Since I’ve done all improvements to NihAV that I wanted to do (beside vague “improve Indeo 3 encoder somehow” or “add some interesting format support”), I decided to look at the formats in my backlog and discovered that I have a QPEG player with a couple of DVC samples. Considering that I’ve REd their VfW codec over two decades ago, I had to look at this as well.
It turned out to be a straightforward format with static palette and video frames packed with moderately complex RLE (it has opcodes for run/copy/skip and literals). The most interesting thing there to me was that values without high bit set are treated as literals, or rather as indices in the remapping table (which is the first 128 bytes of a frame). Considering that low 20 colours of the palette seem to be unset, it makes some sense.
The hardest part was to read the binary specification. The executable uses Phar Lap 386 extender, so it’s actually stored in P3 format right after the loader. At least I have some experience with loading such formats when I messed with Linear eXecutable format before Ghidra plugins were available (and sometimes afterward as well, since e.g. neither of two known plugins managed to load Wing Nuts executable). Also I managed to spot that 0xE0 byte happens at the end of packed frame, so I guessed it was the end data marker and searched for the code using it as such. I’ve managed to locate four RLE decompression functions, all probably functionally identical, and after figuring out other details (like where remap table comes from) I ended up with the decoder that works on all four known samples just fine.
Overall, it’s nothing particularly complex but it was still nice to look at.
I just now got intel about PCA, (Sony Perfect Clarity Audio), can you do RE of it?
I will be eternally grateful for your valuable intel.
I’ll gladly take a look if it’s not protected. I can’t promise any results but a look I can always take.