LowPassBitrateEstimator

// Copyright 2012 David J Smith, Nanch LLC
// This code is available to the general public for use in personal or commercial products free of charge with no implied or explicit liability

// This code was used in [ EZ Drop ], a fast and easy way to get files to your droid
// https://market.android.com/details?id=co.dropper.ez.android.free

package co.dropper.ez.android.free;

import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;

public class LowPassBitrateEstimator {

    Queue<BitrateRecord> arrivals = new ConcurrentLinkedQueue<BitrateRecord>();

    long baseTime = System.currentTimeMillis();
    long millisecondInterval = 250;
    private double multiplier =  1000 / millisecondInterval;
    private double alpha = .96;
    long lastEstimatedTime = System.currentTimeMillis() - baseTime;
    double currentAverage = 0;

    public LowPassBitrateEstimator() {
    }

    public double estimate() {
        long now = System.currentTimeMillis() - baseTime;

        if (now - lastEstimatedTime < millisecondInterval) {
            return currentAverage * multiplier;
        }

        if (arrivals.size() == 0) {
            if (now > millisecondInterval) {
                for (int i = 0; i < (now - lastEstimatedTime)
                        / millisecondInterval; i++) {
                    currentAverage = alpha * currentAverage + (1 - alpha) * 0;
                    lastEstimatedTime += millisecondInterval;
                }
            }
        } else {


            long totalBytesReceived = 0;
            BitrateRecord br = new BitrateRecord();
            br = arrivals.peek();

            while (br.t < now - millisecondInterval) {
                while (br.t < lastEstimatedTime + millisecondInterval) {
                    totalBytesReceived += br.v;
                    arrivals.remove();
                    if (arrivals.size() == 0) {
                        break;
                    }
                    br = arrivals.peek();
                }

                currentAverage = alpha * currentAverage + (1 - alpha)
                        * totalBytesReceived;
                lastEstimatedTime += millisecondInterval;
                totalBytesReceived = 0;

                if (arrivals.size() == 0) {
                    break;
                }
            }
        }
        return currentAverage * multiplier;
    }

    public void push(int val){

        BitrateRecord br = new BitrateRecord();
        br.t = System.currentTimeMillis() - baseTime;
        br.v = val;
        arrivals.add(br);
    }
}



----------------------------- BEGIN BitrateRecord.java -----------------------------

package co.dropper.ez.android.free;
public class BitrateRecord {
    public long t;
    public long v;
}