{"id":2599,"date":"2010-07-14T20:55:55","date_gmt":"2010-07-15T03:55:55","guid":{"rendered":"http:\/\/multimedia.cx\/eggs\/?p=2599"},"modified":"2020-07-25T22:53:11","modified_gmt":"2020-07-26T05:53:11","slug":"brute-force-dimensional-analysis","status":"publish","type":"post","link":"https:\/\/multimedia.cx\/eggs\/brute-force-dimensional-analysis\/","title":{"rendered":"Brute Force Dimensional Analysis"},"content":{"rendered":"

I was poking at the data files of a really bad (is there any other kind?)<\/em> interactive movie video game known simply by one letter: D<\/em><\/a>. The Sega Saturn version of the game is comprised primarily of Sega FILM\/CPK files, about which I wrote the book<\/a>. The second most prolific file type bears the extension ‘.dg2’. Cursory examination of sample files revealed an apparently headerless format. Many of the video files are 288×144 in resolution. Multiplying that width by that height and then doubling it (as in, 2 bytes\/pixel) yields 82944, which happens to be the size of a number of these DG2 files. Now, if only I had a tool that could take a suspected raw RGB file and convert it to a more standard image format.<\/p>\n

Here’s the FFmpeg<\/a> conversion recipe I used:<\/p>\n

\r\n ffmpeg -f rawvideo -pix_fmt rgb555 -s 288x144 -i raw_file -y output.png\r\n<\/pre>\n
So that covers the files that are suspected to be 288×144 in dimension. But what about other file sizes? My brute force approach was to try all possible dimensions that would yield a particular file size. The Python code for performing this operation is listed at the end of this post.<\/p>\n
It’s interesting to view the progression as the script compresses to different sizes:<\/p>\n

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That ‘D’ is supposed to be red<\/a>. So right away, we see that rgb555(le) is not the correct input format. Annoyingly, FFmpeg cannot handle rgb5[5|6]5be as a raw input format. But this little project worked well enough as a proof of concept.<\/p>\n
If you want to toy around with these files (and I know you do), I have uploaded a selection at: http:\/\/multimedia.cx\/dg2\/<\/a>.<\/p>\n
Here is my quick Python script for converting one of these files to every acceptable resolution.<\/p>\n
work-out-resolution.py:
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