I need to compress a file of 15 Gb
Every day I make a export of our database. This export is 15 Gb big.
Then I copy this file to tape.
To make the file smaller I want to compress it, before I copy it to
Unfortunaly with the compress tool I have I get an error because the
file is far too big. I use winzip.
I work with a windows platform
My question: does anyone have good suggestions for my problem?
>Every day I make a export of our database. This export is 15 Gb big.
>Then I copy this file to tape.
>To make the file smaller I want to compress it, before I copy it to
>Unfortunaly with the c...Compressing compressed files?
I have a really crazy idea:
Supposing you took a compressed file (any format) and pass it to a
bijective decompressor,In principle the data should become less
random. After that you can recompress the data with a superior
My reasoning is as follows:
The set of input data for most general purpose compression algorithms
tends to overlap. Within a certain margin , the set of compressed
files overlaps too.
I tried this out on a couple of files with David Scott's BICOM but I
didn't get any positive result.
My idea was that since PPMII does 40 - 50 % better than ZIP and there
...Further compress a already compressed file
My question is, can a compressed file be further compressed by
the same compression algorithm or other compresssion
algorithm? Why or Why not?
My experimental result is. Yes, it can be further compressed by a
considerably amount. (sometimes 50%)
Is that theoratically possible? This is against the impression I used
to have. Can some one kindly answer my question or give me some
- detailed description -------------------------------------
compression library : LZO
my data set : binary data.
I have a program that uses lzo library to com...Re: Re. Error in reading compressed file
Using a pipe to run winzip can be used, I think, for uncompressing any kind
of file -- but definitely a csv file (although yours has that extension is
not really a comma separated file as I recall it is separated with semi-
Take a look at the example at:
Let us know if you still need to know how to re-write any of the files
(i.e., deleting an extra line).
On Fri, 8 Jan 2010 12:02:52 +0100, Elvira Sojli <ESojli@RSM.NL> wrote:
>Dear Art and Tom,
>Thanks again for the quick repl...For Compression Gurus: Need help on compressing intervals
I have a set of intervals, each of equal size that can overlap.
Lets assume we are working on the integer line. So we have,
(a_1, a_1 + k) (a_2, a_2 + k) ... (a_n, a_n + k)
From each interval I want to pick up one number so that the resulting
numbers can be compressed very well (Say using Huffman coding or
Arithmetic coding). (This is an optimization problem in some sense,
what should be picked up so that the resulting compression is best).
Can someone tell me how to solve this problem, or give me
pointers to work on this topic? If you are a coder, woul...Image compression code to compress JPEG file
currently a scanned document in JPEG format is occupying around 350KB
space. I need a compression code which reduces disk space from 350KB
to around 50KB. code may be in VB6 (preferrably). please help me out.
its pretty urgent.
> currently a scanned document in JPEG format is occupying around 350KB
> space. I need a compression code which reduces disk space from 350KB
> to around 50KB. code may be in VB6 (preferrably). please help me out.
> its pretty urgent.
If this document is a black and white "line art" type writer document,
then I afraid you'...first time successfull? compressing compressed files
The current version of Adobe Reader 6 installation, which is around 9
MB, installs in two phases. First is performed by Netopsys's FEAD
code, which "recomposes" the installation files to the state we're
used to (executables+big cab)
Resulting codes and cab together are more than twice bigger than the
installation single EXE (*1)
I analyzed the CABs and found that the biggest EXE appears twice,
removed it and repacked it. If I'd pack to the same CAB even all the
remaining executables, everything packed together (CAB files us...Compression Algorithm and code for text and audio compression needed
Can any one help me out with huffmans adaptive code for text
compression code for my project. and also i need to know audio
compression algorithms can i use huffmans and lzw or lzs for it and if
yes where can i find the code for it.
> Hi !
> Can any one help me out with huffmans adaptive code for text
> compression code for my project. and also i need to know audio
> compression algorithms can i use huffmans and lzw or lzs for it and if
> yes where can i find the code for it.
