  While recent years have witnessed great progress on using diffusion models
for video generation, most of them are simple extensions of image generation
frameworks, which fail to explicitly consider one of the key differences
between videos and images, i.e., motion. In this paper, we propose a novel
motion-aware video generation (MoVideo) framework that takes motion into
consideration from two aspects: video depth and optical flow. The former
regulates motion by per-frame object distances and spatial layouts, while the
later describes motion by cross-frame correspondences that help in preserving
fine details and improving temporal consistency. More specifically, given a key
frame that exists or generated from text prompts, we first design a diffusion
model with spatio-temporal modules to generate the video depth and the
corresponding optical flows. Then, the video is generated in the latent space
by another spatio-temporal diffusion model under the guidance of depth, optical
flow-based warped latent video and the calculated occlusion mask. Lastly, we
use optical flows again to align and refine different frames for better video
decoding from the latent space to the pixel space. In experiments, MoVideo
achieves state-of-the-art results in both text-to-video and image-to-video
generation, showing promising prompt consistency, frame consistency and visual
quality.
