Solutions

With Silverlight and video on demand there is a delay of about 15 seconds when you jump back within the video.

Solutions ID:    KB3883
Version:    1.0
Status:    Published
Published date:    07/12/2010
 

Problem Description

When using Windows Media player it is working without any issues.

A url which exhibits this issue is the following one:

http://www.microsoft.com/emea/spotlight/sessionh.aspx?videoid=668

On a slow internet link without a proxy  you will see the same problem. With a fast internet link the problem is not there.Here are a few observations observed when comparing a packet trace for a direct connection and one when going through a proxy.

direct connection capture : the client is setting accelbw to a maximum value for 20sec duration and server responds with 3.5Mbps for 20sec duration

Client going via a proxy : 1Mbps accelbw for 10sec duration.


The difference in behavior and perceived better experience when going direct could be attributed to this.

Resolution

Setting bypass_cache(yes) and setting max-fast-bandwidth on the blue coat to 3500kbps improves the performance to a certain degree. One option is to modify the Silverlight plugin configuration and somehow force it to use a ‘connection-speed’ higher than 1Mbps. On WM player, this is usually at Tools->Options->Performance->Connection speed->choose your connection speed.There does not appear to be a way to modify this on the silverlight plugin. It's quite likely the silverlight plugin uses packet-pair bandwidth estimation. The SG does not support this since we only support 1.0 version of WM-HTTP protocol, and the plugin uses 1.1 version to server.


One other option to consider is to use smooth streaming (adaptive streaming) which is available on windows 2008 and iis 7.0. This does not use wm-http but http so should be easily cacheable on the sgos. It basically splits the strip into multiple objects which can be encoded at different bit rates. More information can be found here.


http://alexzambelli.com/blog/2009/02/04/the-birth-of-smooth-streaming/


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