The WOW! Buzz

As promised in the last post, we attack the subject of “judder” and how it relates to HDTV and the movie experience generally. As a young man, I became involved with a community movie theatre, one of those grand old theatres built in wonderful art deco style in the 50’s. It was a restoration project of sorts–efforts were made to preserve wonderful architectural elements while updating seating, old projection and sound systems. My specific assignment was to rebuild the sound system to THX specifications, but I managed to learn quite a bit about projection systems and the cinematic art generally in the process.

I learned, for example, that optical projection of film was at 24 frames per second, and had been since the advent of the “talkies”–apparently with the technology of the time, that speed was required to effectively record a sound track on the film. In the silent era, frame rates were even slower–around 16 frames per second. Optical projection equipment built in the last few decades has typically flashed each frame on the screen twice, effectively creating 48 frames per second, although with no real addition to visual information.

This cinematic frame rate, slow as it is, has been touted as the “gold standard” for video by some, and is the frame rate for many movies on Blu-ray. Ironically, cinematographers have worked for years to minimize jerking artifacts associated with this rather slow frame rate, usually observed in fast pans or other motion on screen. Some filmmakers claim to have utilized this motion shudder (called “judder”) to specific artistic effect over the years.

So the debate rages. Is video better if it stays absolutely true to the film-based standard? Artifacts and all? Does the conversion of 24 fps to 30 or 60 fps (the current video standards) compromise the artistic integrity of the filmmaker?

Here’s the thing. In theory anyway, conversion of a 24 fps film to 60 fps (typical of most modern sets–remember the discussion around 60 Hz refresh rates last post) should introduce artifacts to the viewing experience, because in the conversion process, three identical frames are displayed, then two of the next frame, then again three, then two, and so on. This “3:2 sequence” repeats 12 times a second, creating 60 frames per second typical of a modern HDTV (this conversion process is called 3:2 pulldown). Video purists have complained about this compromise, and it does look different than the original film–whether it’s better or worse is up for debate.

Enter sets that refresh 120 times a second, also discussed in my last post. Here the conversion from 24 fps is mathematically smoother–each frame is displayed 5 times before moving on to the next–five times 24 equals 120 frames per second. Again, in theory, because the conversion is absolutely symmetrical, the 120 Hz set should have greater fidelity with film based content.

Enter yet another technical innovation on the modern HDTV set–”anti-judder” technology. Certain manufacturers of high end sets have posed the question, “Why do we have to display five identical frames then jump to the next frame?” The answer is, “You don’t!” Digital processing technology can compare two frames and extrapolate video information, painting four additional “transition” frames between the two actual frames of video information. And indeed, Sony Toshiba, and others have proprietary technology available in their high end sets that does exactly that, effectively creating a very smooth image on screen that is rock solid to the human eye. All frame to frame disjunct is gone, pans and fast motion sequences are smooth as butter-on-rye. No more judder!

This is an evolving technology, and some systems are better than others. But as with any innovation, some like the effect, some don’t, claiming that it compromises the filmmaker and his art. Bah!

My personal opinion is that the 24 fps standard, largely adopted as a compromise in the first place to save expensive film costs, should go down the road. In years ahead, I think we will look at 24 fps as an anachronism from another time–quaint, but not the best for a top notch viewing experience. As “film” production migrates more and more to production using high definition video technology, 60 fps will, I hope, become the gold standard. I can hardly wait to see what the artists and producers will do with better tools.