Question about the modified VQ-VAE implementation in this repo

[PolarisYxh]

This version modifies the VQVAE part compared to the paper version.
I am having trouble understanding the modifications made in this version.

Could you please explain:

• What are the main differences between this VQ-VAE implementation and the paper version?
• What is the motivation behind these changes?
• Is there any documentation or reference that describes this modified VQ-VAE in more detail?

If possible, could you also provide some pointers to relevant papers or resources?

Thank you for your help!