Support Blosc2 codec

[eschnett]

Zarr supports the Blosc library as a codec https://zarr-specs.readthedocs.io/en/latest/v3/codecs/blosc/v1.0.html . Blosc is now somewhat outdated, and a successor Blosc2 exists. It would be nice if Blosc2 was supported as a codec as well.

Since both the APIs and the container (on-disk) formats changed between Blosc and Blosc2, it might be best to support Blosc2 as a new codec.

Is this a good idea? How would I go about proposing this officially? At the technical level, I assume that actually writing the specification and opening a pull request would be a step towards receiving feedback?

[jhamman]

There are some active threads on the subject already:

• Blosc2 Codec? numcodecs#413
• Caterva inside Zarr #713

Okay if we close this in favor of those open issues?

[sanketverma1704]

Also adding zarr-developers/numcodecs#463 to the list.