Compressing Video Files

vynum

Ok, I have noticed from time to time while on usenet, I have downloaded some videos that were compressed at unbelievable compression ratios. Example: I downloaded a video that had an actual size of say 100 megs. It was compressed down to about 18 megs, WOW.

I have just about tried every compression program on the net and I can’t seem to find one that does this. How do these people do this?

I have also tried uping the compression to Maximum, or Ultra etc… I have went to lengths to encode my videos from RAW AVI to just about every other video format in the world, and then compress them with every archival program I could find and I can’t seem to obtain these outragously low file sizes after being archived.

Could someone please tell me how these guys are doing this?

Another example is that I downloaded a 690 CD that was compressed to 280 megs. WoW again!!! This was a DivX video.

MarcFou

I have never seen compression like that before. In fact the opposite. Over the last couple years I have downloaded numerous vid’s that were: RAR, ZIP and 7Zip and the compression ratios were at 0 to 2 percent.

All of these videos were either mpg or wmv. So I am guessing that each file format will have different compression ratios. Things like audio bitrate must be a factor.

Its interesting and I would like to read about other peoples experience with this topic.

TBGBe

@vynum:

Ok, I have noticed from time to time while on usenet, I have downloaded some videos that were compressed at unbelievable compression ratios. Example: I downloaded a video that had an actual size of say 100 megs. It was compressed down to about 18 megs, WOW.

…

Another example is that I downloaded a 690 CD that was compressed to 280 megs. WoW again!!! This was a DivX video.

Well, you have the files, what was the compression format used for the files you downloaded?

spwolf

lossy compression or lossless? I dont see how can something compress an divx file from 690 MB to 280 MB - that would mean that divx format itself is leaving at least 400 MB of extra, unneeded data in the file :-).

on the other hand, lossy formats like divx can always compress better not only because they are specific to one type of files, but because they are lossy - you loose quality for smaller size.

MarcFou

I was just testing WMV and 7Z. I compressed a 163 MB WMV to 7Z (Max) and the compressed file is 164 MB. It actually came out slightly larger in file size.

Using NTFS on XP and the size on disk is larger for 7z as opposed to uncompressed WMV.

vynum

Ok, All of the video files that were compressed had the *.zip extension.

I have been doing alot of research and I have noticed in most of my findings that you can actually “OverZiP” , kinda like “OverClocking” a compression.

WinZip & PKZip both have commandlines. Using the standard compression ratio’s in the GUI is not enough and you will not acheive the most ultimate compression. In addition to this, I found a program called, “ZipMax” found here at: http://www.clrmame.com were you can actually rezip a zip into a better compression using a totally different algorithem. According to the author, most zip archiving programs doesn’t compress to the max, even with max chosen. They breakoff at a certain point.

There is also another method I am just now finding out about, and this seems to be pretty cool but a little bit time consuming but maybe not once you get the hang of it. The program is called “KZIP”. and can be found here: http://www.compression-links.info/Link/1913_KZIP.htm

Kzip is command line only and I have yet found documentation on it and I’m assuming you would use commands of that found for PKzip.

I wonder if anyone has created a special zip program dedicated and geard towards file formats such as mpg,mpeg,rm,DivX,AVI (compressed),wmv…etc…?

I will continue with this endeavor until I find a solution. But I would bet my best bet is to loose the GUI and stick with commandline zipping methods.

EDIT: ADDED

I just found this website with a zip program dedicated to “multimedia” files. I’m going to check it out.

http://debin.net/zzip/

spwolf

None of that has absolutly nothing to do with compressing divx from 700 mb to 280 mb.

Zip/deflate compression will not get you anywhere. In fact, since all these multimedia formats are lossy and already compressed files you will not be able to compress them furthermore by any format, let alone something like zip.

Basic things you need to know:
a. Lossy compression - compression format where you loose quality to gain extra compression strenght (divx, mp3, etc).
c. Lossless compression - compression format where files are left exactly the same. Zip, 7zip, Rar, Ace, etc.

From that, we go to facts:
a. Good lossy compression will by far outcompress lossless compression.
b. You can not improve upon lossy compression by lossless compression afterwards (in this case, ziping an divx).

This is why you can choose quality of MP3 files for example - more quality, higher size, less quality, smaller size. There are lossless multimedia compression formats, however their sizes usually are 3-4x larger than high quality MP3’s so they are seldom used.

spwolf

p.s. “overziping” does not exist. Same sizes are achieved by both command line or GUI, other than possibility of some issues with software in question or completly different software code.

Another thing is that these are PowerArchiver forums - please refrain from mentioning/linking to other compression utilities.

thanks,

davidsplash

www.myinfima.com

i’ve tested the software and better results than anything i’ve seen before

TBGBe

@davidsplash:

www.myinfima.com

i’ve tested the software and better results than anything i’ve seen before

Oops, read this before looking at that - http://www.c10n.info/archives/415

davidsplash

i only tested archiving the files up not extracting them.

we should have a list of bad compression foemats like this as it looks good on the outside but the inside its totally not very good.

spwolf

I am closing this thread. David, you know our policy better than most. Thank you!