Dear Fox,
There is absolutely no reason that the Tcl-builtin function zlib
returns different results in tclsh and naviserver. I could
not reproduce different results in these two environments,
also when modifying the compression level (see comments below).
I slightly modified your script my making sure that the resulting
file is binary and contains no extra newline at the end.
While correcting this, i noticed that the size of the file
differed in the range as you reported when writing the
file binary or not (as in your case). So, my suspicion
is that you compared the result of binary result writing
in tclsh with non-binary result writing in NaviServer.
Can you report the different results with the modified script?
-g
==================================
set inFile "/tmp/myImage.png"
set outFile "/tmp/myImage.png.ixz"
set myFile [open $inFile RDONLY]
fconfigure $myFile -translation binary
set content [read $myFile]
close $myFile
set binData [encoding convertto utf-8 $content]
set hexData [binary encode hex [encoding convertto utf-8 $content]]
# level 0 => 2.56 MB
# level 6 => 1.13 MB
# level not specified 1.13 MB
# level 9 => 1.11 MB
set fp [open $outFile w]
fconfigure $fp -translation binary
puts -nonewline $fp [zlib compress $hexData]
close $fp
puts stderr [subst {
/tmp/myImage.png: [clock format [file mtime /tmp/myImage.png]] [file
size /tmp/myImage.png]
/tmp/myImage.png.ixz [clock format [file mtime /tmp/myImage.png.ixz]] [file
size /tmp/myImage.png.ixz]
}]
On 10.05.20 15:59, D.Fox wrote:
Hi, I am trying to compress a image (.png) using hexadecimal and ZLIB.
When running the below code within naviserver the created file is
larger then if I run standalone shell.
The sample code is as follows:
#########
set file "/bench/myImage.png"
set filePath "/bench/"
set myFile [open $file RDONLY]
fconfigure $ myFile -translation binary
set content [read $myFile]
set binData [encoding convertto utf-8 $content]
set hexData [binary encode hex [encoding convertto utf-8 $content]]
close $myFile
set fp [open "$filePath/myCompressedHexBlobFile.ixz" w]
puts $fp [zlib compress $hexData]
close $fp
#########
Outputs:
846K - myImage.png
1.7M - myCompressedHexBlobFile.ixz - Executed within Naviserver
1.1M - myCompressedHexBlobFile.ixz - Executed from shell with TCLSH
#########
Is Navi using a different zlib compression level, why is this happening?
If I set the compression level to nine, the created file is still at
1.7mb. This is kind of a game changer, even if I source the
compression script the file size is still larger then if I run it via
terminal.
Thanks
Fox
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