Audio compression is generally lossy. You can listen to some examples of
compresse...Re: Compressing backup file
On 5 May 2006 at 11:39, Kevin Handy wrote:
> I am looking at creating a backup file, then compressing
> it, copying it to a PC, and burning it to a CD.
Why not use DECnet to back the machine across DECnet to a Linux box?
ZIP the saveset there, and burn...
DECnet for Linux is at:
Works like a champ. And the price is right!
Quayle Consulting Inc.
Stanley F. Quayle, P.E. N8SQ Toll free: 1-888-I-LUV-VAX
8572 North Spring Ct., Pickerington, OH 43147 USA
"...Re: Compressing files and FTP
"Tony Summers" wrote in part:
>Anybody any thoughts on the best way to compress a
>variable record length file from a Cobol program
>prior to transmitting it via FTP ?
Sure, but there are plenty of questions. What is the target platform? That
will likely constrain your list of choices. You will need a compression
scheme available on both sides of this ftp. LZW is available on various
platforms; I've used it on NT. STD may be a good choice if the target is
another 3000. You go on to mention bytestream, which makes me suspect that
you are going to someone else'...compress utility != Compress::Zlib::compress() on linux and Windows
For some reason when the compress utility is used to
create a .Z file, the result is not recognized by the Compress::Zlib
uncompress() function (on either Linux
And it turns out that Compress::Zlib::compress() produces
a _different_ .Z file. Editing the two seems to show that
the contents are the same after a certain point and thus
the headers differ. DOH!
I am running with perl v5.8.6, in which Compress::Zlib
v1.33 is bundled. (v1.34 was released in 2005-01; but I
doubt if 1.33 is drastically out of date.)
Can anyone shed some light on this? If so, you'll be doing
better ...To Compress or Not To Compress -- That is the Question !
I'm running a website (I have three sites on my older Dell -- Pentium 4
with 2GB of Memory and a 350Gig Harddrive) with an xHarbour .exe as the CGI
If I have many simultaneous clients, is there a significant benefit or
penalty to compressing the .exe ?
Currently, one of the compressed executables is 486,400 bytes.
Uncompressed, it is 1,076,224 bytes.
I welcome your opinions.
In case of your setup IMHO the compressed .exe has no advantages, the
decompressing operation ( aka UnZip )
- eats the serv...yes, it is possible to compress previously compressed files/messages,
I am the person that scares those "ostriches" with their head in the
sand, those 'scientists' (here I am using that term loosely,) that
assert that compression of random data is impossible.
That's not to say that I have handled things in a most optimum manner
either -- I've made lot's of mistakes too.
But as to the question itself, "is it possible to compress previously
compressed files/messages," and then, using the smaller output file,
to compress that file, so that the original client file, perhaps many
GB's in size, can be represented in only, ...compressing compressed video
Is it possible to noticeably compress already compressed video (DivX/MPEG)
even futher using a loseless compression program? Which programs offer the
highest compression radios in this case?
> Is it possible to noticeably compress already compressed video (DivX/MPEG)
> even futher using a loseless compression program?
Yes, but not by much if at all. The most lossless compression I have
seen of an .AVI occured because the PCM audio was uncompressed. The
only .AVIs you'll see major compression occur is when there is so much
redundant information in a frame or ...Re: Video Compression Players Should "Compress" Hype
I continue watch Qbit, and as expected, they are thrown in with the
People from Pixe have updated their website.
Should we expect samples soon?
> I continue watch Qbit, and as expected, they are thrown in with the
> 'hype' gang.
Looks like the Washington DC Technology Council thinks Qbit is real!
* Qbit, LLC -- Provides enabling technologies for pa...Re: Compressing files and FTP #6
Tony Summers wrote:
> ... but I was hoping that there was some way
>of directly invoking the compressing from our Cobol programs - i.e. some
>sort of system instrinsic call I could make.
