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How to reduce the live delay time with hls-live?

Feb 14, 2012 5:00 PM

I'm noticing a 13-16 second delay with live streams to iOS devices. Is there any way to improve this delay time by modifying the Event.xml parameters or the Apache hlshttp_module parameters in httpd.conf?


Thank you for any tips.

  • Currently Being Moderated
    Feb 14, 2012 11:24 PM   in reply to bobakb

    Apples HLS spec for client says that client will play the 3rd last segment in the playlist. So you are bound to get the latency of 3*media-file-duration. In FMS, we set media file duration to be 8000 ms (8 sec).. You can try to reduce it to 4000 or 2000 either httpd.conf, or event.xml, application.xml


    However, you may read -media-file-duration/ for knowing the implications (pros-cons) of this..

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    Feb 15, 2012 10:23 AM   in reply to bobakb

    No its not same - it needs to same or multiple of FragmentDuration. I think article which Nitin has pointed out in his previous post should help you understand things better,

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    Feb 16, 2012 7:39 PM   in reply to bobakb

    I have the same problem,..the delay around 8~12 seconds,..


    I changed the keyframe frequency to 1 second in Flash Media Live Endcoder's video setting,..

    and the "httpd.conf" config file in "Flash Media Server4.5\Apache2.2\conf",..

    <IfModule hlshttp_module>

    <Location /hls-live>


         HLSMediaFileDuration 2000


    the other config is default,..can't solve this problem,..anyone can help us>??

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    Feb 16, 2012 8:29 PM   in reply to lamfungjerry

    Just request the m3u8 from browser and download it.. This is plan text file. Just check that your target duration is set to 2 after the httpd.conf change. If not, you have either not restarted the apache server after the change or Event.xml or Application.xml is overridign this vlaue..


    Regarding delay.. I am not sure you can get better than this on Http streaming.. I hope you read the article and understands why all Http streaming protocols suffers from delay..

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    Feb 16, 2012 10:19 PM   in reply to Nitin Goel

    Nitin Goel, thanks for your help!

    I have readed your link in previous post, I have a little bit understands why have delay in the http streaming protocols

    But the delay is around ten more second, I think it must  somhavee problem in my setting.


    After I restart the server after change the "httpd.conf" file and check m3u8 's xml, the duration is 0.


    I have find the 2 Event.xml file in "Flash Media Server 4.5" folder


         I don't know where is this file's duration setting.






    And I find the Application.xml in "application\livepkgr"

    the only 1 setting is




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  • Currently Being Moderated
    Feb 19, 2012 10:37 PM   in reply to lamfungjerry

    In httpd.conf , you can edit HLSMediaFileDuration .. it is specified in milliseconds


    <Location /hls-live>

        HLSHttpStreamingEnabled true

        HttpStreamingLiveEventPath "../applications"

        HttpStreamingContentPath "../applications"

        HLSMediaFileDuration 8000

        HLSSlidingWindowLength 6

        HLSFmsDirPath ".."

        HLSM3U8MaxAge 2

        HLSTSSegmentMaxAge -1

        Options -Indexes FollowSymLinks



    In Event.xml


    You can add








    <HLS> tag has to be sibling tag of the <Recording>


    Same applies to Application.xml


    Read Application-level and event-level configurations for live HLS @ f23d103e5512e08f3a338-8000.html#WS8c0554f47ab8e40d-323660bc131f49feddc -7fff

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    Feb 25, 2012 12:23 PM   in reply to Nitin Goel

    Am I correct in assuming that Event.xml overrides Application.xml and httpd.conf, and Application.xml overrides httpd.conf?  Then httpd.conf values are used if they are not specified in the Application or event?

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    Feb 27, 2012 9:55 AM   in reply to BrandonMX84

    Yes you are right in your assumptions.

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