  Large Language Models(LLMs) have shown remarkable emergent abilities in
unifying almost all (if not every) NLP tasks. In the human motion-related
realm, however, researchers still develop siloed models for each task. Inspired
by InstuctGPT, and the generalist concept behind Gato, we introduce AvatarGPT,
an All-in-One framework for motion understanding, planning, generations as well
as other tasks such as motion in-between synthesis. AvatarGPT treats each task
as one type of instruction fine-tuned on the shared LLM. All the tasks are
seamlessly interconnected with language as the universal interface,
constituting a closed-loop within the framework. To achieve this, human motion
sequences are first encoded as discrete tokens, which serve as the extended
vocabulary of LLM. Then, an unsupervised pipeline to generate natural language
descriptions of human action sequences from in-the-wild videos is developed.
Finally, all tasks are jointly trained. Extensive experiments show that
AvatarGPT achieves SOTA on low-level tasks, and promising results on high-level
tasks, demonstrating the effectiveness of our proposed All-in-One framework.
Moreover, for the first time, AvatarGPT enables a principled approach by
iterative traversal of the tasks within the closed-loop for unlimited
long-motion synthesis.
