diff --git a/SLAM/Form1.vb b/SLAM/Form1.vb
index bb18534..55f2b53 100644
--- a/SLAM/Form1.vb
+++ b/SLAM/Form1.vb
@@ -165,7 +165,12 @@ Public Class Form1
         Dim convert As New FFMpegConverter()
         convert.ExtractFFmpeg()
 
-        Dim command As String = String.Format("-i ""{0}"" -f wav -flags bitexact -map_metadata -1 -vn -acodec pcm_s16le -ar {1} -ac {2} -ss {3} -t {4} -af ""volume={5}"" ""{6}""", Path.GetFullPath(inpath), samplerate, channels, starttrim, length, volume, Path.GetFullPath(outpath))
+        Dim trimstring As String
+        If length > 0 Then
+            trimstring = String.Format("-ss {0} -t {1} ", starttrim, length)
+        End If
+
+        Dim command As String = String.Format("-i ""{0}"" -f wav -flags bitexact -map_metadata -1 -vn -acodec pcm_s16le -ar {1} -ac {2} {3}-af ""volume={4}"" ""{5}""", Path.GetFullPath(inpath), samplerate, channels, trimstring, volume, Path.GetFullPath(outpath))
         convert.Invoke(command)
     End Sub