To the best of my knowledge, I have finished documenting both the GDV file format and the associated video coding format. Now let’s see who can first implement a file demuxer and video decoder for the format. Remember, samples are here.

The only part of the video decoding process that gives me pause is in coding method 8 where the decoder copies a run a pixels from an offset that’s further in the image buffer than the current decoded offset. I believe this is assuming that the current buffer also holds the previously decoded frame. If true, this constitutes a run-based interframe motion compensation scheme.

I have written some more documentation for the GDV file format. VAG’s decoding functions are pretty straightforward but the documentation process gets tedious in a hurry. The more advanced coding methods use a bizarre bit packing method interleaved with data bytes that I can almost guarantee FFmpeg does not support with its native bitstream readers.

I have the game Realms Of The Haunting which is 4 CD-ROMs packed full of FMV goodness using the GDV format. Two other games, Hardwar and Normality, are known to use the GDV format, but with other color depths and perhaps other coding modes. If anyone has those games, I would like to see some GDV samples from each.