In this paper we review and summarize research results concerning video encoding parallelization, with a primary focus on medium and fine grained methods that operate at block or inner block levels. Taxonomies are illustrated wherever applicable with emphasis to scalability issues. Given the reported results, we turn our attention into the problem of allocating resources (processing cores) to parallel tasks performed by the encoder so as to achieve high speedup. We advocate that a parallelization scheme taking advantage of independently coded areas (e.g., tiles), wavefront parallelism within each area and inner block parallelism at the CTU compression level, can achieve significantly higher parallelization degree compared to standalone methods. An algorithm is then proposed that takes resource allocation decisions at all the aforementioned levels. Both the proposed algorithm and standalone representative approaches from the relevant literature are evaluated in terms of scalability using CTU coding times recorded by CU split parallelism in VTM 6.2. Results show that the potential scalability of the proposed scheme surpasses alternatives.

The emergence of the new generation video coding standard, Versatile Video Coding (VVC), has brought along novel features rendering the new standard more efficient and flexible than its predecessors. Aside from efficient compression of 8 k or higher camera-captured content, VVC also supports a wide range of applications, including computer-generated content, high dynamic range (HDR) content, multilayer and multi-view coding, video region extraction, as well as 360° video. One of the newly introduced coding tools in VVC, offering extraction and independent coding of rectangular sub-areas within a frame, is called Subpicture. In this work, we turn our attention to frame partitioning using Subpictures in VVC, and more particularly, a content-aware partitioning is considered. To achieve that, we make use of image segmentation algorithms and properly modify them to operate on a per Coding Tree Unit (CTU) basis in order to render them compliant with the standard’s restrictions. Additionally, since subpicture boundaries need to comply with slice boundaries, we propose two methods for properly partitioning a frame using tiles/slices aiming to avoid over-partitioning of a frame. The proposed algorithms are evaluated regarding both compression efficiency and image segmentation effectiveness. Our evaluation results indicate that the proposed partitioning schemes have a negligible impact on compression efficiency and video quality

One of the main targets in video surveillance systems is to detect and possibly identify objects within monitoring range. This entails analyzing the video stream, by applying object detection techniques on one or more frames. Regardless of the output, the stream is usually archived for future use. Real-time requirements, network bandwidth, and storage constraints play a significant role to total performance. As video resolution increases, so does the video stream size. To harness such an increase, newer video compression standards offer sophisticated coding tools that aim at reducing video size, with minimal quality loss. However, as the achievable compression ratio increases, so does the computational complexity. In this paper, we propose a methodology to reduce both bitrate and processing time of video surveillance streams whereby object detection is performed. The method takes advantage of tile partitioning, with the aim of (i) reducing the scope and the invocation frequency of the object detection module, (ii) encoding different blocks of a frame at different quality levels, depending on whether objects exist or not, and (iii) encoding and transmitting only tiles containing objects. Experimental results using the UA-DETRAC dataset and the VVenC encoder demonstrate that exploiting tile partitioning in the manner proposed in the paper results in reducing bitrate and processing time at the expense of only tiny losses in accuracy.