As I mentioned in a recent post, I’ve tried using discmaster.textfiles.com to search for more exotic multimedia formats. Here’s a short report of the found formats of some interest.
I mostly looked at the formats listed as video but that could not be decoded. Or audio-only AVIs—some of them are really audio-only, others feature a video stream that was not recognized.
So, what I’ve found:
- DK Animation—this turned out to be a simple RLE-based animation+sound format used in some interactive encyclopedias. It was rather easy to figure out format from the samples, while executables were rather useless (due to program design it’s next to impossible to locate the code responsible for animation handling without decompiling all of it;
- PI-Video (used in a different set of interactive encyclopedias) turned out to be a simple quadtree-based codec (frame is divided into square tiles, each tile can be skipped, filled with one colour, subdivided further or, in case of 4×4 tile, filled with raw image). Additionally pixel values may be further compressed with LZW. That proved out to be the most interesting format out of the bunch;
- there were a bunch of RIFF and IFF-based formats, often without a known decoder. Maybe I’ll look at them one day when I feel really desperate, but not today;
ESCPcodec is a variation of Escape 130. After I changed FOURCC to the recognizedE130the file was somewhat decoded: there were countless decoding errors, visual garbage yet it produced almost perfect complex parts of the frame as well. I suspect it may have e.g. an additional field or two or some small bitstream tweaks;- and a special mention to
tmotFOURCC which of course turned out to be TrueMotion 1 video.
It’s random finds like this that make life a bit less dull.
Cool post, I love reading about reverse engineering efforts of old formats. I’ve RSS subbed.
discmaster utilizes dexvert to do it’s conversions and dexvert maintains a list of ‘unsupported’ formats: https://github.com/Sembiance/dexvert/blob/master/UNSUPPORTED.md
If you scroll down to the bottom of that page you’ll see a bunch of video formats that there exists no modern converter for. Some of them you’ve already discovered.
The work you’ve been doing in reverse engineering them, do you have code or any documentation on them anywhere? Would love to see a modern converter for them.
Thanks for the pointer, I’ll look at it.
As for the documentation, it’s either wiki.multimedia.cx or this blog (when there’s not much to describe or the format does not fit the wiki).
And if I get a request for some specific format (not that it happens often) I’ll look at it and try to produce at least some description if not a working decoder.