NHK is progressing with the development of equipment to enable to the broadcast of 8K Ultra High Definition television, with trial broadcasts to begin in Japan in 2016.
The camera head, co-developed with Astrodesign, has been made much lighter and more compact. They achieved this by packaging a 33-megapixel image sensor and its drive circuits in a housing just 10 cm square, with a total weight of around 2kg.
“The image sensor is small, just 25 mm diagonally. So, the lens can be made small, too. In particular, this lens is used for digital cinema, but it’ll also be usable for Ultra HD. So, a feature of this system is, it can be made very small overall.”
“The monitor has 4K resolution, but the signal processing is 8K. The image sensor itself can run at 120 Hz, but the signal processing component isn’t ready yet. So here, the display is running at 60 Hz.”
NHK, in collaboration with Mitsubishi Electric, has also developed the world’s first HEVC/H.265 real-time encoder for 8k Ultra HD.
HEVC is the latest video encoding system, which became an international standard this year. It has four times the compression efficiency of MPEG2, widely used in current digital HD broadcasting.
“This video is encoded at 85 Mbps. Considering the encoder input, it’s being compressed from 30 Gbps by a factor of 1/350. To encode Ultra HD video, which has very high resolution, encoding is done in real time by dividing the screen into 17 strips. Compression to 85 Mbps enables one Ultra HD channel to be transmitted using one satellite transponder.”
Information about the speed and direction of moving objects is shared across several segments, which minimizes loss of picture quality where segments join.
Currently, the encoding is done at 60 Hz, but NHK plans to work on 120 Hz real-time encoding, which is a part of the Ultra HD specifications.