// x         -- the value to find
// arr       -- sorted array of Numbers
// [lo, hi)  -- the range of indices to search, lo is inclusive, hi is exclusive
//              so [5, 10) means consider 5,6,7,8,9
//
// The return value is the largest arr index whose value does not exceed x.
// e.g.  binarySearch_( 33.3, [0,10,20,30,40,50], 0, 6 ) returns 3
// e.g.  binarySearch_( 30.0, [0,10,20,30,40,50], 0, 6 ) returns 3
// e.g.  binarySearch_( 90  , [0,10,20,30,40,50], 0, 6 ) returns 5
// e.g.  binarySearch_( 0   , [0,10,20,30,40,50], 0, 6 ) returns 0
// e.g.  binarySearch_( -90 , [0,10,20,30,40,50], 0, 6 ) returns -1
function binarySearch_( x:Number, arr:Array, lo:Number, hi:Number ) : Number
{
	if ( hi - lo < = 1 )
	      return x < arr[lo] || hi - lo < 1 ? -1 : lo;
	var mid:Number = Math.floor((lo+hi)/2);
	return x< arr[mid] ? binarySearch_( x, arr, lo, mid )
	                   : binarySearch_( x, arr, mid, hi );
}
 
// wrapper
function binarySearch( x:Number, arr:Array ) : Number
{
	return binarySearch_( x, arr, 0, arr.length );
}
 
trace( binarySearch( 33.3 , [0,10,20,30,40,50] ) ); // 3
trace( binarySearch( 30.0 , [0,10,20,30,40,50] ) ); // 3
trace( binarySearch( 90   , [0,10,20,30,40,50] ) ); // 5
trace( binarySearch( 0    , [0,10,20,30,40,50] ) ); // 0
trace( binarySearch( -90  , [0,10,20,30,40,50] ) ); // -1
stop();

/**
 * Loops through an array of seekpoints to find a requested time. 
 * If the value is found within the array of seekpoints the index at which 
 * the value is found is returned. If an exact match is not found, -1 is returned 
 * and the the upper and lower indices between which the value falls are set 
 * (so you can determine the closest indice, or seek to to the nearest indexed 
 * time behind or forward in the array of seekpoints.
 * 
 * Seekpoints array must be sorted.
 * 
 * @param value  the requested seek time to find
 * @param range the array of seekpoints collected from an MPEG-4 AVC NetStream metadata event
 * @param the low index within the range we'd like to scan
 * @param the high index within the range we'd like to scan
 * 
 */
public function search( value:Number, range:Array, low:int, high:int ):int
{
    var val:int = -1;
    var time:Number;
    while ( low < = time  )
    {
       var median:int = ( low + high ) / 2;
       time = range[median].time;
       if ( value > time  )
       {
          low = median + 1;
       }
       else if ( value < time  )
       {
          high = median - 1;
       }
       else // found a match
       {
          low = median;
          high = median;
          val = median;
          break;
       }
   }
   _upperBounds = low;
   _lowerBounds = high;
   return val; // failed to find value. Look at the upper / lower bounds
}