Different from natural videos, screen content videos (SCVs) often exhibit homogeneous regions, abrupt content changes, and high prevalence of repetitive patterns. Existing deep learning (DL)-based video compression methods inadequately address the unique characteristics of SCVs, resulting in suboptimal compression performance. Therefore, in this paper, a dedicated deep screen content video compression (DSCVC) framework is proposed based on the motion and content characteristics of SCVs, which includes superpixel-constrained a motion estimation (SCME) module and inter and intra context aggregation (I2CA) module. The SCME is designed to construct a superpixel-based representation of homogeneous regions, leveraging the global correlations among superpixels to effectively capture large-scale motions, which efficiently improves the compression performance. I2CA is developed to jointly utilize inter and intra contexts, which employs a gating mechanism for content-aware context fusion, dynamically aggregating more similar contexts within SCVs. This allows for flexible adaptation to both contiguous and abrupt content changes within SCVs. Furthermore, by leveraging both learnable window and pixel displacements, a displacement-guided window attention mechanism is implemented in I2CA for precise long range repetitive feature localization, thereby reducing redundancy caused by repetitive patterns. To the best of our knowledge, it is the first DL-based video compression framework specifically designed for SCVs. Extensive experimental results demonstrate that the proposed DSCVC significantly outperforms existing methods in terms of compression performance, achieving a bitrate saving of 26.82% compared to VVC and a bitrate saving of 12.30% compared to SOTA DL-based methods.

Recently, learned video compression (LVC) is undergoing a period of rapid development. However, due to absence of large and high-quality high dynamic range (HDR) video training data, LVC on HDR video is still unexplored. In this paper, we are the first to collect a large-scale HDR video benchmark dataset, named HDRVD2K, featuring huge quantity, diverse scenes and multiple motion types. HDRVD2K fills gaps of video training data and facilitate the development of LVC on HDR videos. Based on HDRVD2K, we further propose the first learned bit-depth scalable video compression (LBSVC) network for HDR videos by effectively exploiting bit-depth redundancy between videos of multiple dynamic ranges. To achieve this, we first propose a compression-friendly bit-depth enhancement module (BEM) to effectively predict original HDR videos based on compressed tone-mapped low dynamic range (LDR) videos and dynamic range prior, instead of reducing redundancy only through spatio-temporal predictions. Our method greatly improves the reconstruction quality and compression performance on HDR videos. Extensive experiments demonstrate the effectiveness of HDRVD2K on learned HDR video compression and great compression performance of our proposed LB-SVC network. Code and dataset will be released in https://github.com/sdkinda/HDR-Learned-Video-Coding.