Dim $In = "BWAABBBWAABWWWAABWAAAAAABWAABWAABWAA"
Dim $Out = ""

Dim $Char = StringSplit($In,"")
Dim $Buffer = "", $i = 1
Dim $Result[1]

While $i <= $Char[0]
	$Buffer &= $Char[$i]
	
	If ($i+1 <= $Char[0]) AND (Not ($Char[$i] == $Char[$i+1])) Then
		_Add($Buffer)
		$Buffer = ""
	EndIf
	
	$i += 1
WEnd
_Add($Buffer)

For $i = 1 to UBound($Result)-1
	If (StringLen($Result[$i]) == 1) Then
		$Out &= $Result[$i]
	Else
		$Out &= StringLen($Result[$i]) & StringLeft($Result[$i],1)
	EndIf
Next

ConsoleWrite("String length before: " & StringLen($In) & @CRLF)
ConsoleWrite("String length after: " & StringLen($Out) & @CRLF)
ConsoleWrite("KB saved: " & ((StringLen($In)-StringLen($Out))/1024) & " ( " & (StringLen($In)-StringLen($Out)) & " bytes or " & Round((StringLen($In)-StringLen($Out))/StringLen($In)*100,1) &  "% )" & @CRLF)
ConsoleWrite("In : " & StringLeft($In,100) & @CRLF)
ConsoleWrite("Out: " & StringLeft($Out,100) & @CRLF)

Func _Add($String)
	$n = UBound($Result)
	Redim $Result[$n+1]
	$Result[$n] = $String
EndFunc