417
edits
Difference between revisions of "Cine/Specifications"
Jump to navigation
Jump to search
Added more detail to chapter title "Compression format" with "Compression format (Bytekiller 1.3)".
m (→.ADL files: consistency change.) |
(Added more detail to chapter title "Compression format" with "Compression format (Bytekiller 1.3)".) |
||
| (2 intermediate revisions by the same user not shown) | |||
| Line 305: | Line 305: | ||
</pre> | </pre> | ||
===Compression format=== | ===Compression format (Bytekiller 1.3) === | ||
The compression algorithm used by all Delphine's adventure games uses | The compression algorithm used by all Delphine's adventure games uses | ||
sliding window compression (Quite like [http://en.wikipedia.org/wiki/LZ77 LZ77]) | sliding window compression (Quite like [http://en.wikipedia.org/wiki/LZ77 LZ77]) | ||
combined with a fixed non-adaptive [http://en.wikipedia.org/wiki/Entropy_coding entropy coding] scheme | combined with a fixed non-adaptive [http://en.wikipedia.org/wiki/Entropy_coding entropy coding] | ||
scheme. It seems that the algorithm is [http://www.pouet.net/prod.php?which=47994 Bytekiller 1.3]. | |||
This is based on comparing the reverse engineered | |||
[https://github.com/scummvm/scummvm/blob/branch-2-0-0/engines/cine/unpack.cpp#L92 decompression routine] | |||
in ScummVM with the | |||
[https://github.com/aperture-software/colditz-escape/blob/v1.2/low-level.c#L150 uncompress]-function | |||
from [https://github.com/aperture-software/colditz-escape Colditz Escape]'s source code. | |||
The compressed data is in big endian 32-bit chunks, working backwards from the buffer's end. | The compressed data is in big endian 32-bit chunks, working backwards from the buffer's end. | ||