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Thread: Degradation in transcoder quality after upgrading to 4.1.1

  1. #1
    Join Date
    Apr 2014

    Default Degradation in transcoder quality after upgrading to 4.1.1


    We recently upgraded Wowza Streaming Engine to 4.1.1 from 4.0.4 and we are seeing degradation in video quality and blockiness in the video after upgrade.

    We have this setup where we are running Wowza on AWS ec2 with GPU enabled boxes, and we are pushing RTSP/RTP stream to Wowza and publishing RTMP to akamai from wowza.

    I downgraded after upgrading and I couldn't see the issue, but with upgrade without any changes on the RTSP side we see the issues.

    Also tried disabling the GPU on the box to make sure that its not the issue with drivers and i can still see lower quality with the same template.

    Here is the transcoder template we are using :

    Let me know if you need more information on this.

    Last edited by anupam; 01-30-2015 at 09:59 PM.

  2. #2



    I think the most efficient course of action would be to open a ticket with support.

    Please send a zipped copy of the following folders:

    Please also include a screenshot of your exact live encoder settings. As well as a sample recording of a problematic incoming stream. And a link to this thread as a reference to

    Kind regards,

    Last edited by salvadore; 01-31-2015 at 06:32 AM. Reason: added support email address

  3. #3
    Join Date
    Sep 2011


    This issue will now be handled in the ticket you have created (116913).


  4. #4
    Join Date
    Feb 2015


    Confirmed here too -- WSE encoder add-on in 4.1.1 output definitely suffers, we hypothesize, from poor configuration of several important parameters in the MainConcept encoder.

    The manifestation of the issues here appears as a visible 'pumping' or 'ramping' of fine detail within a GOP; the I frame tends to get more aggressively quantized (for the reasons mentioned later) more than the B or P picture MB's which come after the I frame. The visual result is a hugely obvious keyframe introduction at the beginning of each GOP, followed by a slow increase in fine detail throughout the rest of the GOP's B and P pictures/frames.

    In short, analysis of the problem here at our shop suggests that one or all of qcomp, rc-lookahead, vbv-maxrate, and vbv-bufsize are currently naively configured by WSE 4.1.1 when initializing the MainConcept encoder. We dug around in the encoder detailed output logs, but were unable to find any useful parameters to adjust. As best we can tell, the parameters that need tweaking aren't exposed via the "vaapi" config parameters available in the transcoder xml config file.
    So, we ran, not walked, back to 4.0.x in the mean time.

    Good thing us users excel at q/a!

    Last edited by tkapela; 02-11-2015 at 09:13 AM.

  5. #5
    Join Date
    Jun 2011


    Anyone seeing this issue should update to version 4.1.2 or later. Check this page for information on the most recent builds.


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