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19 After joining VITEC in 2003, he progressed through roles in electronic design engineering, field application engineering, product and project management. These days, as a senior product manager he is responsible for a family of video encoders and decoders, in self-contained form factors (rugged and professional-grade enclosures) and as cards integrated into rack chassis. Hardware encoders VITEC’s encoders and decoders implement industry standards such as H.264 AVC, HEVC (High Efficiency Video Coding), MPEG 2 and MPEG 4, in applications that face the greatest challenges in terms of comms bandwidth along with size, weight and power constraints, such as the ROV project alluded to above. Bernard emphasises that these codecs are in hardware rather than software form, although the company does offer software encoders for less demanding applications. Able to maintain visual quality at about half the bit rate of H.264 AVC, HEVC is the latest of these standards and has been gaining ground steadily since it was first issued in 2013, although it has been held back to some extent by the limitations of software-based coding technologies tasked with live encoding of high-resolution video streams. VITEC has focused on delivering HEVC’s potential through its hardware encoders, which enable the full use of tools incorporated into HEVC. These tools include a smarter coding block structure, increased use of intra-prediction modes, better motion vector prediction and an improved anti-distortion filter. Unpacking this a little, video is compressed by eliminating redundant information from the image sequence by finding similarities between blocks within frames. HEVC assumes that blocks that are close to each other in time and space will be similar, subtracting the similarities from the information to be encoded. For example, HEVC improves motion prediction and inter-image prediction without explicit transmission of motion vector data using a mode known as ‘merge’ that incorporates a bandwidth- saving ‘skip’ mode. This mode must be used selectively, and VITEC’s encoder logic avoids unsuitable picture skipping while keeping the transmission within bitrate limits when preserving image content becomes difficult. The encoding logic also includes a rate control module that computes a larger number of parameters to optimise bit consumption, preventing bitrate overflow and avoiding severe degradation of video quality during difficult scene changes or transitions from simple to complex scenes. A hardware encoder is one whose logic is built into a specialised chip rather than held in a storage medium and executed by a general-purpose processor, which has a number of key advantages. Bernard explains, “The architectures of our encoders are usually the same, and there is obviously software to receive a command from the user, run the web server for controlling our codec and for managing information coming from the network, but underneath it controls a hardware codec that is very deterministic because we can control all the logic gates so we know exactly what it does. “If you were to do the encoding in software you’d be faced with threads, delays and requests from the user that could interfere with the whole process. So it is very hard or even impossible to achieve the kind of performance we need using software codecs.” That performance is defined by latency and bandwidth, and Bernard emphasises that development teams always remain within the bounds of the standards Richard Bernard | In conversation Creating products for video is very tangible work. Video accounts for 70-80% of global comms bandwidth, so compression obviously matters Unmanned Systems Technology | June/July 2021 As an intern at Airbus, Bernard was responsible for developing the throttle control logic for the A380 super-jumbo (Courtesy of Airbus)