Online-trained Upsampler for Deep Low Complexity Video Compression

Deep learning for image and video compression has demonstrated promising results both as a standalone technology and a hybrid combination with existing codecs. However, these systems still come with high computational costs. Deep learning models are typically applied directly in pixel space, making them expensive when resolutions become large. In this work, we propose an online-trained upsampler to augment an existing codec. The upsampler is a small neural network trained on an isolated group of frames. Its parameters are signalled to the decoder. This hybrid solution has a small scope of only 10s or 100s of frames and allows for a low complexity both on the encoding and the decoding side. Our algorithm works in offline and in zero-latency settings. Our evaluation employs the popular x265 codec on several high-resolution datasets ranging from Full HD to 8K. We demonstrate rate savings between 8.6% and 27.5% and provide ablation studies to show the impact of our design decisions. In comparison to similar works, our approach performs favourably.