Standard Codec is Enough: A Training-Free 4D Gaussian Compression with Dynamic UV Mapping

4D Gaussian Splatting (4DGS) has demonstrated advances in the dynamic scene representation. However, the time-varying attributes across frames introduce considerable storage and transmission costs, making 4DGS challenging to widely deploy. Existing compression methods struggle to obtain inter-frame residuals due to the unstructured nature of Gaussian representations, making explicit motion estimation and residual modeling inherently challenging. To address these, we propose a Training-Free 4D Gaussian Compression framework, TF4DGC, which transforms 4D Gaussian into a well-structured 2D representation, easy to estimate motion for coding, via a UV mapping. Specifically, we project 3D Gaussians onto a canonical sphere to obtain temporally consistent UV coordinates, and organize per-frame Gaussian attributes into multi-channel video sequences. This design enables the direct use of standard video codecs (e.g., AVC, HEVC) for compression, which is compatible with widespread hardware decoder support on laptops and mobile devices. Experimental results show that our method efficiently compresses both reconstructed and generated Gaussian scenarios, highlighting its general applicability. Our method offers a scalable and practical solution for 4DGS compression and facilitates real-time deployment in bandwidth constrained environments.