This sub-package is in beta testing. Ahead of version 1.0 there may be API changes, but these are expected to be minimal, if any.
This sub-package provides the capability to compress and decompress data using the LZ4 frame specification.
The frame specification is recommended for most applications. A key benefit of using the frame specification (compared to the block specification) is interoperability with other implementations.
These functions are bindings to the LZ4 Frame API functions for compressing data into a single frame, and decompressing a full frame of data.
lz4.frame.
compress
()¶compress(data, compression_level=0, block_size=0, content_checksum=0, block_linked=True, store_size=True, return_bytearray=False)
Compresses data
returning the compressed data as a complete frame.
The returned data includes a header and endmark and so is suitable for writing to a file.
data (str, bytes or buffer-compatible object) – data to compress
block_size (int) –
Sepcifies the maximum blocksize to use. Options:
lz4.frame.BLOCKSIZE_DEFAULT
: the lz4 library default
lz4.frame.BLOCKSIZE_MAX64KB
: 64 kB
lz4.frame.BLOCKSIZE_MAX256KB
: 256 kB
If unspecified, will default to lz4.frame.BLOCKSIZE_DEFAULT
which is currently equal to lz4.frame.BLOCKSIZE_MAX64KB
.
block_linked (bool) – Specifies whether to use block-linked
compression. If True
, the compression ratio is improved,
particularly for small block sizes. Default is True
.
compression_level (int) –
Specifies the level of compression used. Values between 0-16 are valid, with 0 (default) being the lowest compression (0-2 are the same value), and 16 the highest. Values below 0 will enable “fast acceleration”, proportional to the value. Values above 16 will be treated as 16. The following module constants are provided as a convenience:
lz4.frame.COMPRESSIONLEVEL_MIN
: Minimum compression (0, the
default)
lz4.frame.COMPRESSIONLEVEL_MINHC
: Minimum high-compression
mode (3)
lz4.frame.COMPRESSIONLEVEL_MAX
: Maximum compression (16)
content_checksum (bool) – Specifies whether to enable checksumming
of the uncompressed content. If True, a checksum is stored at the
end of the frame, and checked during decompression. Default is
False
.
block_checksum (bool) –
Specifies whether to enable checksumming of
the uncompressed content of each block. If True
a checksum of
the uncompressed data in each block in the frame is stored at
the end of each block. If present, these checksums will be used
to validate the data during decompression. The default is
False
meaning block checksums are not calculated and stored.
This functionality is only supported if the underlying LZ4
library has version >= 1.8.0. Attempting to set this value
to True
with a version of LZ4 < 1.8.0 will cause a
RuntimeError
to be raised.
return_bytearray (bool) – If True
a bytearray
object will be
returned. If False
, a string of bytes is returned. The default
is False
.
store_size (bool) – If True
then the frame will include an 8-byte
header field that is the uncompressed size of data included
within the frame. Default is True
.
Compressed data
bytes or bytearray
lz4.frame.
decompress
(data, return_bytearray=False, return_bytes_read=False)¶Decompresses a frame of data and returns it as a string of bytes.
data (str, bytes or buffer-compatible object) – data to decompress. This should contain a complete LZ4 frame of compressed data.
return_bytearray (bool) – If True
a bytearray object will be
returned. If False
, a string of bytes is returned. The
default is False
.
return_bytes_read (bool) – If True
then the number of bytes read
from data
will also be returned. Default is False
Uncompressed data and optionally the number of bytes read
If the return_bytes_read
argument is True
this function
returns a tuple consisting of:
bytes or bytearray: Uncompressed data
int: Number of bytes consumed from data
bytes/bytearray or tuple
These functions are bindings to the LZ4 Frame API functions allowing piece-wise compression and decompression. Using them requires managing compression and decompression contexts manually. An alternative to using these is to use the context manager classes described in the section below.
lz4.frame.
create_compression_context
()¶Creates a compression context object.
The compression object is required for compression operations.
A compression context
cCtx
lz4.frame.
compress_begin
()¶compress_begin(context, source_size=0, compression_level=0, block_size=0, content_checksum=0, content_size=1, block_mode=0, frame_type=0, auto_flush=1)
Creates a frame header from a compression context.
context (cCtx) – A compression context.
block_size (int) –
Sepcifies the maximum blocksize to use. Options:
lz4.frame.BLOCKSIZE_DEFAULT
: the lz4 library default
lz4.frame.BLOCKSIZE_MAX64KB
: 64 kB
lz4.frame.BLOCKSIZE_MAX256KB
: 256 kB
If unspecified, will default to lz4.frame.BLOCKSIZE_DEFAULT
which is currently equal to lz4.frame.BLOCKSIZE_MAX64KB
.
block_linked (bool) – Specifies whether to use block-linked
compression. If True
, the compression ratio is improved,
particularly for small block sizes. Default is True
.
compression_level (int) –
Specifies the level of compression used. Values between 0-16 are valid, with 0 (default) being the lowest compression (0-2 are the same value), and 16 the highest. Values below 0 will enable “fast acceleration”, proportional to the value. Values above 16 will be treated as 16. The following module constants are provided as a convenience:
lz4.frame.COMPRESSIONLEVEL_MIN
: Minimum compression (0, the
default)
lz4.frame.COMPRESSIONLEVEL_MINHC
: Minimum high-compression
mode (3)
lz4.frame.COMPRESSIONLEVEL_MAX
: Maximum compression (16)
content_checksum (bool) – Specifies whether to enable checksumming
of the uncompressed content. If True, a checksum is stored at the
end of the frame, and checked during decompression. Default is
False
.
block_checksum (bool) –
Specifies whether to enable checksumming of
the uncompressed content of each block. If True
a checksum of
the uncompressed data in each block in the frame is stored at
the end of each block. If present, these checksums will be used
to validate the data during decompression. The default is
False
meaning block checksums are not calculated and stored.
This functionality is only supported if the underlying LZ4
library has version >= 1.8.0. Attempting to set this value
to True
with a version of LZ4 < 1.8.0 will cause a
RuntimeError
to be raised.
return_bytearray (bool) – If True
a bytearray
object will be
returned. If False
, a string of bytes is returned. The default
is False
.
auto_flush (bool) – Enable or disable autoFlush. When autoFlush is disabled
the LZ4 library may buffer data internally until a block is full.
Default is False
(autoFlush disabled).
source_size (int) – This optionally specifies the uncompressed size
of the data to be compressed. If specified, the size will be stored
in the frame header for use during decompression. Default is True
return_bytearray – If True
a bytearray object will be returned.
If False
, a string of bytes is returned. Default is False
.
Frame header.
bytes or bytearray
lz4.frame.
compress_chunk
(context, data)¶Compresses blocks of data and returns the compressed data.
The returned data should be concatenated with the data returned from
lz4.frame.compress_begin
and any subsequent calls to
lz4.frame.compress_chunk
.
context (cCtx) – compression context
data (str, bytes or buffer-compatible object) – data to compress
return_bytearray (bool) – If True
a bytearray object will be
returned. If False
, a string of bytes is returned. The
default is False.
Compressed data.
bytes or bytearray
Notes
If auto flush is disabled (auto_flush=False
when calling
lz4.frame.compress_begin
) this function may buffer and retain
some or all of the compressed data for future calls to
lz4.frame.compress
.
lz4.frame.
compress_flush
(context, end_frame=True, return_bytearray=False)¶Flushes any buffered data held in the compression context.
This flushes any data buffed in the compression context, returning it as
compressed data. The returned data should be appended to the output of
previous calls to lz4.frame.compress_chunk
.
The end_frame
argument specifies whether or not the frame should be
ended. If this is True
and end of frame marker will be appended to
the returned data. In this case, if content_checksum
was True
when calling lz4.frame.compress_begin
, then a checksum of the uncompressed
data will also be included in the returned data.
If the end_frame
argument is True
, the compression context will be
reset and can be re-used.
context (cCtx) – Compression context
end_frame (bool) – If True
the frame will be ended. Default is
True
.
return_bytearray (bool) – If True
a bytearray
object will
be returned. If False
, a bytes
object is returned.
The default is False
.
compressed data.
bytes or bytearray
Notes
If end_frame
is False
but the underlying LZ4 library does not support flushing without ending the frame, a RuntimeError
will be
raised.
lz4.frame.
create_decompression_context
()¶Creates a decompression context object.
