  Large-scale language-image pre-trained models (e.g., CLIP) have shown
superior performances on many cross-modal retrieval tasks. However, the problem
of transferring the knowledge learned from such models to video-based person
re-identification (ReID) has barely been explored. In addition, there is a lack
of decent text descriptions in current ReID benchmarks. To address these
issues, in this work, we propose a novel one-stage text-free CLIP-based
learning framework named TF-CLIP for video-based person ReID. More
specifically, we extract the identity-specific sequence feature as the
CLIP-Memory to replace the text feature. Meanwhile, we design a
Sequence-Specific Prompt (SSP) module to update the CLIP-Memory online. To
capture temporal information, we further propose a Temporal Memory Diffusion
(TMD) module, which consists of two key components: Temporal Memory
Construction (TMC) and Memory Diffusion (MD). Technically, TMC allows the
frame-level memories in a sequence to communicate with each other, and to
extract temporal information based on the relations within the sequence. MD
further diffuses the temporal memories to each token in the original features
to obtain more robust sequence features. Extensive experiments demonstrate that
our proposed method shows much better results than other state-of-the-art
methods on MARS, LS-VID and iLIDS-VID. The code is available at
https://github.com/AsuradaYuci/TF-CLIP.
