Kostya's Boring Codec World

Since I was bored I tried to (ab)use discmaster.textfiles.com to search for interesting (i.e. unsupported) samples once again. The main problem is that if it does not decode contents it does not recognize the format. So e.g. AVI files without video track (yes, those files exist) and those using some unrecognized codec will be both marked as aviAudio format, and if audio stream is absent or unknown as well the file gets demoted to unknown.

So I tried to search AVI and MOV files both by extension and by this audio-only type and here are the categories of the results:

• actual audio-only files (that’s expected);
• completely different format (there’s an alternative AVI format and MOV is very popular extension as well);
• improperly extracted files (rather common with MOV on hybrid Macintosh/PC CDs where resource fork often gets ignored);
• damaged files (happens with some CDs and very common with AOL file library collection—often AVI data starts somewhere in the middle of the file);
• too old or poorly mastered files (for example, one AVI file lacks padding to 16 bits between chunks; some MOV files can’t be decoded while they look correct);
• one Escape 130 that could’ve been supported if libavcodec AVI demuxer would not feed garbage to the decoder (it’s not just my demuxer that can handle it, old MPlayer 2 plays it fine with its own demuxer);
• some TrueMotion 1 files that were not recognised because of tmot FOURCC;
• files with some special features of the known codecs (I’ve seen some MOV files containing QDraw codec with JPEG frames);
• files with the codecs I can decode (like IPMA) but the popular software can’t;
• files with the known codecs (some documented by me) that nobody bothered to implement (especially Motion Pixels 1 and 2);
• and finally some AVIs with savi FOURCC and a single file with DKRT FOURCC.

Those “SuperAVI” files turned out to be a rebranded Cinepak which I managed to recognise right away, the remaining file turned out to be a bit baffling. After extracting the frames I figured out that it is raw YV12 video, but for some reason it had 64 bytes of soemthing before the image data and 440 bytes after. It can be located on TNG Klingon Language Disc but it does not look like the software there can decode it anyway.

Overall, nothing hard or interesting (if you don’t count the questions about the origins of that file, that is).

This entry was posted on Saturday, June 29th, 2024 at 12:45 pm and is filed under Various Video Codecs. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.