HD is rapidly becoming integrated into our world of live production. Many video and lighting professionals are saying the same thing: HD shows everything and hides nothing. What does this mean for the people who are developing the video content that is being used in our events today? Here’s a quick look at some of the issues involved with switching over to HD.
Until recently, most productions have been relying on video equipment with resolutions in the range of 1028 x 768 (referred to as 768p). Now, however, with HD, the resolution has been increased up to 1080p (1920 x 1080).
In Search of Excellence
CNET Editor David Katzmaier recently stated another truth about HD on cnet.com: “Despite the obvious difference in pixel count, 720p and 1080i both look great. In fact, unless you have a very large television and excellent source material, you’ll have a hard time telling the difference between any of the HDTV resolutions.” I’m using this information as the raison d’etre for this article; some of our source material is less than excellent, and we are using some very big display screens in many of our events. This is a huge issue (no pun intended).
When you have 1024 x 768 source material and render it on a studio monitor, the flaws aren’t necessarily visible or problematic because it’s only being displayed in relatively small proportions. However, when that same image is magnified and projected across millions of pixels on a 60-foot LED screen in HD, then everything is exposed. Let’s look at some of the kinds of things that appear where you least expect (and want) them. These “things” are called artifacts.
The Facts About Artifacts
What are artifacts? Here’s an overall general definition quoted from Transcode Processing: Artifacts — things that appear in your video that were not in the original source material.
These unwanted effects can include:
Moiré: an effect caused by closely spaced lines or grids showing interference patterns as the scene pans across them or displaying a shimmering effect when static.
Ringing: when a small object moves across a static background, a band of noise surrounds the object and moves with it.
Pixellation: breaking up of the picture into small flickering colored squares.
Dotcrawl: dots that appear around vertical lines when contrasted with the color red, particularly common to NTSC captures.
Blocking: could be the effect of the picture appearing to be made of little squares or the loss of detail in highly saturated areas associated with clip-ping.
In some cases, an artifact is not caused by the video source, but by the playback of the video. If the playback mechanism has insufficient horse-power for proper decoding, or if it creates excessive bitrates, it may not be capable of keeping up with the data rate. The result may be that it will drop the overflowing data. This looks like sharp-edged rectangular artifacts of random coloration. Whether the artifact shows up in the content or on the display, the result is the same: Your content doesn’t play back as expected, and you are going to have to scramble to repair the problem if your content isn’t cooperating.
The 38,000-Pound Gorilla
I recently worked on a corporate shareholders show for Wal-Mart in which several artists were scheduled to perform on an arena stage throughout the weeklong event. The video director for the band I was traveling with experienced first-hand a problem with artifacts. The band’s video content was created over the years by a variety of designers using their favorite formats, and almost all of it was rendered at lower resolutions than HD. On this particular show, there was a 38,000-pound HD LED video display rigged all the way upstage. The band’s video director did an excellent job of managing the content conversions onsite, but the process had some technical problems. She discovered that some of the oldest content was not ren-dered cleanly, and as a result, there were some artifacts in the content with which she was less than pleased. Again, she handled these issues like the pro that she is, and the video imagery was the most striking visual element in the show. And that was very important because the LED wall couldn’t be missed even if you tried.
The day when HD is everywhere is rapidly approaching. We would all do well to consider this example and get a reality check. Have you given any thought to your content development as it applies to HD? Will you be able to use your existing content when your production upgrades its ex-isting equipment? Are you thinking ahead and getting all new content created at the higher resolutions suitable for HD? Or are you putting it off into the fuzzy distant future, telling yourself that you’ll do it when you have to? If you aren’t taking steps right now to prepare yourself for that changeover, you may not be able to make the changes when you need to.
Don’t wait until you’re on site to repair the problems when you’re faced with the challenge of displaying your content on HD equipment. Do your-self a favor. Think about it now, and you won’t be kicking yourself when the time comes.
Vickie Claiborne is a freelance lighting director, programmer and trainer. She can be reached at vclaiborne@plsn.com.
