Normally, when they allocate a VagCmd, they do a bunch of stuff to clear
all the status bits and reset things
in particular the InitVAGCmd function does a lot
but for the stereo command, they do a lot less:
Which means that the new_stereo_command can just have random status bits
left over from whatever the last user had.
we seem to end up in a state where byte21 is set, and this causes
everything else to be wrong and off-by-one dma transfer. My guess is
that the original game avoided this bug due to lucky timing that I don't
understand.
I think the fix of just clearing byte21 is ok because there's no way
that the old value of the byte is useful after the command is
repurposed.
Saves 16 bits and lets us align the `color_index` field properly.
This shouldn't improve or decrease performance by any noticeable amount
except maybe in really low end systems.
Tyler Wilding