# smooth streaming: is system-bitrate required attribute **URL:** \ **Category:** Wowza Streaming Engine\ **Created:** [September 12, 2012, 10:50am UTC](https://community.wowza.com/t/smooth-streaming-is-system-bitrate-required-attribute/39170 "2012-09-12T10:50:50Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Mike\_Phillips](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mike\_Phillips](https://community.wowza.com/u/Mike_Phillips)\ **Post date:** [September 12, 2012, 10:50am UTC](https://community.wowza.com/t/smooth-streaming-is-system-bitrate-required-attribute/39170/1 "2012-09-12T10:50:50Z")
This thread [https://www.wowza.com/docs/how-to-set-up-video-on-demand-streaming#ABR](https://www.wowza.com/docs/how-to-set-up-video-on-demand-streaming#ABR) mentions that the system-bitrate is calculated automatically. Since it is calculated automatically I don’t want to specify it. I tried removing the attribute but the streams do not play without the system-bitrate being present. Is this a required attribute? The thread also mentioned setting smoothStreamingUseSMILBitrates true Boolean in Application.xml HTTPStreams/Properties. This section does not exist. I tried adding it and setting the value to false. This had no effect I still had to have something for system-bitrate value. I want to dynamically generate a .smil file and don’t want to do calculations to specify the system-bitrate value. ---
**Author:** ![Richard\_Lanham](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard\_Lanham](https://community.wowza.com/u/Richard_Lanham)\ **Post date:** [September 12, 2012, 8:46pm UTC](https://community.wowza.com/t/smooth-streaming-is-system-bitrate-required-attribute/39170/2 "2012-09-12T20:46:56Z")
I think Silverlight calculates actual bitrate of the streams. So you should be able use any value for system-bitrate, and do not include that Property in that case. Richard ---
**Author:** ![Randall\_Auriemma](https://avatars.discourse-cdn.com/v4/letter/r/85e7bf/32.png) [@Randall\_Auriemma](https://community.wowza.com/u/Randall_Auriemma)\ **Post date:** [September 16, 2012, 7:27am UTC](https://community.wowza.com/t/smooth-streaming-is-system-bitrate-required-attribute/39170/3 "2012-09-16T07:27:52Z")
meprospero, In my previous testing with WMS 3.0.5 I also noticed the smoothStreamingUseSMILBitrates had no effect when added to either HTTPStream(er/s) element in Application.xml. However in my case, changing the system-bitrate in the smil to invalid values, such as “1, 2, and 3” etc… cause different behavior than with accurate bitrates. But, I think I had faulty media in my tests. I will investigate and get back to you when I have a useful suggestion. Could you PM me with a download link to your media with the overlays? It would help with testing. If not, don’t worry about it. Thanks. ---
**Author:** ![Mike\_Phillips](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mike\_Phillips](https://community.wowza.com/u/Mike_Phillips)\ **Post date:** [September 14, 2012, 2:05pm UTC](https://community.wowza.com/t/smooth-streaming-is-system-bitrate-required-attribute/39170/4 "2012-09-14T14:05:56Z")
> I think Silverlight calculates actual bitrate of the streams. So you should be able use any value for system-bitrate, and do not include that Property in that case. > > Richard From article: [https://www.wowza.com/docs/how-to-set-up-video-on-demand-streaming#ABR](https://www.wowza.com/docs/how-to-set-up-video-on-demand-streaming#ABR) “Note: By default Silverlight Smooth Streaming will calculate video and audio bitrates for the manifest data on-the-fly by inspecting the file. If you want to instruct Wowza Server to use the bitrates in the SMIL file, add the following property to the HTTPStreams/Properties container in [install-dir]/conf/[application]/Application.xml (be sure to get the correct container - there are several in Application.xml). When running in this mode, Wowza will assume the video and audio system-bitrate values are for the video and audio data only:” This setting has no effect. It appears the system-bitrate is always used. I have found the easiest way to view the switching is to burn a graphics overlay with the bit rate of the video. # the src filenames show what bit rate the files are # On a high speed connection we see 500 followed by 1500 ending with the playback of the 20000 # If I swap the values and assign incorrect bit rates to the videos I see that the system is using my system-bitrate settings # On a high speed connection we see 20000 followed by 750 ending with the playback of the 500 to the end This tells me the system-bitrate is always used. I am required to have a clear understanding if it is an option to not define the system-bitrate and depend on the wowza server calculating the values correctly on the fly.