NPI, in layman's terms, relates to the non-purcussive elements within a song. Percussion may generally consist of a beat, and other sounds that occur every beat, or sounds that occur on the off-beat.
Non-percussive elements may include vocals, guitar riffs, synth sounds, etc.
When manually beat mixing, it is the job of the DJ to ensure that the two songs being mixed don't "clash". Clashing can occur when non-percussive elements are played over the top of each other.
The following examples would clash during a beat mix...
Guitar riff over another guitar riff
Vocals over vocals
Synth over Synth
Guitar over Synth
...and so on.
Basically, it is safe to mix a beat over another beat, but not if both beats contain non-percussive elements. Sometimes, it's necessary to beat mix a song with some NP (Non-Percussive) elements into another song with NP elements. The NPI values help OtsAV determine how to mix two songs together.
The Pre-NPI and Post-NPI values can be set to reflect the Intensity of any Non-Percussive elements within a certain range of the song. These values are used within OtsAV during an automated beat mix, to adjust the volume of each song during the beat mix, so that clashing doesn't occur.
Pre-NPI: The Non-Percussive Intensity of the Range area before the Match Point marker. Any number from 0 to 100 is valid.
Post-NPI: The Non-Percussive Intensity of the Range area after the Match Point marker. Any number from 0 to 100 is valid.
Determining the values to enter in the Pre and Post NPI boxes
NPI values range from 0 (lowest) to 100 (highest).
A club mix version of a song may begin with only a beat, and no other instrumentation. Effectively, there are no sounds that are non-percussive. Therefore you could say there is zero Non-Percussive-Inensity. In this example, you would enter 0 (zero) in the Pre-NPI box for the Intro Range.
All audio prior to the Match Point should be considered when setting Pre-NPI values. If the Intro of the club song changes before the Match Point, and a synth sound is introduced, the Pre-NPI value should be increased.
The same principles can be applied for the Post-NPI value, and the NPI values for the Outro Range.
This may take a little practice, as one person may feel one part of a song is "busy", where as another person may not. The following are some guidelines to help you get started. If you have the following songs in your Media Library, play the sections described, and you may get a better understanding of the NPI concept.
Yeah by Usher
Intro Pre-NPI (from 0:01.2 seconds to 0:10.3 seconds): 10
Intro Post-NPI (0:10.3 to 0:19.5): 60
Outro Pre-NPI:(3:31.5 to 3:49.8): 90
Outro Post-NPI (3:49.8 to end): 0
Show me how to setup the Beat chunk for this song.
Get The Party Started by Pink
Intro Pre-NPI (from 0:01.0 seconds to 0:09.8 seconds): 30
Intro Post-NPI (0:09.8 to 0:23.4): 70
Outro Pre-NPI:(2:46:0 to 3:03.0): 80
Outro Post-NPI (3:03.0 to end): 0
Show me how to setup the Beat chunk for this song.
Get Ready For This 2006 [4Play Filthy Club Mix] by 2 Unlimited
Intro Pre-NPI (from 0:00.0 seconds to 0:59.1 seconds): 10
Intro Post-NPI (0:59.1 to 1:13.0): 30
Outro Pre-NPI:(6:39.0 to 7:08.0): 50
Outro Post-NPI (7:08.0 to 7:36.0): 0
Show me how to setup the Beat chunk for this song.