#!/usr/bin/python
import os
os.environ["PATH"] = os.pathsep + '/usr/bin'
from pydub import AudioSegment
import numpy as np
import sys
import math

attenuate_db = 0
accentuate_db = sys.argv[3]


def bass_line_freq(track):
    sample_track = list(track)

    # c-value
    est_mean = np.mean(sample_track)

    # a-value
    est_std = 3 * np.std(sample_track) / (math.sqrt(2))

    bass_factor = int(round((est_std - est_mean) * 0.005))

    return bass_factor

sample = AudioSegment.from_mp3(sys.argv[1])
filtered = sample.low_pass_filter(bass_line_freq(sample.get_array_of_samples()))

combined = (sample - attenuate_db).overlay(filtered + accentuate_db)
combined.export(sys.argv[2], format="mp3")