While I saw this format mentioned in dexvert unsupported formats, I ignored it for confusing with RatDVD. And apparently it’s not me who should’ve paid attention—since it’s a format used in some of EA games (like SSN-21 Seawolf or Kasparov’s Gambit) it is Peter Ross who should’ve looked and REd it by now.
While the format is rather simple, it is still rather curious. Audio data seems to be coded using a mix of RLE and ADPCM (i.e. it allows coding a run of the same sample value or deltas that are scaled depending on the previous delta code value). Video can be coded as simple frame (raw or RLE) or split into two parts (each may be raw or RLE as well) and assembled back somehow. From what I see it uses one buffer as a source of pixels and another one as opcodes stream and invokes a runtime-generated code for those opcodes. So I’ll need to find out what gets generated first and then translate it to more conventional operations. Though I expect it to be something rather simple like telling how many pixels to skip. There’s another mode which seems to use flags to tell which lines of the previous frame to duplicate but could misunderstand it (after all, the standalone player code supports additional features like scaling during playback).
Of course I intend to document it and add this format support to na_game_tool eventually.