In low bit-rate packet-based video communications, video frames may have very small size, so that each frame fills the payload of a single network packet; thus, packet losses correspond to whole-frame losses, to which the existing error concealment algorithms are badly suited and generally not applicable. In this paper, we deal with the problem of concealment of whole frame-losses, and propose a novel technique which is capable of handling this very critical case. The proposed technique presents other two major innovations with respect to the state-of-the-art: i) it is based on optical flow estimation applied to error concealment and ii) it performs multiframe estimation, thus optimally exploiting the multiple reference frame buffer featured by the most modern video coders such as H.263+ and H.264. If data partitioning is employed, by e.g., sending headers, motion vectors, and coding modes in prioritized packets as can be done in the DiffServ network model, the algorithm is capable of exploiting the motion vectors to improve the error concealment results. The algorithm has been embedded in the H.264 test model software, and tested under both independent and correlated packet loss models with parameters typical of the wireless environment. Results show that the proposed algorithm significantly outperforms other techniques by several dBs in peak signal-to-noise ratio (PSNR), provides good visual quality, and has a rather low complexity, which makes it possible to perform real-time operation with reasonable computational resources.Index Terms-Optical flow estimation, packet-based video transmission, video error concealment, whole-frame losses, wireless communications.

No abstract

Tears of peroneus brevis tendon represent a cause of underdiagnosed lateral ankle pain and instability. The typical clinical presentation is retro-malleolar pain, in some cases associated with palpable swelling around the fibular malleolus, pain during activities and difficulty in walking. We present a case of peroneus brevis split lesion with superior peroneal retinaculum avulsion in a young athlete who referred to the emergency ward of our hospital for left ankle pain after an inversion injury. An early diagnosis allowed treating the injury and promptly resuming sport activity, after rehabilitation training. Surgical reconstruction key-points and post-surgical follow-up were also discussed. A late diagnosis would have caused a symptomatology worsening and an increased recovery time.

No abstract

No abstract