@istvan @genmaicha I found out none of them actually had the data set, the fields were there and were set to be zero-length, but then for no good reason, the space allocated for those fields was filled with gibberish.

furthermore I found out that much of what I was trying to do was impossible because docs implied there was a compressed and uncompressed version of the file format--but I eventually learned that it really only uncompressed to memory, the docs said "do this for uncompressed" but after analysis of the actual playback code, there was no support for it.