  Online video streaming has fundamental limitations on the transmission
bandwidth and computational capacity and super-resolution is a promising
potential solution. However, applying existing video super-resolution methods
to online streaming is non-trivial. Existing video codecs and streaming
protocols (\eg, WebRTC) dynamically change the video quality both spatially and
temporally, which leads to diverse and dynamic degradations. Furthermore,
online streaming has a strict requirement for latency that most existing
methods are less applicable. As a result, this paper focuses on the rarely
exploited problem setting of online streaming video super resolution. To
facilitate the research on this problem, a new benchmark dataset named
LDV-WebRTC is constructed based on a real-world online streaming system.
Leveraging the new benchmark dataset, we proposed a novel method specifically
for online video streaming, which contains a convolution and Look-Up Table
(LUT) hybrid model to achieve better performance-latency trade-off. To tackle
the changing degradations, we propose a mixture-of-expert-LUT module, where a
set of LUT specialized in different degradations are built and adaptively
combined to handle different degradations. Experiments show our method achieves
720P video SR around 100 FPS, while significantly outperforms existing
LUT-based methods and offers competitive performance compared to efficient
CNN-based methods.
