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 ...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doubt if 1.33 is drastically out of date.)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 ...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
...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...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...compressing an already compressed archive
why it is said that compressing an already compressed archive will
not have much benefit , independent of the algorithm being used ?
annalissa <email@example.com> wrote:
> why it is said that compressing an already compressed archive will
> not have much benefit , independent of the algorithm being used ?
Well, it isn't true in general, but is usually for reasonable
Some time ago I was working on a program to generate PDFs
of scanned images. First I did the run-length compression, as
that was pretty easy. Then I added LZW, but didn't...Compress an already compressed Jpeg
We are trialing some software that very basically allows your average Joe
with the correct client software installed send an image file via the
internet to a server running the server side of this software. While this is
already very easy to do with a bit of HTML code and asp/php e.t.c to receive
and manipulate the file. This software claims to compress the image before
it is sent and then decompress the server end with no loss using file
compression rather than further image compression. What's more it claims it
compresses them up to 80% compression before transfer!
While I can believe t...Compression Qs from a Compression Newbie
When compressing something, what are all the factors used to evaluate
how helpful / good the compression method is, in general, and in a
I am interested in finding ways to compress combinations of data that
include time / date information about the functioning of an operating
system, video data collected under the same o.s., and parts of the o.s.
software itself. Does anyone have any experience with anything like
this and would anyone have any helpful pointers? I am hoping that
patterns or redundancies in the data can be used to compress it.
Any helfup input appreciated,
...How compress a string into a compressed string?
I use VC++.NET 2003.
I want to compress following text string.
I store following text in std::string.
did somebody experienced that behaviour?
(there are no concurrent sessions)
mmm@APPL> select count(*) from t_noc;
mmm@APPL> alter table t_noc move compress;
Tabelle wurde ge�ndert.
mmm@APPL> select count(*) from t_noc;
I could reproduce this on 22.214.171.124 as well 126.96.36.199 on linux, i'd searched
Metalink on this issue, but found nothing similar. I'll open an iTAR
tomorrow, but, maybe, its a known bug, so any expirience will be
appreciated. The only thing i can suspict at the moment - there are 2
colu...AAC compression chips? Other compression chips?
I'm looking for inexpensive hardware solution (chips) to encode groups
of 6 channel 44/48k signals into streams of preferably AAC. Or WMA or
MP3 or AC-3 if it is simpler.
The idea is that signal is input as regular 48k/24bit pcm, than the
user can select compression DR (eg 64kbps for 12 channels or 128kpbs for
6 channels) and the circuit will spit out serial encoded data in a RS422
like format to be tranmitted through a radio link.
At the receiving end a decoder would reverse the above, I can see quite
a few decoder chips.
Is there an audio encoder chip out there? (other t...Index compression vs. table compression
I run Oracle 188.8.131.52 on a RedHat AS 2.1 box with 8 Xeon CPUs.
There is a clear mismatch between the overwhelming computer power and
the poor disks attached. I am contemplating to setup a tablespace with
compression and a blocksize of 16K (queries are of Data Warehouse
type), and the corresponding 16k db cache (there is enough RAM), in
order to take better advantage of this situation (the standard
blocksize is 8K).
That is quite simple to do. A simple "alter table xxx move compress
tablespace DWH_16C" should do it. But with indexes, there is a
difference I don't quite unde...Determine compression method from compressed data
Maybe one of you recognizes some characteristic bits in the stream
described below. My goal is to find a way to compress a different stream so
that the same given decoder will be able to decompress it, but I haven't
yet been able to determine the compression method nor its parameters.
There is no header (no gzip,arj,...). Data is stored in contiguous chunks;
each prefixed with one big-endian 16-bit word specifying the expected
length (in bytes) of the chunk when uncompressed, and a second word
specifying the number of bytes following in the compressed chunk.
The uncompressed length...vmzcore.NN not in compressed format but compressed?
I'm looking for a 60-ft bungee cord and a 40-ft bridge....
I'm trying to analyze a crash dump. Here is the current issue:
# ls *.28
crash-data.28 vmunix.28 vmzcore.28
# file *.28
crash-data.28: ascii text
vmunix.28: COFF format alpha executable or object module not
stripped - version 3.13-14
vmzcore.28: compressed memory image(dump) file
# ln -s vmzcore.28 vmzcore.28.Z
# zcat vmzcore.28.Z | dd of=/tmp/vmcore.28 conv=sparse
vmzcore.28.Z: not in compressed format
0+0 records in
0+0 records out
So the file ...