Synthesis, I would only have the satisfaction of watching it on my laptop. Showing it to a large theater of people seems to still be a ways down the road.

More On Frame Rates

Apparently IMAX HD is shot and projected at 48 fps.

The 100fps website seems to have some answers about physical thresholds of how many frames per second we can see.

Now, just for fun, a slow-motion video of a coke can being destroyed by an arrow at 4000 fps (courtesy of Photron).

Frame Rates

Let's hit the ground running, so to speak.

This afternoon I was hanging out with the Vasulkas and we were discussing video frame rates. Basically most of us have to choose between 24, 25, or 29.97 frames per second. While these frame rates allow us the persistence of vision necessary to perceive motion, it is interesting to think about the potential of high-speed video to produce other perceptual effects.

Steina said she believed that higher (read much higher) frame rates might actually trick the brain into forgetting that the images we see are video. Perhaps create an immersive cinematic image so realistic that the brain would no longer be able to discriminate between it and reality.

Yet naturally just as there is a low end on the perceptual threshold of movement in video (two frames) there is probably also a high end. Is it 50 fps (frames per second) 100 fps, or is it way up there in the tens of thousands like audio? My guess is its somewhere below 100 fps.

Economic forces have kept us from being able to experiment with high-speed video. High-speed film has the problem that just a couple seconds takes up valuable physical space and expensive resources (film stock). Yet in today's world of relatively affordable gigabyte harddrives, the prospect of storing high-speed video is not so intimidating. Perhaps the bottleneck today is the processors and video cards we would need to playback such higher frame rate material. Ideally we would have dedicated high-speed hardware and software.

Film sound is standardized at 48,000 Hz sample rate. This means that audio is sampled forty-eight thousand times per second! And yet for video we only "sample" our images at 25 frames per second (for the sake of simplicity I will assume the PAL frame rate). When you get down to 1/25 of a second there can still be an abundance of variation and movement in sound, yet you have only a still image.

Here we have the audio information from 1/25 of a second. Seems like a lot of variation right? At this duration we get a rumbling dirty wave pattern. If we go to the smallest grain of audio we end up with a pure high-pitched tone. These fluctuations in sound are interesting. So interesting, in fact, that granular synthesis is a very popular method of contemporary electronic music composition.

Think about what Martin Arnold might have done if he had had higher frame rates. While you are pondering this, enjoy this little clip of one of my favorite things he did, despite these arbitrary limitations: