Documentation of the AdvanceCOMP advdef utility.
1
Synopsis
advdef [-z, --recompress] [-0, --shrink-store]
[-1, --shrink-fast] [-2, --shrink-normal] [-3, --shrink-extra]
[-4, --shrink-insane] [-i, --iter N]
[-f, --force] [-q, --quiet]
[-h, --help] [-V, --version] FILES...
2
Description
The main purpose of this utility is to recompress the
data present in the .png, .mng, .gz, .tgz and .svgz
files.
The internal structure of the files isn't changed.
Only the compressed data is modified.
3
Options
-z, --recompress FILES...
|
Recompress the specified files. If the -1, -2, -3, -4
options are specified it's used the smallest file
choice from the previous compressed data and the
new compression. If the -0 option is specified the
file is always rewritten without any compression.
|
-0, --shrink-store
|
Disable the compression. The file is
only stored and not compressed. The file is always
rewritten also if it's bigger.
|
-1, --shrink-fast
|
Set the compression level to "fast" using the zlib
compressor.
|
-2, --shrink-normal
|
Set the compression level to "normal" using the libdeflate
compressor.
This is the default level of compression.
|
-3, --shrink-extra
|
Set the compression level to "extra" using the 7z
compressor.
You can define the compressor iterations with
the -i, --iter option.
|
-4, --shrink-insane
|
Set the compression level to "insane" using the zopfli
compressor.
You can define the compressor iterations with
the -i, --iter option.
|
-i, --iter N
|
Define an additional numer of iterations for the 7z and zopfli
compressors for modes -3 and -4.
More iterations usually give a better compression, but may
require a lot more time.
Try for example with 10, 15, 20, and so on.
|
-f, --force
|
Force the use of the new file also if it's bigger.
|
4
Limitations
The advdef program cannot be used to recompress huge files
because it needs to allocate memory for both the complete
compressed and uncompressed data.