Compressing multiple files/folder via stdin

[cnrayz]

this topic seems to be duplicated as "Adding multiple files via stdin" https://sourceforge.net/p/sevenzip/discussion/45797/thread/128e8351/

what i wanna do is, using 7zip to decompress a package to stdout, piping to stdin of 7zip to compress into a new package, while the input and output packages are in different formats. it's kind of converting one package to another, without writing temp files on disk.

if the input package contains one single file, then it's easy, according to the manual, using:
7z x "c:\file1.zip" -so | 7z a -si"Doc1.txt" "c:\file2.7z"
-si"Doc1.txt" tells 7zip the filename, otherwise there'd be no name
zip and 7z are for example, maybe in other formats, like txz, tgz

now if the input package contains some structure, folder and files, how do i pass them via pipe, without extracting temp files to disk?

[Igor Pavlov]

no way in 7-zip