Knowledgebase
SECRET PRO TIP: How to make Screen Sharing faster (with a little hack)
Posted by Robert Strobl on 12 June 2015 10:09 AM

We have two major improvements to AppShare in version 4.3.7 - however they are not yet connected to the UI of the platform so they have to be set via the config file. Connection to the UI is planned for an upcoming version. Once set, the parameters don’t have to be edited again until the plug-in is reinstalled.

This article tells you how to edit the Config file:
http://support.digitalsamba.com/index.php?/Knowledgebase/Article/View/247/0/reducing-quality-of-screen-share-to-save-bandwidth---experimental

I suggest not changing any of the values in this article, instead focus on the following two undocumented settings.

Note:
Application Sharing must not be running when you are editing the file. If it is running, make sure to exit or quit the pogram, and then relaunch it after you have edited the config file.

1. Scaling down resolution

Scaling down hugely reduces your use of bandwidth and thereby increases the speed of screen updates.

There is also an additional benefit. The maximum screen resolution we support is 4096px on any length, or combination of length of multiple screens. As screen resolutions get higher, or as users use multiple screens, you can now use this option to scale down your screen and share high-resolution screens or multiple desktops.

  1. install new appshare via the Flex UI
  2. before running it, open Application_Sharing.cfg
  3. find the parameter ScaleRatio = 1.0
  4. set it lower than 1.0 to scale down the image
  5. save Application_Sharing.cfg
  6. run appshare as you normally would in OnSync

Note:
In point 4, it should be scaled down so that the biggest screen dimension is less than 4096. For example, if the screen is 8192x6144, then the ScaleRatio should be less than 0.5.

Try setting this to 0.5 for example. You'll see much better performance at a minimal loss of quality.

2. Choosing your screen codec

This version introduces 2 new screen codecs for much improved screensharing performance.

It is possible to choose the following codecs by modifying codecID parameter in Application_Sharing.cfg:

DIGITAL_SAMBA_SCREEN_VIDEO - our old codec, current default setting.
DIGITAL_SAMBA_SORENSON_SPARK - For high motion sharing, best used if lots of videos are shared. When this codec is selected it is possible to alter one more parameter in Application_Sharing.cfg:
Bitrate=500000
A lower value will dynamically reduce quality as motion on screen increases. With higher values these reductions will be less visible but more bandwidth will be consumed.
DIGITAL_SAMBA_SCREEN_VIDEO_2 - More efficient screen codec than the one we previously used. Eventually this will become the default codec. I recommend setting to this one but bearing in mind that this is pre-official release, so unexpected issues may occur.

Note:
We are aware of low framerate issues with the DIGITAL_SAMBA_SORENSON_SPARK implementation in the 4.3.7 release, we will work to improve these before officially announcing the improved screen sharing features.

These are very exciting additions to our platform. Please let us know if you have any questions. And please rememeber, this is a pre-release. If you want to get back to default settings because you are getting unexpected performance, uninstall the screenshare app, then re-install it.

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