JamieG Analysis

I have been doing a lot of work in the codec area recently.

From trying to come up with a new standard for Cinema Exhibition that is cheaper then going full DCI, but as close to DCI as we can get.. To the adoption of the next generation online video codecs.

Lets look at DCI first. I will cover Web video and codec in another post.

JPEG2000 as specified by DCI is a I-frame based stream of images. Ie, each image is independant of the next. There is no TEMPERAL compression. Ie using previous or next frames to help construct the current frame. As such, DCI movies are HUGE files which can only be encoded by niche companies charging niche prices. (Ie ad a few zeros on the end of the bill).

But that is DCI and I have to admit, the quality is the best. And really, we have no other choice other then DCI at the moment. As, no current widely used codec can reproduce the colour space required for display in Cinema.

This brings us to the point that, the main issue with current codecs and Cinema Exhibition, is that, the 8bit YUV colour space is simply not good enough to reproduce the image. Being in a pitch black cinema, with a huge screen, if there are any issues with the image quality, your going to see it.

To clarify, “COLOUR SPACE” is the ability to display colours. A lack of colour space usually shows up in gradients. For example, a sky going from light blue to a darker blue. If you see graduations, or lines, this is a sign of a low colour bit depth.

I was talking to Glen, head production supervisor for DI at Peter Jacksons Post Production facility in New Zealand. Just so you know, all hi end display of film to the producer for approval is done in 10bit YUV at 1920×1080. Going to film it is recorded at 1600 lines across (Lower then HD 1920×1080) Did anyone notice the difference here on screen for Loard of the Rings or other films out of the Jackson stables? Where most under the impression that 4k was used?

A lot of this is FUD produced by the incumbent players to sell bigger and more expensive equipment. But that is off topic.

What I am getting at is that 1920×1080 is more resolution then we usually get to see in the cinema today. But we lack the colour depth in widely used video codecs.

BUT WAIT! see the following… H264 on wikipedia

Recently the specifications for H264 has been expanded to include EVERY possible requirement for archiving a DCI type experience. It is only early days, but these standards will slowly be adopted.

This is not only important for cinema but for the home user. I am amazes at the quality of DLP home theatre systems now. Images quality problems are just as evident on them.

To finish up, I just want to also mention how H.264 is known to be the best picture per byte on the internet too. (See apple.com/trailers) This leads me into another post I will cover later on H264 and web video.