SPRM 1: Current Audio Stream Number
The DVD specification allows for up to eight different audio streams. This SPRM lists the
current stream being played or the last one selected by the viewer.
The value range for this SPRM is 0 through 7, where 0 is the first stream and 7 is the last
SPRM 1 value
This information is useful when tracking which audio stream was last selected or played.
It is very useful when determining which button to highlight when jumping to a menu
where audio streams are selected. This is especially important if the viewer is allowed to
change the audio stream while viewing the movie.