Recently, 3D Gaussian Splatting (3DGS) has emerged as a promising scene representation technique for novel view synthesis. However, the large number of Gaussians used to represent the 3D scene poses challenges for storage and transmission. Existing advanced compression methods focus on designing various context models for entropy modeling, but lack the exploration of prediction techniques. In this paper, we dig into feature correlations in the anchor-based Gaussian representation and propose two types of feature prediction techniques to further reduce the scene redundancy. Firstly, we observe that context features contain rich scene priors, which are also helpful for reconstruction but often ignored by previous methods. To this end, we design a Context-based Weighted Prediction module to adaptively aggregate the anchor feature and the context feature for rendering, which can reduce the storage costs in anchors. Secondly, a high degree of similarity is discovered between different feature channels. To utilize the cross-channel correlations, we propose a Cross-channel Residual Prediction module, which further reduces the bit cost for coding anchor features. Extensive experiments show that our method can further enhance compression performance while maintaining rendering quality compared to existing 3DGS compression methods. Our code is available at https://github.com/Pomelomm/FP-GS.

The rapid advancement of immersive visual applications has drawn significant attention to multi-view video compression. However, no end-to-end learning compression model is proposed for multi-view video sequences with six degrees of freedom. In this paper, we first propose an end-to-end model MVCNet to enhance multi-view video compression performance as shown in Fig. 1. MVCNet eliminates spatial and temporal redundancy in multi-view data effectively. In our methods, an efficient encoding structure is designed for compression, which utilizes spatial and temporal information among frames and views to improve compression performance. Furthermore, we propose a hybrid prediction module, which combines different prediction methods to provide satisfactory images and reduce the bit rate. Besides, we demonstrate a strategy of the fusion network to perform adaptive reconstruction.

Recently, 3D Gaussian Splatting (3D-GS) techniques have effectively driven the development of novel view synthesis due to the fast rendering speed and high-quality rendering. In this paper, we propose a compressed 3D Gaussian splatting model with residual rendering to enhance rendering quality and reduce storage. In our model, we design a residual rendering strategy to enrich the scene details, which leverages residual Gaussian points to optimize basic Gaussian points and supplement missing information. Additionally, an octree-based geometric compression model is introduced to compress geometric location.

Scalable coding, which can adapt to channel bandwidth variation, performs well in today's complex network environment. However, most existing scalable compression methods face two challenges: reduced compression performance and insufficient scalability. To overcome the above problems, this paper proposes a learned fine-grained scalable image compression framework, namely DeepFGS. Specifically, we introduce a feature separation backbone to divide the image information into basic and scalable features, then redistribute the features channel by channel through an information rearrangement strategy. In this way, we can generate a continuously scalable bitstream via one-pass encoding. For entropy coding, we design a mutual entropy model to fully explore the correlation between the basic and scalable features. In addition, we reuse the decoder to reduce the parameters and computational complexity. Experiments demonstrate that our proposed DeepFGS outperforms previous learning-based scalable image compression models and traditional scalable image codecs in both PSNR and MS-SSIM metrics.

Recently, learned video compression (LVC) has shown superior performance under lowdelay configuration. However, the performance of learned bi-directional video compression (LBVC) still lags behind traditional bi-directional coding. The performance gap mainly arises from inaccurate long-term motion estimation and prediction of distant frames, especially in large motion scenes. To solve these two critical problems, this paper proposes a novel LBVC framework, namely L-LBVC. Firstly, we propose an adaptive motion estimation module that can handle both short-term and long-term motions. Specifically, we directly estimate the optical flows for adjacent frames and non-adjacent frames with small motions. For non-adjacent frames with large motions, we recursively accumulate local flows between adjacent frames to estimate long-term flows. Secondly, we propose an adaptive motion prediction module that can largely reduce the bit cost for motion coding. To improve the accuracy of long-term motion prediction, we adaptively downsample reference frames during testing to match the motion ranges observed during training. Experiments show that our L-LBVC significantly outperforms previous state-of-the-art LVC methods and even surpasses VVC (VTM) on some test datasets under random access configuration.

In neural video codecs, current state-of-the-art methods typically adopt multi-scale motion compensation to handle diverse motions. These methods estimate and compress either optical flow or deformable offsets to reduce inter-frame redundancy. However, flow-based methods often suffer from inaccurate motion estimation in complicated scenes. Deformable convolution-based methods are more robust but have a higher bit cost for motion coding. In this paper, we propose a hybrid context generation module, which combines the advantages of the above methods in an optimal way and achieves accurate compensation at a low bit cost. Specifically, considering the characteristics of features at different scales, we adopt flow-guided deformable compensation at largest-scale to produce accurate alignment in de-tailed regions. For smaller-scale features, we perform flow-based warping to save the bit cost for motion coding. Furthermore, we design a local-global context enhancement module to fully explore the local-global information of previous reconstructed signals. Experimental results demonstrate that our proposed Hybrid Local-Global Context learning (HLGC) method can significantly enhance the state-of-the-art methods on standard test datasets.