An LMM for Efficient Video Understanding via Reinforced Compression of
  Video Cubes
Authors: name: Ji Qi, name: Yuan Yao, name: Yushi Bai, name: Bin Xu, name: Juanzi Li, name: Zhiyuan Liu, name: Tat-Seng Chua

Large Multimodal Models (LMMs) uniformly perceive video frames, creating
computational inefficiency for videos with inherently varying temporal
information density. This paper present Quicksviewer, an LMM with new
perceiving paradigm that partitions a video of nonuniform density into varying
cubes using Gumbel Softmax, followed by a unified resampling for each cube to
achieve efficient video understanding. This simple and intuitive approach
dynamically compress video online based on its temporal density, significantly
reducing spatiotemporal redundancy (overall 45times compression rate), while
enabling efficient training with large receptive field. We train the model from
a language backbone through three progressive stages, each incorporating
lengthy videos on average of 420s/1fps thanks to the perceiving efficiency.
With only 0.8M total video-text samples for training, our model outperforms the
direct baseline employing a fixed partitioning strategy by a maximum of 8.72 in
accuracy, demonstrating the effectiveness in performance. On Video-MME,
Quicksviewer achieves SOTA under modest sequence lengths using just up to 5\%
of tokens per frame required by baselines. With this paradigm, scaling up the
number of input frames reveals a clear power law of the model capabilities. It
is also empirically verified that the segments generated by the cubing network
can help for analyzing continuous events in videos.