#! /usr/bin/python
import sys, os
# Compares Qtractor Normalize with an Alternative Normalize
# written by dave@multitrack.co.nz

#**************************************
def QtrNorm(nVelo, percent, value, mxVelo):
    rtn = 0

# Formula: normalized_value = value * (param_percent * param_value) / (100 * max_value)
    w = percent * value
    x = 100 * mxVelo

    y = nVelo * (w / x)
    z = round(y)
    rtn = str(z)

    return rtn

#**************************************
def AltNorm(nVelo, percent, target, mxVelo):
    rtn = 0

# Recommend using compression ratio eg: 2:1, 3:1, 4:1, 6:1, 8:1 etc
# Converted to a percentage for this test, to match Qtractor input.
    compress = 100 / percent

# Prevent negative velocity, when re-scaling
    dff = mxVelo - target
    if dff > 0:
        compress = mxVelo / target

# Formula: normalized_value = (note_velo / compress_ratio) + gain

# Calculate gain
    gain = target - (mxVelo / compress)

# Compress and Normalize
    x = (nVelo / compress) + gain
    y = round(x)
    rtn = str(y)

    return rtn

#**************************************
# Run process
print('\n**** Compare Normalization ****')

# User Inputs
x = input('Compress data (percentage): ')
percent = int(x)

x = input('New max velocity (1-127): ')
value = int(x)
print()

# Note: In the real world, mxVelo would not exceed the range of nVelo.
mxVelo = nVelo = 127

while nVelo >= 0:
    qtr = QtrNorm(nVelo, percent, value, mxVelo)
    alt = AltNorm(nVelo, percent, value, mxVelo)
    print('Note Velocity:',nVelo,'\tQtr Norm Value:',qtr,'\tAlt Norm Value:',alt)
    nVelo -= 2

# My conclusion: The Alt Normalizer produces the best result, 
# for the most common use of a Bass or Keys playing with Drums.
# (2:1 or 50%) data spread and a reduced max velocity.

# Foot note a velocity of 0 in MIDI is a NOTE_OFF.