LZ4 Codec

[jakirkham]

Currently there is not an LZ4 Codec. There is a Blosc Codec that can use LZ4. However there is value in having a LZ4 Codec in its own right as this is a common compressor.

Note: This could be an extension.

[jbms]

Seems reasonable. Note that there are actually 2 lz4 formats, the lower-level "block" format and the higher-level "frame" format. The lz4 command-line tool only supports the frame format. blosc lz4 uses the "block" format. numcodecs lz4 uses the "block" format.

[jakirkham]

Yes this is a good distinction. Thanks Jeremy! 🙏

Wonder whether we are better served by...

1. Having 2 codecs:
   1. lz4-block
   2. lz4-frame
2. One codec lz4 with a config parameter