Having only read through your code once, I'm not clear as to why you're trying to compress stuff in chunks. You're also doing this as a web page, which complicates things.

My suggestion would be to get the compression code figured out from the command line, and once that's working properly, use that code to build a web page.

From a code smell point of view, you don't need 1; at the end of a script -- that's only required for modules, since they are used by scripts, and that usage wants to return TRUE, aka 1.

For a posting to this site, I'd also recommend deleting any development code that's commented out .. it's useful to you, but isn't pertinent. Ideally, a code posting is a slimmed down, as-simple-as-possible example that shows the specific problem.