Kostya has ironed out the details of the Duck TrueMotion 2 video codec format and finished the FFmpeg decoder. Now it is possible to natively decode all 100+ AVI files on the PC version of Final Fantasy VII:
Check out the FFmpeg CVS repository.
Kostya has plodded through the long-open sourced, yet highly cryptic, code of On2’s VpVision and successfully reverse engineered a description of the Duck TrueMotion 2 video codec (fourcc: TM20). He then re-implemented a fresh version which is available in the FFmpeg CVS repository. Here it is in action, decoding the one known TM20 sample:
The video depicts something related to the unkillable Final Fantasy game series. The most famous application for the TM20 codec has been to encode the FMV in Eidos’ PC port of Final Fantasy VII. This game is known to use a bitstream-incompatible version of the TM20 format. So there is still some work to do on this codec before the Final Fantasy fanboys rejoice over being able to natively decode the FMV for this game.
Also, do you remember the basic Autodesk FLIC format? Did you know there are more variations of the format than you can possibly imagine? As much as I enjoy hacking on esoteric multimedia formats I just could not bring myself to care about these variations. This is mostly because I did not have sample files.
Recently, however, Steven Johnson has seen fit to implement several variations of the format including FLX and DTA extensions. The code is in FFmpeg’s CVS.
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Do you have any idea how long I have been involved in multimedia hacking and reverse engineering? About 5 years now. All that while, folks have warned me sternly, and constantly, that this type of work would get me sued to death. I am pleased to announce that today I received my first legal threat. I feel that my work has finally been validated!
Well, it was not necessarily a legal threat, like those notorious “nastygram” cease & desist letters. It was more like a veiled reference to a possible future legal threat. Someone identifying himself as the assistant general counsel for On2 said that the company took exception to the fact that I was posting decompilations of their Java decoder. And just when I was starting to feel that no one cared about my work… |
Naturally, this raises some pressing questions. First and foremost, why was I contacted by the assistant general counsel? Why doesn’t my case warrant the attention of the lead/primary/head general counsel? Maybe if I went after their latest generation codec, VP7, my actions would merit an escalation.
For the time being, I have decided to not post the Java decompilations on my Practical Reverse Engineering site. This entire site is partially an experiment to test where the limits are. Looks like we found one such limit.
I never had a compelling reason to research legal options surrounding these RE activities. Maybe it is time to start. But I am just so lazy… As always, this subject may be revisited. Feel free to email me regarding this situation.
I am pleased to report that people have been jumping on the decompiled Java-based VP5 decoder. Notably, it was clear to one individual that the method called clinch() that read bits from the stream using some bizarre algorithm is, in fact, an arithmetic decoding algorithm.
Regarding credits: I realize that many people engaged in reverse engineering activities are a little paranoid about having their achievements recognized. As such, my default policy is to not mention a contributor’s name unless they specifically ask for credit.
This is the current version of the decompiled VP5 Java cryptogram. Updates may occur at any time so check on the version number and timestamp inserted by SVN.