Debates about resolution and formats have been the stuff of holy wars since video first appeared on the scene. The newest battle in this age-old debate is about the DI process.I recently had the chance to sit down with Juan Carlos Astoquillca, director of engineering at Sherman Oaks, Calif.-based Global Entertainment Partners and go through a series of side-by-side and split-screen comparisons of 2K images vs. uncompressed 4:4:4 HD RGB.Now, there are people who may say I’m blind as a bat, but to be perfectly honest, I just can’t see the difference. And you can’t really blame me: A 2K image is 2048×1556. An HD RGB image is 1920×1080. The difference in horizontal resolution is almost negligible—128 lines. Vertically, there is a bit of a trade-off, but it’s less than 500 lines.Also, a pristine 2K film scan will include image information from edge to edge (including the film’s sprocket holes)—information that is destined to be cropped for output to film’s aspect ratios of 1.85:1 or 2.37:1. The result is that the difference is almost imperceptible, unless you zoom in and blow up a tiny little area.Since both offer 10-bit, 4:4:4 color, the real difference is that 2K is data—a computer file–while the other is high-definition video. It’s often a confusing distinction, but an important one.A lot of people still think that high-definition video is data. But just because it’s digital, doesn’t mean it’s data.Video owes its legacy to tape. Data resides in the computer world. One leads to a video-centric post workflow—one that’s been in use in post for over 10 years with 4:2:2 HD video. The other leads to a data-centric workflow, which is still kind of a new beast.But even if you’re shooting on film, you can still use the 4:4:4 RGB post process. You’re not locked into 2K.“There are several benefits to the 4:4:4 RGB workflows over 2K. If a project is shot on film, 4:4:4 assembly and color correction infrastructures are much faster and more cost-effective than the same workflow in 2K. The 4:4:4 RGB workflow basically exists in most high-end HD facilities already, at a cost basis very similar to HD 4:2:2,” explained Astoquillca.The implications for post are that HD video facilities can upgrade their infrastructure very cheaply, to compete against the more filmic post houses, which have to spend a small fortune building networks to accommodate 2K data.“Repurposing infrastructures saves capital investment, bringing price down and making the DI process more accessible to everyone,” said Astoquillca.It’s an approach that is really taking off in post, and for the past year, Sony has been struggling to keep up with demand for its SRW-5500 VTR.“Demand escalated so fast. It was faster than any of us expected,” said Rick Harding, Sony’s marketing manager, Content Creation Systems. “You have to plan well in advance to make sure that production can meet that demand. We’re making those adjustments, but we have had a couple months where we’ve had less inventory than we would like.”Some high-end post houses will tell you that, technically, HD RGB isn’t really a digital intermediate because it isn’t 2K data. But whether it is a DI or not is really a question of semantics. The facilities that have built an RGB 4:4:4 postproduction infrastructure won’t hesitate to sell it as a DI pipeline, and as a result there’s a lot of confusion out there right now about what constitutes a DI. Purists will argue that it’s a sign that the buzzword DI has been overused and diluted to the point that it’s no longer helpful.Regardless, for a producer sitting there with budget estimates in hand, that one is going to stand out as a place where he can save some money, reckoning that people probably won’t notice the difference anyway.
Written by Scott Lehane
