[ANSWERED] Inefficient ISO compression?

Hey winterstorm2050!

Just for fun, I tried to open my untouched ISO (8.1 Enterprise x64 german) in WinReducer 8.1 v1.00 (RC1), then WITHOUT changing anything create another ISO. In theory, the newly created ISO should be almost identical to the original one, but in reality it is nearly 80 MB bigger!

I then compared the two ISOs, here are the differences (for the sake of simplicity, let's call them "untouched.iso" and "winreducer.iso"):

1) ISO files:

 *) untouched.iso : 3.911.393.280 Bytes
 *) winreducer.iso : 3.993.006.080 Bytes -> 81.612.800 Bytes = 77,83 MB bigger!

2) ISO extraction:

 *) untouched.iso : 3.995.145.221 Bytes
 *) winreducer.iso : 3.978.967.513 Bytes -> 16.177.708 Bytes = 15,43 MB smaller!

3) Detailed File comparison of the extracted folders:

 *) winreducer.iso\WinReducer81.wccf : 71.440 Bytes = 69,77 KB
 *) untouched.iso\sources\boot.wim : 271.252.394 Bytes
 *) winreducer.iso\sources\boot.wim : 259.614.052 Bytes -> 11.638.342 Bytes = 11,10 MB smaller!
 *) untouched.iso\sources\install.wim : 3.252.099.400 Bytes
 *) winreducer.iso\sources\install.wim : 3.247.488.594 Bytes -> 4.610.806 Bytes = 4,40 MB smaller!

So while the compression in the .wim files seems to be even better than the original one (15,43 MB saved in total), this advantage is lost in the ISO compression (77,83 MB more).

Interestingly, while the untouched.iso is slightly smaller than its extracted contents (aka compression), the winreducer.iso is nearly 14 MB BIGGER than its extracted contents! How did this happen?

Just wanted to let you know

Hey mannik77,

Really interesting thread, thank you for this. I will try to have a look on this increasing size during ISO creation !

 

By the way, if I may ask: If I do it the way I described, what does WinReducer actually do with the image? Three things I know for sure:

1) Adding the file "WinReducer81.wccf" to the root directory of the ISO (BTW: It would be great to have an option to disable this )
2) Reducing the boot.wim in some way (?)
3) Reducing the install.wim in some way (?)

Since I prefer my ISO as clean as possible, I would really love to know what WinReducer does with the ".wim" files, and why they are smaller than the original ones   Honestly, I have no idea how to compare the original ".wim"s with the reduced ones, so I thought just asking the author of the program might be easier

Concerning the ISO size problem: I think maybe the command line parameters of OSCDIMG.EXE might be the cause. The way I see it, there are quite a few optimization options available (-o, -oc, -oi, -ocs, -ois). Perhaps one of them proves to be the best one

i think winreducer uses with imagex.exe the parameters "/compress maximum" while unmounting/captureing

and the normal windows wim image got "/compress fast" or "none"

i think it depends on the Oscdimg.exe commands used.
I just used the bios+Uefi one and it made the image go from 4.12 GB to 4.03GB just through compression compared to a command i was using previously
http://forums.mydigitallife.info/threads/51982-How-To-Using-Oscdimg-exe-for-Building-W7-x-W8-x-WinPE-Bootable-DVD-ISO-Image


Ps: I also think by default the iso should be bios+Uefi, and on the winreducer iso creation screen, and have two tick boxes
Bios Only & UEFI Only user can check one or the other if they want those options.