[ffmpeg] Make available a property

youtube_dl/YoutubeDL.py

@@ -1301,7 +1301,7 @@ class YoutubeDL(object):
                     downloaded = []
                     success = True
                     merger = FFmpegMergerPP(self, not self.params.get('keepvideo'))
-                    if not merger.available():
+                    if not merger.available:
                         postprocessors = []
                         self.report_warning('You have requested multiple '
                                             'formats but ffmpeg or avconv are not installed.'

youtube_dl/postprocessor/ffmpeg.py

@@ -34,7 +34,7 @@ class FFmpegPostProcessor(PostProcessor):
         self._determine_executables()
 
     def check_version(self):
-        if not self.available():
+        if not self.available:
             raise FFmpegPostProcessorError('ffmpeg or avconv not found. Please install one.')
 
         required_version = '10-0' if self._uses_avconv() else '1.0'
@@ -108,6 +108,7 @@ class FFmpegPostProcessor(PostProcessor):
                 self.probe_basename = p
                 break
 
+    @property
     def available(self):
         return self.basename is not None