Mobile receiver design increases the resolution of compressed video

Abstract

When compressing a video sequence, modern techniques achieve high compression ratios by removing image details (high-frequency information), producing a degradation of the decoded image. This degradation is negligible for high bit rates but can result in unbearable quality where bit rates are very low and compression ratios must therefore be high. Sometimes the lost information can be recovered from frames that occur shortly before or after the one that is degraded. This is known as superresolution (SR) but its high computational load usually prevents real-time implementation of the process. Moreover, such algorithms are designed in such away that a feasible implementation would require a huge re-design effort. Although several algorithms for SR have been proposed (a comprehensive classification is provided by Borman1), all lack a practicable real-time implementation: for those who know the field, this even includes the Segall2 and Gunturk3 compression environments. Here, we jointly consider the algorithm specification and the system design as a whole process, where the restrictions imposed by the platform are taken into account by the algorithm from the first design steps. Our aim is to contribute towards research in low-cost and high-performance multimedia devices. To this end, we propose a mobile system for realtime video reception over the Digital Audio Broadcast4 (DAB) network, using programmable logic devices (PLDs) with embedded microprocessors as the target technology. As the data rate of DAB is limited to 1.8432Mbs−1, the bandwidth of the encoded sequence must be drastically reduced, decreasing the quality due to compression losses. To increase the image quality for these very-low bit rates, we have developed a novel technique that we call extended Figure 1. Overview of a system to improve the quality of highlycompressed video images.