The compression routines of zip/unzip (google: InfoZIP) are also
available as library (www.zlib.org) that also builds on MPE/iX. Not
sure, however, if the API is convenient for calling from COBOL or
if a command file or script is easier to use.
* To join/leave the list, search archives, change list settings, *
* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
...Re: Reading compressed unix files
First off I am assuming you are on a linux system reading a tar file made
on a linux system and the files stored in the tar archives are some kind of
flat text files. None of this may hold but it may help you understand where
I am coming from with the rest of this post. Hopefully it will at the very
least help get you moving in the right direction.
I would first recommend that you first check out the tar doc at
As to reading multiple files I think you can find a solution by using some
code like Richard posted to retriev...Re: Compressing backup file #5
From: "Tom Linden" <firstname.lastname@example.org>
> Well, when I tried it on a large file it ground away for quite some time
> and then
> emitted an error message that the uncompressed file was larger than 4GB.
First, as usual, it would be helpful to see the command used, data on
the file(s) being processed, and the actual error message emitted.
> why wouldn't it first ascertain the file size before attempting to
Possibly because when it was written, there were no files larger than
the C RTL functions then available could handle. Supp...Re: Compressing files and FTP #3
Lars Appel wrote:
> An alternative to zip might be using tar with -cvzf options. This
> combines tar and compress in one step. And tar (unlike zip) comes
> with MPE/iX FOS. If your ftp is between two MPE systems, this will
> also attempt to preserve MPE file attributes, I believe.
does mpe tar have the same 4gb limitation as on unix systems?
Donna Garverick Sr. System Programmer
Come, my friends, 'Tis not too late to seek a newer world.
Tho' much is taken, much abides; and tho'
We are not now that s...Re: Compressing wmv/avi files
I don't see that you got a response to this. I don't know of a way in =
SAS, but in Windows XP you can right-click on the file and then do a =
send-to compressed zipped folder. To uncompress it click on the =
compressed folder and do file-extract all. =20
----- Original Message -----=20
From: Narasimha Rao M=20
Sent: Friday, September 28, 2007 1:29 PM
Subject: Compressing wmv/avi files
I am currently trying to compress size of media files. Is there any =
reduce size of a .wmv or .avi file from sa...Re: Compressing files and FTP #5
Donna Garverick wrote:
>does mpe tar have the same 4gb limitation as on unix systems?
No, I guess it doesn't. It cannot even get beyond 2 GB ;-)
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* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
...Re: Compressing backup file #4
----- Original Message -----
From: "Hoff Hoffman" <email@example.com>
Sent: Thursday, May 11, 2006 9:36 PM
Subject: Re: Compressing backup file
> Steven M. Schweda wrote:
>> From: "Tom Linden" <firstname.lastname@example.org>
>>> Is DVD supported as output device for backup on 8.3?
>> Directly? I doubt it.
> The CD-R/RW and DVD+R/RW recording capabilities that are present
> within V8.3 require the generation of a master, or the use of a file
> containing a disk image. The ...Re: Compressing files and FTP #4
Thanks Greg for the useful comments.
The target platform is initially another HP3K, but eventually will
mostly likely become an HP-UX server once we start to migrate our systems.
Yes, FTP is called from our cobol programs, but all
we've done is package up a call to the HP3K's FTP client inside
a general subroutine which creates the necessary scripts for us. I could
do the same for the compression routine - calling whatever I needed via
a subroutine of our creation, but I was hoping that there was some way
of directly invoking the compressing from our Cobol programs - i.e....Re. Error in reading compressed file
Dear Art and Tom,
Thanks again for the quick replies. I have spent the morning going
through different things, trying to locate the problem more
1. So like Art I created a dummy file using the first lines of my
problematic csv's and zipped with WINZIP (this is essential for saszipam
to work). I can unzip and read the file without a problem. The problem
reoccurs when the file is very long. The SAS error messages are below,
for the file that works and the one that doesn't.=20
2. When I unzip the file and run the code, I can read the CSV witho...