deal with relative path

bin/oxtimeline

@@ -1,6 +1,6 @@
 #!/usr/bin/python
-# -*- coding: utf-8 -*-
-# vi:si:et:sw=4:sts=4:ts=4
+# -*- coding: utf-8 -*-
+# vi:si:et:sw=4:sts=4:ts=4
 # GPL 2008
 
 import os
@@ -27,6 +27,7 @@ if __name__ == '__main__':
     if None in (opts.prefix, opts.input):
         parser.print_help()
         sys.exit()
+    opts.input = os.path.abspath(opts.input)
 
     timeline = oxgst.Timeline(opts.input)
     timeline.extract(opts.prefix, opts.width, opts.height)