A decompression context is needed for decompression operations.
A decompression context
dCtx
lz4.frame.
reset_decompression_context
(context)¶Resets a decompression context object.
This is useful for recovering from an error or for stopping an unfinished decompression and starting a new one with the same context
context (dCtx) – A decompression context
lz4.frame.
decompress_chunk
(context, data, max_length=-1)¶Decompresses part of a frame of compressed data.
The returned uncompressed data should be concatenated with the data
returned from previous calls to lz4.frame.decompress_chunk
context (dCtx) – decompression context
data (str, bytes or buffer-compatible object) – part of a LZ4 frame of compressed data
max_length (int) – if non-negative this specifies the maximum number
of bytes of uncompressed data to return. Default is -1
.
return_bytearray (bool) – If True
a bytearray object will be
returned.If False
, a string of bytes is returned. The
default is False
.
uncompressed data, bytes read, end of frame indicator
This function returns a tuple consisting of:
The uncompressed data as a bytes
or bytearray
object
The number of bytes consumed from input data
as an int
The end of frame indicator as a bool
.
tuple
The end of frame indicator is True
if the end of the compressed
frame has been reached, or False
otherwise
The following function can be used to retrieve information about a compressed frame.
lz4.frame.
get_frame_info
(frame)¶Given a frame of compressed data, returns information about the frame.
frame (str, bytes or buffer-compatible object) – LZ4 compressed frame
Dictionary with keys:
block_size
(int): the maximum size (in bytes) of each block
block_size_id
(int): identifier for maximum block size
content_checksum
(bool): specifies whether the framecontains a checksum of the uncompressed content
content_size
(int): uncompressed size in bytes of
frame content
block_linked
(bool): specifies whether the frame contains
blocks which are independently compressed (False
) or linked
linked (True
)
block_checksum
(bool): specifies whether each block contains a
checksum of its contents
skippable
(bool): whether the block is skippable (True
) or
not (False
)
dict
These classes, which utilize the low level bindings to the Frame API are more convenient to use. They provide context management, and so it is not necessary to manually create and manage compression and decompression contexts.
lz4.frame.
LZ4FrameCompressor
(block_size=0, block_linked=True, compression_level=0, content_checksum=False, block_checksum=False, auto_flush=False, return_bytearray=False)¶Create a LZ4 frame compressor object.
This object can be used to compress data incrementally.
block_size (int) –
Specifies the maximum blocksize to use. Options:
lz4.frame.BLOCKSIZE_DEFAULT
: the lz4 library default
lz4.frame.BLOCKSIZE_MAX64KB
: 64 kB
lz4.frame.BLOCKSIZE_MAX256KB
: 256 kB
If unspecified, will default to lz4.frame.BLOCKSIZE_DEFAULT
which
is equal to lz4.frame.BLOCKSIZE_MAX64KB
.
block_linked (bool) – Specifies whether to use block-linked
compression. If True
, the compression ratio is improved,
especially for small block sizes. If False
the blocks are
compressed independently. The default is True
.
compression_level (int) –
Specifies the level of compression used. Values between 0-16 are valid, with 0 (default) being the lowest compression (0-2 are the same value), and 16 the highest. Values above 16 will be treated as 16. Values between 4-9 are recommended. 0 is the default. The following module constants are provided as a convenience:
lz4.frame.COMPRESSIONLEVEL_MIN
: Minimum compression (0)
lz4.frame.COMPRESSIONLEVEL_MINHC
: Minimum high-compression (3)
lz4.frame.COMPRESSIONLEVEL_MAX
: Maximum compression (16)
content_checksum (bool) – Specifies whether to enable checksumming of
the payload content. If True
, a checksum of the uncompressed
data is stored at the end of the compressed frame which is checked
during decompression. The default is False
.
block_checksum (bool) – Specifies whether to enable checksumming of
the content of each block. If True
a checksum of the
uncompressed data in each block in the frame is stored at the end
of each block. If present, these checksums will be used to
validate the data during decompression. The default is False
,
meaning block checksums are not calculated and stored. This
functionality is only supported if the underlying LZ4 library has
version >= 1.8.0. Attempting to set this value to True
with a
version of LZ4 < 1.8.0 will cause a RuntimeError
to be raised.
auto_flush (bool) – When False
, the LZ4 library may buffer data
until a block is full. When True
no buffering occurs, and
partially full blocks may be returned. The default is False
.
return_bytearray (bool) – When False
a bytes
object is returned
from the calls to methods of this class. When True
a
bytearray
object will be returned. The default is False
.
begin
(source_size=0)¶Begin a compression frame.
The returned data contains frame header information. The data returned
from subsequent calls to compress()
should be concatenated with
this header.
source_size (int) – Optionally specify the total size of the uncompressed data. If specified, will be stored in the compressed frame header as an 8-byte field for later use during decompression. Default is 0 (no size stored).
frame header data
bytes or bytearray
compress
(data)¶Compresses data and returns it.
This compresses data
(a bytes
object), returning a bytes or
bytearray object containing compressed data the input.
If auto_flush
has been set to False
, some of data
may be
buffered internally, for use in later calls to
LZ4FrameCompressor.compress()
and LZ4FrameCompressor.flush()
.
The returned data should be concatenated with the output of any
previous calls to compress()
and a single call to
compress_begin()
.
data (str, bytes or buffer-compatible object) – data to compress
compressed data
bytes or bytearray
flush
()¶Finish the compression process.
This returns a bytes
or bytearray
object containing any data
stored in the compressor’s internal buffers and a frame footer.
The LZ4FrameCompressor instance may be re-used after this method has been called to create a new frame of compressed data.
compressed data and frame footer.
bytes or bytearray
reset
()¶Reset the LZ4FrameCompressor
instance.
This allows the LZ4FrameCompression
instance to be re-used after an
error.
lz4.frame.
LZ4FrameDecompressor
(return_bytearray=False)¶Create a LZ4 frame decompressor object.
This can be used to decompress data incrementally.
For a more convenient way of decompressing an entire compressed frame at
once, see lz4.frame.decompress()
.
return_bytearray (bool) – When False
a bytes object is returned from
the calls to methods of this class. When True
a bytearray
object will be returned. The default is False
.
eof
¶True
if the end-of-stream marker has been reached.
False
otherwise.
bool
unused_data
¶Data found after the end of the compressed stream.
Before the end of the frame is reached, this will be b''
.
bytes
needs_input
¶False
if the decompress()
method can
provide more decompressed data before requiring new uncompressed
input. True
otherwise.
bool
decompress
(data, max_length=-1)¶Decompresses part or all of an LZ4 frame of compressed data.
The returned data should be concatenated with the output of any
previous calls to decompress()
.
If max_length
is non-negative, returns at most max_length
bytes
of decompressed data. If this limit is reached and further output can
be produced, the needs_input
attribute will be set to False
. In
this case, the next call to decompress()
may provide data as
b''
to obtain more of the output. In all cases, any unconsumed data
from previous calls will be prepended to the input data.
If all of the input data
was decompressed and returned (either
because this was less than max_length
bytes, or because
max_length
was negative), the needs_input
attribute will be set
to True
.
If an end of frame marker is encountered in the data during
decompression, decompression will stop at the end of the frame, and any
data after the end of frame is available from the unused_data
attribute. In this case, the LZ4FrameDecompressor
instance is reset
and can be used for further decompression.
data (str, bytes or buffer-compatible object) – compressed data to decompress
max_length (int) – If this is non-negative, this method returns at
most max_length
bytes of decompressed data.
Uncompressed data
bytes
reset
()¶Reset the decompressor state.
This is useful after an error occurs, allowing re-use of the instance.
These provide capability for reading and writing of files using LZ4 compressed frames. These are designed to be drop in replacements for the LZMA, BZ2 and Gzip equivalent functionalities in the Python standard library.
lz4.frame.
open
(filename, mode='rb', encoding=None, errors=None, newline=None, block_size=0, block_linked=True, compression_level=0, content_checksum=False, block_checksum=False, auto_flush=False, return_bytearray=False, source_size=0)¶Open an LZ4Frame-compressed file in binary or text mode.
filename
can be either an actual file name (given as a str, bytes, or
PathLike object), in which case the named file is opened, or it can be an
existing file object to read from or write to.
The mode
argument can be 'r'
, 'rb'
(default), 'w'
,
'wb'
, 'x'
, 'xb'
, 'a'
, or 'ab'
for binary mode, or
'rt'
, 'wt'
, 'xt'
, or 'at'
for text mode.
For binary mode, this function is equivalent to the LZ4FrameFile
constructor: LZ4FrameFile(filename, mode, ...)
.
For text mode, an LZ4FrameFile
object is created, and wrapped in an
io.TextIOWrapper
instance with the specified encoding, error handling
behavior, and line ending(s).
filename (str, bytes, os.PathLike) – file name or file object to open
mode (str) – mode for opening the file
encoding (str) – the name of the encoding that will be used for
encoding/deconging the stream. It defaults to
locale.getpreferredencoding(False)
. See io.TextIOWrapper
for further details.
errors (str) – specifies how encoding and decoding errors are to be
handled. See io.TextIOWrapper
for further details.
newline (str) – controls how line endings are handled. See
io.TextIOWrapper
for further details.
return_bytearray (bool) – When False
a bytes object is returned
from the calls to methods of this class. When True
a bytearray
object will be returned. The default is False
.
source_size (int) – Optionally specify the total size of the uncompressed data. If specified, will be stored in the compressed frame header as an 8-byte field for later use during decompression. Default is 0 (no size stored). Only used for writing compressed files.
block_size (int) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
block_linked (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
compression_level (int) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
content_checksum (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
block_checksum (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
auto_flush (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
lz4.frame.
LZ4FrameFile
(filename=None, mode='r', block_size=0, block_linked=True, compression_level=0, content_checksum=False, block_checksum=False, auto_flush=False, return_bytearray=False, source_size=0)¶A file object providing transparent LZ4F (de)compression.
An LZ4FFile can act as a wrapper for an existing file object, or refer directly to a named file on disk.
Note that LZ4FFile provides a binary file interface - data read is returned as bytes, and data to be written must be given as bytes.
When opening a file for writing, the settings used by the compressor can be
specified. The underlying compressor object is
lz4.frame.LZ4FrameCompressor
. See the docstrings for that class for
details on compression options.
filename (str, bytes, PathLike, file object) – can be either an actual file name (given as a str, bytes, or PathLike object), in which case the named file is opened, or it can be an existing file object to read from or write to.
mode (str) – mode can be 'r'
for reading (default), 'w'
for
(over)writing, 'x'
for creating exclusively, or 'a'
for appending. These can equivalently be given as 'rb'
,
'wb'
, 'xb'
and 'ab'
respectively.
return_bytearray (bool) – When False
a bytes object is returned from
the calls to methods of this class. When True
a bytearray
object will be returned. The default is False
.
source_size (int) – Optionally specify the total size of the
uncompressed data. If specified, will be stored in the compressed
frame header as an 8-byte field for later use during decompression.
Default is 0
(no size stored). Only used for writing
compressed files.
block_size (int) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
block_linked (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
compression_level (int) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
content_checksum (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
block_checksum (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
auto_flush (bool) – Compressor setting. See
lz4.frame.LZ4FrameCompressor
.
close
()¶Flush and close the file.
May be called more than once without error. Once the file is closed, any other operation on it will raise a ValueError.
closed
¶Returns True
if this file is closed.
True
if the file is closed, False
otherwise.
bool
fileno
()¶Return the file descriptor for the underlying file.
file descriptor for file.
file object
peek
(size=-1)¶Return buffered data without advancing the file position.
Always returns at least one byte of data, unless at EOF. The exact number of bytes returned is unspecified.
uncompressed data
bytes
read
(size=-1)¶Read up to size
uncompressed bytes from the file.
If size
is negative or omitted, read until EOF
is reached.
Returns b''
if the file is already at EOF
.
size (int) – If non-negative, specifies the maximum number of uncompressed bytes to return.
uncompressed data
bytes
read1
(size=-1)¶Read up to size
uncompressed bytes.
This method tries to avoid making multiple reads from the underlying stream.
This method reads up to a buffer’s worth of data if size
is
negative.
Returns b''
if the file is at EOF.
size (int) – If non-negative, specifies the maximum number of uncompressed bytes to return.
uncompressed data
bytes
readable
()¶Return whether the file was opened for reading.
True
if the file was opened for reading, False
otherwise.
bool
readline
(size=-1)¶Read a line of uncompressed bytes from the file.
The terminating newline (if present) is retained. If size is non-negative, no more than size bytes will be read (in which case the line may be incomplete). Returns b’’ if already at EOF.
size (int) – If non-negative, specifies the maximum number of uncompressed bytes to return.
uncompressed data
bytes
seek
(offset, whence=0)¶Change the file position.
The new position is specified by offset
, relative to the position
indicated by whence
. Possible values for whence
are:
io.SEEK_SET
or 0: start of stream (default): offset must not be
negative
io.SEEK_CUR
or 1: current stream position
io.SEEK_END
or 2: end of stream; offset must not be positive
Returns the new file position.
Note that seeking is emulated, so depending on the parameters, this operation may be extremely slow.
offset (int) – new position in the file
whence (int) – position with which offset
is measured. Allowed
values are 0, 1, 2. The default is 0 (start of stream).
new file position
int
seekable
()¶Return whether the file supports seeking.
True
if the file supports seeking, False
otherwise.
bool
tell
()¶Return the current file position.
None –
file position
int
writable
()¶Return whether the file was opened for writing.
True
if the file was opened for writing, False
otherwise.
bool
write
(data)¶Write a bytes object to the file.
Returns the number of uncompressed bytes written, which is always
len(data)
. Note that due to buffering, the file on disk may not
reflect the data written until close() is called.
data (bytes) – uncompressed data to compress and write to the file
the number of uncompressed bytes written to the file
int
A number of module attributes are defined for convenience. These are detailed below.
The following module attributes can be used when setting the
compression_level
argument.
lz4.frame.
COMPRESSIONLEVEL_MIN
¶Specifier for the minimum compression level.
Specifying compression_level=lz4.frame.COMPRESSIONLEVEL_MIN
will
instruct the LZ4 library to use a compression level of 0
lz4.frame.
COMPRESSIONLEVEL_MINHC
¶Specifier for the minimum compression level for high compression mode.
Specifying compression_level=lz4.frame.COMPRESSIONLEVEL_MINHC
will
instruct the LZ4 library to use a compression level of 3, the minimum for the
high compression mode.
lz4.frame.
COMPRESSIONLEVEL_MAX
¶Specifier for the maximum compression level.
Specifying compression_level=lz4.frame.COMPRESSIONLEVEL_MAX
will
instruct the LZ4 library to use a compression level of 16, the highest
compression level available.
The following attributes can be used when setting the block_size
argument.
lz4.frame.
BLOCKSIZE_DEFAULT
¶Specifier for the default block size.
Specifying block_size=lz4.frame.BLOCKSIZE_DEFAULT
will instruct the LZ4
library to use the default maximum blocksize. This is currently equivalent to
lz4.frame.BLOCKSIZE_MAX64KB
lz4.frame.
BLOCKSIZE_MAX64KB
¶Specifier for a maximum block size of 64 kB.
Specifying block_size=lz4.frame.BLOCKSIZE_MAX64KB
will instruct the LZ4
library to create blocks containing a maximum of 64 kB of uncompressed data.
lz4.frame.
BLOCKSIZE_MAX256KB
¶Specifier for a maximum block size of 256 kB.
Specifying block_size=lz4.frame.BLOCKSIZE_MAX256KB
will instruct the LZ4
library to create blocks containing a maximum of 256 kB of uncompressed data.
lz4.frame.
BLOCKSIZE_MAX1MB
¶Specifier for a maximum block size of 1 MB.
Specifying block_size=lz4.frame.BLOCKSIZE_MAX1MB
will instruct the LZ4
library to create blocks containing a maximum of 1 MB of uncompressed data.
lz4.frame.
BLOCKSIZE_MAX4MB
¶Specifier for a maximum block size of 4 MB.
Specifying block_size=lz4.frame.BLOCKSIZE_MAX4MB
will instruct the LZ4
library to create blocks containing a maximum of 4 MB of uncompressed data.