I'm sorry, but my bros says that not remember what parameters used to make a so high compression.
I downloaded latest version of 7zip in the afternoon and made some attempts, but don't have enough CPU power to complete work. I tried to use the most compression possible, but my computer locks with CPU 100% and over 1,6 GB memory used (according task manager).
I was forced to close application with task manager to be able to use my computer again.
I tried to compress a 160 MB mpeg file at maximum possible, and after 1 hour
I obtained a 66 MB temporary file; 7zip says that work in progress was 46% when I closed application with task manager. This is not a so high compression.
However I know that a such high compresson is possible because I've seen these compressed files, and I know that decompression require only a couple of minutes. My bros said that it was necessary about an hour to him to compress a file with a pentium 4 and 2 GB of memory, but not remember other because he don't use anymore 7zip. I know that is difficult to trust that an already compresse file can be squeezed so many, but I repeat that I've seen these files.
I'm very sorry to not be able to give more informations. Too bad I deleted these files and don't have anymore :sad:
I'll ask to my bros if he has these files somewhere to make other experimentations
Sorry :o :o :o