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Thread: HLS livestream multistream switching problem

  1. #1
    Join Date
    Nov 2009
    Posts
    25

    Default HLS livestream multistream switching problem

    hello,

    I'm running wowza HLS livestream with 3 different qualities that I'm pulling from CDN.

    With iOS devices, switching of qualities works just fine.
    But there is a problem with smart TV devices (LG). Here is what I've found out:

    Live stream starts to play. After cca. 20 seconds when quality should change from lower to higher, the stream simply freezes and it doesn't continue to play.
    The problem is that somehow player wants to access the same filename (.ts) on stream to which he is switching, and if that stream doesn't have that file it simply refuses to play, example:

    This is how it looks the playlist from 3 different qualities:

    Low:
    media_859.ts?wowzasessionid=490125569
    media_860.ts?wowzasessionid=490125569
    media_861.ts?wowzasessionid=490125569
    Medium:
    media_858.ts?wowzasessionid=490125569
    media_859.ts?wowzasessionid=490125569
    media_860.ts?wowzasessionid=490125569
    High:
    media_855.ts?wowzasessionid=966022614
    media_856.ts?wowzasessionid=966022614
    media_857.ts?wowzasessionid=966022614
    As you can see the sequence numbers in each stream do not match. The problem is solved by restarting wowza, and the player works fine

    This is how it looks like after restart, which is OK:

    Low:
    media_3.ts?wowzasessionid=945643668
    media_4.ts?wowzasessionid=945643668
    media_5.ts?wowzasessionid=945643668
    Medium:
    media_3.ts?wowzasessionid=246305015
    media_4.ts?wowzasessionid=246305015
    media_5.ts?wowzasessionid=246305015
    High:
    media_3.ts?wowzasessionid=1410221705
    media_4.ts?wowzasessionid=1410221705
    media_5.ts?wowzasessionid=1410221705
    After about 30min of running wowza, the problem is present again.
    Can you please tell me what is causing this unusual behaviour?

    Thank you

  2. #2

    Default

    As a place to start, you can enable debugging to test multi-bitrate key frame alignment:
    How to debug encoder multi-bitrate key frame alignment

    Salvadore

  3. #3
    Join Date
    Nov 2009
    Posts
    25

    Default

    thanks for the link.
    Now that i know that frames are not alined and that using "chunkBreakOnPTS" parameter does not solve the problem, anybody have any other idea why this is happening?
    The most interesting thing here is that when sequence numbers are different for each stream, i download a video chank from each stream and they are a match although the sequence numbers on each stream are totally different!

    Anyone here care to explain this?
    thanks

  4. #4

    Default

    The only way to guarantee alignment of the key frames is to pull the highest quality stream from the CDN through the Wowza Transcoder AddOn.

    From that source stream you can create a set of key frame aligned renditions for Adaptive bit rate switching.

    Salvadore

  5. #5
    Join Date
    Nov 2009
    Posts
    25

    Default

    Using Wowza Transcoder AddOn is the only way you can get this to work properly? There is really no other way?

  6. #6

    Default

    There is no other way within Wowza to sort out the key frame mis-alignment.

    Salvadore

  7. #7
    Join Date
    Nov 2009
    Posts
    25

    Default

    is it possible to get a trial version of the add-on? I would like to test this 1st.

  8. #8
    Join Date
    Jun 2012
    Posts
    722

    Default

    The Transcoder Addon is available when using a Wowza trial license.
    Here is the direct URL for the Trial license request: http://www.wowza.com/pricing/trial

    Zoran

  9. #9
    Join Date
    Nov 2009
    Posts
    25

    Default

    btw, I came across this article:
    http://www.wowza.com/forums/content....onitorAdvanced

    Isn't this exactly what would solve my problem? resetting the stream when multistream would get out of sync?

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