XeNTaX Forum Index
Forum MultiEx Commander Tools Tools Home
It is currently Sun Feb 18, 2018 10:13 am

All times are UTC + 1 hour

Forum rules

Please click here to view the forum rules

Post new topic Reply to topic  [ 3 posts ] 
Author Message
 Post subject: MECC Bitmap Compression
PostPosted: Sun Sep 11, 2016 4:18 pm 

Joined: Wed Sep 23, 2009 5:16 pm
Posts: 30
Has thanked: 0 time
Have thanks: 0 time

You can make the ads go away by registering

Hey guys,

I've been trying to figure out how some bitmap files I extracted from an archive for the game "Opening Night" for quite some years now, and I'm closer than ever but still stumped. I was wondering if anyone here has ever heard of image compression like this.

The files are in a folder called "CBMP," so I'm 99.999% sure they're bitmaps. They have been heavily compressed. Some of the larger files contain multiple images within them (I think it's for animations in the program).

They have a custom 14 Byte header that has the following little endian values:

# of images in the CBMP file (short)
XSize (short)
YSize (short)
Offset of the Bitmap Data (long)
Size of the Bitmap Data (long)

After that is the bitmap data itself. A while back, someone said they looked like RLE bitmaps, but I think there's something else going on. From what I've researched, bitmaps draw their images in scanlines from the bottom up, or from the top down. When I modified some of the bitmap data just to see what it would do in the program, it appeared that the image was being drawn in 8 pixel chunks from the top left down. It would go down one column, then start the next column from the top again. Here's a picture to show you what I mean.

There are also separate files for the color palette. The palette is not encoded in any way, just the bitmap data.

I've included a link to some of the CBMP files and the color palette file here: http://s000.tinyupload.com/index.php?fi ... 1282341502

If anyone has a minute, I'd appreciate any info you'd have on compression like this. It seems like a weird custom thing, and I'm not sure how to go about reverse engineering it.


:twisted: jawharp :twisted:


You do not have the required permissions to view the files attached to this post. Register to gain access.

:twisted: jawharp :twisted:

 Post subject: Re: MECC Bitmap Compression
PostPosted: Mon Apr 24, 2017 7:45 am 

Joined: Mon Apr 26, 2010 6:51 am
Posts: 250
Has thanked: 61 times
Have thanks: 12 times
Bumping this so more people can look into reversing the game (and American Girls Premiere for that matter, no thanks to Lazy Game Reviews doing an episode on this).

 Post subject: Re: MECC Bitmap Compression
PostPosted: Tue May 16, 2017 12:59 pm 

Joined: Sat Oct 21, 2006 12:58 pm
Posts: 114
Has thanked: 5 times
Have thanks: 14 times

I looked shortly at it and came upon that, just a guess but could be interleaved RLE bitmap encoding perhaps, need some programmer try it all out.

Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC + 1 hour

Who is online

Users browsing this forum: No registered users and 1 guest

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group