[Scummvm-devel] SCI: Patch files from SQ5/German

[Lars Skovlund]

On Thu, Jul 09, 2009 at 05:18:52AM -0700, M. Kiewitz wrote:
> 
> Hi there,
> 
> I just debugged around on SQ5/German, because the game normally says something about "view 96 not found" and exits.
> 
> Now view 96 actually exists, I debugged further and the problem is
> with all views loaded from patches. They don't exist in the actual
> resource file.  

The first thing to notice is that patch files aren't compressed. Since
a large part of decompressing SCI1.1 views consists of reordering the
internal file structure, you can get a very good idea of what the file
format looks like by inspecting the decompression code. It currently
lives in sci/decompressor.cpp - the relevant method being
DecompressorLZW::reorderView(). From that - and comparing with games
from other platforms and with the SCI Studio source code - you'll see
that the second byte contains an indication of the color format used
in that view. It's 0x80 on the PC platform, but I seem to remember it
being 0x40 in Amiga games. I've never worked on amiga support myself,
though. 

> Anyone has a clue whats going on here? SCIView has no problem reading those. Perhaps 2nd byte is header size up to (?) 24 bytes??

It is true that some versions of SCI had support for extra bytes in
the header; I think Christoph added the support. But what seems
obvious is that not all SCI versions support this. A deeper
investigation into which versions need this and which do not seems in
order. 

> Regards
>   M. Kiewitz

Lars