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Bleech Studios, posted Fri Feb 12, 2021 12:44 pm (62146)

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i want to compress with a raw deflate stream with zlib but whenever I do it comes out with some weird header '2q..', I need the header to be 0xED like I normally see (complicated to explain). Im using zlib 1.2.8 and this version should do it.
I use this for deflate init:

Code:

deflateInit2(&stream, 1, Z_DEFLATED, -15, 1, Z_FILTERED);

. Most deflate streams start with a 0xe*, so why isnt it giving me that? the stream is valid, i checked using offzip.

Basically, if anyone can find the exact options for zlib (ive tried many) and version of zlib on the want_unpack.dat to get the want.dat then thats what Im aiming for

aluigi, posted Fri Feb 12, 2021 3:50 pm (62149)

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Have you tried the default deflateInit or the following?

Code:

deflateInit2(&stream, 9, Z_DEFLATED, -15, 9, Z_FILTERED)

packzip is quite useful for these tests: packzip -w -15 -m 1 want_unpack.dat output.dat
Both -m 1 and -m 3 gives the initial 0xed that you want.

I don't think it makes any difference in decompression, I'm just answering to your request

Bleech Studios, posted Fri Feb 12, 2021 5:37 pm (62150)

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Thanks aluigi that worked!!