Ster Kinekor digital cinema tech details revealed

Ster-Kinekor recently announced that it has launched a project to convert all 438 of its cinemas to the latest digital technology, and has told MyBroadband that it aims to do so in 6 months.

According to Ster-Kinekor, among the benefits offered by this conversion are improved picture quality and state-of-the-art surround sound.

In an interview following the announcement of the digital conversion project, Ster-Kinekor CEO Mario Dos Santos revealed the technical details of the new equipment they are installing.

Resolution and framerate

Ster-Kinekor uses a mix of 2K and 4K projectors, and all 2K projectors can display a maximum resolution of 2048×1080, Dos Santos said.

This means that the digital micromirror device (DMD) in the projector comprises a matrix of 2048×1080 microscopic mirrors that produce a picture made up of 2,211,840 pixels. The films themselves don’t actually use the full resolution supported.

“Films are presented in two formats – either Scope or Flat resolution,” Dos Santos said. The Scope format runs at a resolution of 2048×858, while the Flat format uses 1998×1080.

This means that in both Scope and Flat resolution there are pixels on the DMD that are not used, but the resolution of 2048×1080 lets the DMD show both formats in their native resolution without the need for scaling.

Dos Santos said that the 4K projectors that are installed at cinema sites such as Sandton City and Gateway can accommodate resolutions of up to 4096×1714 (Scope) or 3996×2160 (Flat).

Asked what framerates are supported, he said that the normal frame rate is 24 frames per second (fps), but with the new digital technology their projectors are able to accommodate high frame rate (HFR) content of up to 60fps.

The Hobbit: An Unexpected Journey is the first feature film with wide release to use HFR, and was filmed in 48fps.

Audio & video codecs

Dos Santos said that the files used by the digital projectors that Ster-Kinekor is rolling out use digital cinema packages (DCPs).

“There are various programs that can encode DCP; a collection of files that contain a video stream, audio stream, sub-title stream and metadata,” explained Dos Santos.

Video is encoded using the JPEG2000 codec and XYZ colour spacing, while the audio stream uses uncompressed 24-bit pulse code modulation at a sampling frequency of 48kHz.

File sizes

A normal 2-hour 2D film takes up about 160GB of space, Dos Santos said.

When asked how the file size changes for 3D and HFR movies, Dos Santos said that the JPEG compression makes calculating other formats based on the 2D version difficult, as JPEG only encodes pixels that change and not the full frame.

For this reason, 3D animation is usually only slightly more than the 2D version, while 3D live action is almost double the 2D version, Dos Santos said.

A similar scenario unfolds for HFR, he added. Although there are more frames per second it does not necessarily translate into more pixel changes per second.

Getting digital movies to the cinema

Despite the move to digital media, Ster-Kinekor does not download the movies it plans to screen in its cinemas from the content owners.

Instead, they import a hard-drive containing the film, which is then sent around to each site where it is scheduled to be screened.

Ster-Kinekor said that it would eventually move to distributing the film to its cinemas using fibre or satellite rather than sending physical drives around the country.

Asked how they prevent movies from being copied off the drives or projectors, Dos Santos said that each film on the hard drive is password protected per site and allocated to a specific projector in a specific theatre.

“It is also not possible to remove the digital file of the film from the projector as it is securely loaded under this encryption technology,” he said.

More cinema and movie-watching articles

Ster Kinekor: new movies in SA sooner

3D theatres: Ster Kinekor versus Nu Metro

iTunes Movies now in SA

Mobile device boom no threat to movie theatre growth: Imax CEO

DStv Explora vs HD PVR