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Thread: smooth streaming: is system-bitrate required attribute

  1. #1

    Default smooth streaming: is system-bitrate required attribute

    This thread http://www.wowza.com/forums/content.php?35#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
    <Property>
    <Name>smoothStreamingUseSMILBitrates</Name>
    <Value>true</Value>
    <Type>Boolean</Type>
    </Property>

    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.

  2. #2
    Join Date
    Dec 2007
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    Default

    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

  3. #3

    Default

    Quote Originally Posted by rrlanham View Post
    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: http://www.wowza.com/forums/content.php?35#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 <Properties> container in [install-dir]/conf/[application]/Application.xml (be sure to get the correct <Properties> 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
    <video src="mp4:Toronto00500_DeInt.mp4" system-bitrate="635000"/>
    <video src="mp4:Toronto00750_DeInt.mp4" system-bitrate="885000"/>
    <video src="mp4:Toronto01000_DeInt.mp4" system-bitrate="1134000"/>
    <video src="mp4:Toronto01500_DeInt.mp4" system-bitrate="1637000"/>
    <video src="mp4:Toronto20000_DeInt.mp4" system-bitrate="11800000"/>

    # 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
    <video src="mp4:Toronto00500_DeInt.mp4" system-bitrate="11800000"/>
    <video src="mp4:Toronto00750_DeInt.mp4" system-bitrate="1637000"/>
    <video src="mp4:Toronto01000_DeInt.mp4" system-bitrate="1134000"/>
    <video src="mp4:Toronto01500_DeInt.mp4" system-bitrate="885000"/>
    <video src="mp4:Toronto20000_DeInt.mp4" system-bitrate="635000"/>

    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.

  4. #4

    Default

    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.

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