Miscellaneous APIs¶

Frame Inspection¶

Data emitted from zstd compression is encapsulated in a frame. This frame begins with a 4 byte magic number header followed by 2 to 14 bytes describing the frame in more detail. For more info, see https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md.

The following module constants/attributes are exposed:

ZSTD_VERSION

This module attribute exposes a 3-tuple of the Zstandard version. e.g. (1, 0, 0)

MAX_COMPRESSION_LEVEL

Integer max compression level accepted by compression functions

COMPRESSION_RECOMMENDED_INPUT_SIZE

Recommended chunk size to feed to compressor functions

COMPRESSION_RECOMMENDED_OUTPUT_SIZE

Recommended chunk size for compression output

DECOMPRESSION_RECOMMENDED_INPUT_SIZE

Recommended chunk size to feed into decompresor functions

DECOMPRESSION_RECOMMENDED_OUTPUT_SIZE

Recommended chunk size for decompression output

FRAME_HEADER

bytes containing header of the Zstandard frame

MAGIC_NUMBER

Frame header as an integer

FLUSH_BLOCK

Flushing behavior that denotes to flush a zstd block. A decompressor will be able to decode all data fed into the compressor so far.

FLUSH_FRAME

Flushing behavior that denotes to end a zstd frame. Any new data fed to the compressor will start a new frame.

CONTENTSIZE_UNKNOWN

Value for content size when the content size is unknown.

CONTENTSIZE_ERROR

Value for content size when content size couldn’t be determined.

WINDOWLOG_MIN