support special value "none" to not load any video encoders or csc mo…

…dules

git-svn-id: https://xpra.org/svn/Xpra/trunk@5499 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/man/xpra.1

@@ -520,13 +520,15 @@ Specifies the video encoders to try to load.
 By default, all of them are loaded, but one may want to specify
 a more restrictive list of encoders.
 Use the special value 'help' to get a list of options.
+Use the value 'none' to not load any video encoders.
 
 .TP
 \fB\-\-csc\-modules\fP=\fIMODULES\fP
 Specifies the colourspace conversion modules to try to load.
 By default, all of them are loaded, but one may want to specify
 a more restrictive list of modules.
 Use the special value 'help' to get a list of options.
+Use the value 'none' to not load any colourspace conversion modules.
 
 
 .SS Options for start, upgrade and attach

src/xpra/scripts/main.py

@@ -487,12 +487,18 @@ def enabled_str(v):
             if options.video_encoders=="help":
                 print("the following video encoders are available: %s" % ", ".join(get_DEFAULT_VIDEO_ENCODERS()))
                 sys.exit(0)
-            options.video_encoders = [x.strip() for x in options.video_encoders.split(",")]
+            elif options.video_encoders=="none":
+                options.video_encoders = []
+            else:
+                options.video_encoders = [x.strip() for x in options.video_encoders.split(",")]
         if type(options.csc_modules)==str:
             if options.csc_modules=="help":
                 print("the following csc modules are available: %s" % ", ".join(get_DEFAULT_CSC_MODULES()))
                 sys.exit(0)
-            options.csc_modules = [x.strip() for x in options.csc_modules.split(",")]
+            elif options.csc_modules=="none":
+                options.csc_modules = []
+            else:
+                options.csc_modules = [x.strip() for x in options.csc_modules.split(",")]
 
     #special handling for URL mode:
     #xpra attach xpra://[mode:]host:port/?param1=value1&param2=value2