Ultra high definition television (UHDTV) is one of the hottest topics in the TV industry. Motivated by major sporting events such as the upcoming Olympic Games in Rio, broadcasters, consumer electronics manufacturers and their suppliers are working hard to make UHD solutions ready for use, perfect them and ultimately establish them on the market.
The consumer electronics industry has clearly gained the upper hand in the usual chicken-and-egg dispute this time by offering UHD cameras and TVs. Infrastructure suppliers and broadcasters are faced with the challenge of closing the producer / consumer supply gap and creating a marketable UHD ecosystem. This is no easy task, considering that data volumes have exploded due to drastically increased picture resolutions (UHD-1: 3840 × 2160 pixels; UHD-2: 7680 × 4320 pixels) and other improvements such as frame rates up to 120 fps, extended color ranges and more powerful audio formats. The goal, however, by using the HEVC (H.265) next-generation coding standard, is to achieve twice the compression efficiency of MPEG-4 (H.264) currently used in today’s HDTV. As a result, UHDTV programmes can then be broadcast via terrestrial networks. In the spring of 2013, the Korean Broadcasting System proved that this entirely feasible when it began using a transmitter from Rohde & Schwarz to regularly broadcast a UHD program in the Seoul metropolitan area.
HEVC realtime coder, multiplexer and gateway
The compact R&S®AVHE100 headend processes the 4K programme data into a transport stream that can be transmitted. The headend features the latest in high-performance data technology to perform CPU-intensive HEVC encoding in realtime. All of the headend signal flows are IP-based. This is a prerequisite for ensuring high integration density for all functions as well as extensive flexibility in functional structuring to meet individual requirements.
The UHDTV signal is fed from a 4K camera, a downstream control unit or a 4K playout server to the headend via four 3G-SDI cables (data rate: 12 Gbit/s). Unlike other solutions on the market that process the four HD image quadrants separately and only stitch them together into a full 4K picture at the end, the R&S®AVHE100 combines the quadrants prior to editing and works with complete 4K images after that. One advantage is potentially better picture quality, since the higher quality of the playout material ensures that the seams between quadrants remain invisible. In contrast, separate processing can lead to unclean interfaces depending on the quality of encoding. System scalability is another benefit of complete image processing; customers only purchase the computing power that they need. A typical configuration, for example, is designed for a 4K signal with 60 frames per second and very good picture quality. The hardware (processor performance) is tailored accordingly. Hardware can simply be added if requirements such as higher frame rates appear.
In conclusion, the R&S®AVHE100 performs the following functions:
- Synchronises the four 3G-SDI signals into a single 4K image (stitching)
- Carries out color subsampling of incoming UHD signals from 4:2:2 to 4:2:0 in line with ITU UHD-1
- Performs HEVC realtime encoding with 8-bit or 10-bit colour depth
- Generates UHDTV multiplex and PSI/SI or PSIP information
- Tags T2-MI packets with a timestamp pulled from the GPS signal as required for terrestrial single-frequency network (SFN) broadcasting
- Generates a transport stream via IP or ASI that is fed into the transmission network