FlowVid: Taming Imperfect Optical Flows for Consistent Video-to-Video
  Synthesis
Authors: name: Feng Liang, name: Bichen Wu, name: Jialiang Wang, name: Licheng Yu, name: Kunpeng Li, name: Yinan Zhao, name: Ishan Misra, name: Jia-Bin Huang, name: Peizhao Zhang, name: Peter Vajda, name: Diana Marculescu

Diffusion models have transformed the image-to-image (I2I) synthesis and are
now permeating into videos. However, the advancement of video-to-video (V2V)
synthesis has been hampered by the challenge of maintaining temporal
consistency across video frames. This paper proposes a consistent V2V synthesis
framework by jointly leveraging spatial conditions and temporal optical flow
clues within the source video. Contrary to prior methods that strictly adhere
to optical flow, our approach harnesses its benefits while handling the
imperfection in flow estimation. We encode the optical flow via warping from
the first frame and serve it as a supplementary reference in the diffusion
model. This enables our model for video synthesis by editing the first frame
with any prevalent I2I models and then propagating edits to successive frames.
Our V2V model, FlowVid, demonstrates remarkable properties: (1) Flexibility:
FlowVid works seamlessly with existing I2I models, facilitating various
modifications, including stylization, object swaps, and local edits. (2)
Efficiency: Generation of a 4-second video with 30 FPS and 512x512 resolution
takes only 1.5 minutes, which is 3.1x, 7.2x, and 10.5x faster than CoDeF,
Rerender, and TokenFlow, respectively. (3) High-quality: In user studies, our
FlowVid is preferred 45.7% of the time, outperforming CoDeF (3.5%), Rerender
(10.2%), and TokenFlow (40.4%).