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LoadUtil

Kind of class:	public class
Package:	org.casalib.util
Inherits from:	none
Version:	01/08/09
Author:	Aaron Clinger, Mike Creighton
Classpath:	org.casalib.util.LoadUtil
File last modified:	Thursday, 08 January 2009, 17:53:21

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/*
    CASA Lib for ActionScript 3.0
    Copyright (c) 2009, Aaron Clinger & Contributors of CASA Lib
    All rights reserved.
    
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:
    
    - Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
    
    - Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
    
    - Neither the name of the CASA Lib nor the names of its contributors
      may be used to endorse or promote products derived from this software
      without specific prior written permission.
    
    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/
package org.casalib.util {
    import org.casalib.util.ConversionUtil;
    import org.casalib.util.NumberUtil;
    import org.casalib.math.Percent;
    
    /**
        Utilities for calculating a load's speed and progress.
        
        @author Aaron Clinger
        @author Mike Creighton
        @version 01/08/09
    */
    public class LoadUtil {
        
        
        /**
            Calculates the load speed in bytes per second (Bps).
            
            @param bytesLoaded: Number of bytes that have loaded between {@code startTime} and {@code elapsedTime}.
            @param startTime: Time in milliseconds when the load started.
            @param elapsedTime: Time in milliseconds since the load started or time when load completed.
            @return Bytes per second.
            @usageNote This method returns BYTES per second, not bits per second.
        */
        public static function calculateBps(bytesLoaded:uint, startTime:uint, elapsedTime:uint):int {
            return Math.max(0, (bytesLoaded / ConversionUtil.millisecondsToSeconds(elapsedTime - startTime)));
        }
        
        /**
            Calculates the load speed in kilobytes per second (kBps).
            
            @param bytesLoaded: Number of bytes that have loaded between {@code startTime} and {@code elapsedTime}.
            @param startTime: Time in milliseconds when the load started.
            @param elapsedTime: Time in milliseconds since the load started or time when load completed.
            @return Kilobytes per second.
            @usageNote This method returns kiloBYTES per second, not kilobits per second.
        */
        public static function calculateKBps(bytesLoaded:uint, startTime:uint, elapsedTime:uint):Number {
            return ConversionUtil.bytesToKilobytes(LoadUtil.calculateBps(bytesLoaded, startTime, elapsedTime));
        }
        
        /**
            Calculates the percent the video has buffered.
            
            @param bytesLoaded: Number of bytes that have loaded between {@code startTime} and {@code elapsedTime}.
            @param bytesTotal: Number of bytes total to be loaded.
            @param startTime: Time in milliseconds when the load started.
            @param elapsedTime: The current time in milliseconds or time when load completed.
            @param lengthInMilliseconds: The total duration/length of the video in milliseconds.
            @return The percent buffered.
        */
        public static function calculateBufferPercent(bytesLoaded:uint, bytesTotal:uint, startTime:uint, elapsedTime:uint, lengthInMilliseconds:uint):Percent {
            var totalWait:Number           = bytesTotal / (bytesLoaded / (elapsedTime - startTime)) - lengthInMilliseconds;
            var millisecondsRemaining:uint = LoadUtil.calculateMillisecondsUntilBuffered(bytesLoaded, bytesTotal, startTime, elapsedTime, lengthInMilliseconds);
            
            return (totalWait == Number.POSITIVE_INFINITY) ? new Percent(0) : new Percent(NumberUtil.constrain(1 - millisecondsRemaining / totalWait, 0, 1));
        }
        
        /**
            Calculates the remaining time until the video is buffered.
            
            @param bytesLoaded: Number of bytes that have loaded between {@code startTime} and {@code elapsedTime}.
            @param bytesTotal: Number of bytes total to be loaded.
            @param startTime: Time in milliseconds when the load started.
            @param elapsedTime: The current time in milliseconds or time when load completed.
            @param lengthInMilliseconds: The total duration/length of the video in milliseconds.
            @return The amount millisecond that remain before the video is buffered.
        */
        public static function calculateMillisecondsUntilBuffered(bytesLoaded:uint, bytesTotal:uint, startTime:uint, elapsedTime:uint, lengthInMilliseconds:uint):uint {
            return Math.max(Math.ceil((bytesTotal - bytesLoaded) / (bytesLoaded / (elapsedTime - startTime))) - lengthInMilliseconds, 0);
        }
    }
}

Utilities for calculating a load's speed and progress.

Summary

Class methods

calculateBps (bytesLoaded:uint, startTime:uint, elapsedTime:uint) : int
- Calculates the load speed in bytes per second (Bps).
calculateKBps (bytesLoaded:uint, startTime:uint, elapsedTime:uint) : Number
- Calculates the load speed in kilobytes per second (kBps).
calculateBufferPercent (bytesLoaded:uint, bytesTotal:uint, startTime:uint, elapsedTime:uint, lengthInMilliseconds:uint) : Percent
- Calculates the percent the video has buffered.
calculateMillisecondsUntilBuffered (bytesLoaded:uint, bytesTotal:uint, startTime:uint, elapsedTime:uint, lengthInMilliseconds:uint) : uint
- Calculates the remaining time until the video is buffered.

Class methods

calculateBps

public static function calculateBps (

bytesLoaded:uint, startTime:uint, elapsedTime:uint) : int

Calculates the load speed in bytes per second (Bps).

Parameters:

bytesLoaded:

Number of bytes that have loaded between startTime and elapsedTime.

startTime :

Time in milliseconds when the load started.

elapsedTime:

Time in milliseconds since the load started or time when load completed.

Returns:

Bytes per second.

Usage note:

This method returns BYTES per second, not bits per second.

calculateBufferPercent

public static function calculateBufferPercent (

bytesLoaded:uint, bytesTotal:uint, startTime:uint, elapsedTime:uint, lengthInMilliseconds:uint) : Percent

Calculates the percent the video has buffered.

Parameters:

bytesLoaded :

Number of bytes that have loaded between startTime and elapsedTime.

bytesTotal :

Number of bytes total to be loaded.

startTime :

Time in milliseconds when the load started.

elapsedTime :

The current time in milliseconds or time when load completed.

lengthInMilliseconds:

The total duration/length of the video in milliseconds.

Returns:

The percent buffered.

calculateKBps

public static function calculateKBps (

bytesLoaded:uint, startTime:uint, elapsedTime:uint) : Number

Calculates the load speed in kilobytes per second (kBps).

Parameters:

bytesLoaded:

Number of bytes that have loaded between startTime and elapsedTime.

startTime :

Time in milliseconds when the load started.

elapsedTime:

Time in milliseconds since the load started or time when load completed.

Returns:

Kilobytes per second.

Usage note:

This method returns kiloBYTES per second, not kilobits per second.

calculateMillisecondsUntilBuffered

public static function calculateMillisecondsUntilBuffered (

bytesLoaded:uint, bytesTotal:uint, startTime:uint, elapsedTime:uint, lengthInMilliseconds:uint) : uint

Calculates the remaining time until the video is buffered.

Parameters:

bytesLoaded :

Number of bytes that have loaded between startTime and elapsedTime.

bytesTotal :

Number of bytes total to be loaded.

startTime :

Time in milliseconds when the load started.

elapsedTime :

The current time in milliseconds or time when load completed.

lengthInMilliseconds:

The total duration/length of the video in milliseconds.

Returns:

The amount millisecond that remain before the video is buffered.