Fix FFmpeg test in case FFmpeg was not available at compile time

xbob/io/test/test_video_codec.py

@@ -98,6 +98,8 @@ def test_format_codecs():
     distortions['mpeg2video']['color'] = 9.0
     distortions['mpeg2video']['frameskip'] = 1.4
 
+  from .._externals import versions
+  if versions['FFmpeg']['ffmpeg'] != 'unavailable':
     from .._externals import supported_videowriter_formats
     SUPPORTED = supported_videowriter_formats()
     for format in SUPPORTED:
@@ -179,6 +181,8 @@ def test_user_video():
       msmpeg4v2  = 2.3,
       )
 
+  from .._externals import versions
+  if versions['FFmpeg']['ffmpeg'] != 'unavailable':
     from .._externals import supported_videowriter_formats
     SUPPORTED = supported_videowriter_formats()
     for format in SUPPORTED:

xbob/io/test/utils.py

@@ -71,6 +71,7 @@ def ffmpeg_version_lessthan(v):
   indicated as a string parameter.'''
 
   from .._externals import versions
+  if versions['FFmpeg']['ffmpeg'] == 'unavailable': return False
   avcodec_inst= SV(versions['FFmpeg']['avcodec'])
   avcodec_req = ffmpeg_versions[v][0]
   return avcodec_inst < avcodec_req