When playing back a sound effect it is possible to modulate the sound to generate different effects (such as a fade in and out). The following defines the stereo volume of the sound.
The position is always given as if the sample data was defined with a rate of 44,100 bytes per seconds. For instance, the sample number 1 in a sound effect with a sample rate of 5.5K is given as position 8 in the envelope. All of these positions should be within the f_in_point and f_out_point.
Mono sound should use the same value for the left and right volumes. Note that it will automatically be averaged if necessary.
Note that the volume goes from 0 to 32768.