High-defcorner @ SMPTE

High-defcorner @ SMPTE

David Field attends the motion picture industry’s biennial forum to see what the professionals are talking about.

SMPTE stands for the Society of Motion Picture and Television Engineers, and a fierce acronymic society like that demands fierce toys to make the films we all love watching. Every two years at Darling Harbour the industry exhibits new equipment and discusses how the industry is shaping up through a series of tech talks in audio, compression, video, distribution and hardware. Here are the highlights.

One of the most interesting presentations was made by Joe Lee (Silicon Image marketing director), who outlined every imaginable aspect of the HDMI standard up to its current version (1.3). You may already know it’s based on the DVI specification used by computers and includes audio and DRM, however the management system and revisions to the standards are where the fascinating aspects lie.

As an HDMI signal works its way through a device chain, it provides a bidirectional information link for devices, which can handshake with each other. It’s used to ferry remote control signals between devices and can correct for lip synch issues. This means that if a manufacturer has made a display with measurable input lag (the time in milliseconds between receiving a signal and displaying it) it will inform other devices in the chain when handshaking, and then compensate. In practice, this means your amplifier will offset the audio by whatever the display tells it so that the audio and video arrive in synch.

One of the concerns about HDMI is that because it was developed as a computer interconnect, signal degradation would occur as cables became longer – a worry for roof mounted projectors. However, Joe assured attendees that runs of up to 20 meters should work, and 30 meters should be achievable with the use of equalisation to compensate for the way signals degrade over distance in unshielded HDMI cables.

Digital broadcasting
Australian digital broadcasts still use an MPEG-2 based system introduced in 2001. Even though it makes technical sense for the industry to switch to MPEG-4 and save on bandwidth, this won’t happen for some time: speakers agreed that until MPEG-4 could demonstrate a 2:1 bandwidth saving over the old MPEG-2 standard, it would be too hard to convince people to buy new MPEG-4 decoders.

Foxtel, however, owns the broadcast infrastructure from its offices to the set top boxes in its customers’ homes. It will, therefore, have an easier task of switching to MPEG-4 than the free-toair broadcasters, and HD content will help facilitate the switch. Nonetheless, all the providers will have to find a way to provide a better service as well as a better picture before being able to convince people to get a new set top box.

One possible way of selling new decoders may lie in digital video recorders (DVRs). If MPEG-4 can provide an image comparable to MPEG-2, DVR’s would be able to record twice the content onto an equivalent hard drive. This, combined with the additional content that could be delivered and more consumer choice, could be the driving force behind MPEG-4.

At the movies
Digital cinematography (and how to handle its massive 1GB/s data rate) was also a hot topic at SMPTE. The simplified workflow and absence of grain and jitter is a huge bonus, but the sensitivity of the sensors in modern digital cinematography cameras can’t match high sensitivity film yet. The DaVinci Code was shot on film for this reason: lights weren’t permitted in the Louvre’ as they would damage the paintings, and digital film didn’t have the necessary dynamic range to shoot effectively without additional lighting.

While new cameras and sensors (from Red and Sony) are trying to address this, the industry is implementing new codecs to solve the size problems. Red has its RedCode, Avid has DNxHD and Apple has ProRes 4:2:2, which is suitable for TV and documentaries, but not film.

The third dimension
Barco exhibited its 2K projector and Real D's 3D cinema system: a fascinating take on 3D imaging. Typically, a 3D setup works by shooting a scene with two synchronised cameras positioned side by side. When the footage makes it to a projector, the image alternates from frame to frame between the first and second camera. A system then filters the footage so that the footage from one camera only enters the left eye, and the other camera the right eye. The end result is the illusion of 3D images.

Old red/green glasses are a classic example; however a better demonstration is the IMAX system which issues a chunky headset with an LCD display in front of each eye to each audience member. The displays pulse on and off in time with the projector so that the frames from the two different cameras alternate between each eye, creating a 3D image.

Real D takes a different approach. In front of the projector’s lens is an electronically controlled filter, which polarises frames in one of two directions depending on which camera they originate from. The viewer wears a pair of lightweight glasses containing two passive directional polarising filters. They siphon the cameras’ output into the eyes of the viewer, creating the illusion of 3D.

The projector that the system was strapped to is huge, as you can see below. The projector component comprises the top section and the managment system is housed in the bottom section. The main differences between this and a domestic projector is the colossal amount of light it throws, its utterly accurate high bit depth colour, and its resolution. Almost all movies, regardless of whether they are shot on film or digital, are displayed in 2K resolution after scanning or post production.

click to view full size image

Projectors like this are calibrated to display an identical image regardless of the cinema they are used in, which is why Peter Jackson uses one as a live display in his post production facility. It ensures that what he sees in his cinema will be reproduced exactly on all cinemas equipped with digital projectors.

New cameras
Panasonic introduced its new AVCIntra codec for its P2 line of cameras, which record to memory cards in a PC Card housing instead of tape. The innovative concept was debuted three years ago, but older cameras were only able to record in DVCPro 25, 50 or HD. Those numbers refer to the bitrates used by the codec, with DVCPro HD’s bitrate being 100 Mb/s. The problem with the P2 system has been storage, as the robust cards used currently ship at a maximum of 16GB. That translates to 16 minutes of footage per card in HD. But capacities will soon double while prices remain static.

Sony introduced a new handheld XDCAM EX camera, which unlike previous shoulder mounted models (which record to a Blu-ray disc in a ruggedized caddy), records to ExpressCard/34. It still uses the XDCAM codec (which has a bitrate of 35Mb/s) and can support overand under-cranking for fluid slow and fast motion.

Sony also exhibited a remote controlled helicopter with a small camera mount attached. But this was eclipsed by the shock and awe value of a fully giro-stabilised Panavision cinematography camera attached to a Eurocopter 350B Squirrel.

A non-working sample of the new Red Camera was unveiled at Apple’s booth. It looks like something out of the film, Alien, and if Red’s plans come to fruition, it is set to rival the biggest, meanest cameras from Arri and Panavision for a paltry $35,000. For comparison, the competition’s cameras sell for around $1,000,000.

On the completely-out-of-theblue-and-extraordinarily-cool front was Amber Technology’s fully robotic Fusion camera pedestal. You control it remotely with two joysticks and an assortment of buttons, and it also gives you complete control of the camera.

Finally, another stunning exhibit was the roll up reflective chroma key screen. Once you’ve positioned and ‘lit your talent’ in front of it, you attach a ring of green LEDs outside the lens of a camera. The light from the LEDs uniformly bounces off the reflective screen, then back into the lens while being obscured by the talent, giving you a perfect key.

This feature appeared in the September 2007 issue of PC & Tech Authority Magazine

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