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Thread: Framerate wrong using CUDA transcoder

  1. #1
    Join Date
    Jan 2012
    Posts
    1

    Default Framerate wrong using CUDA transcoder

    Yesterday we installed, for the first time, trial version of Wowza Media Server 3.0.3 as we want to test transcoding capabilites for live streams before commiting to use it in our project.
    Thanks to excellent documentation available on this web site we managed to install the server on a Windows 2008R2 server and optimize it according to your recommendation (64-bit Java server mode, increased heap, etc).

    We successfully created a live stream by using Transcoder AddOn from an IPTV multicast UDP MPEG-TS source (MPEG-2 video, Layer2 audio, framerate:25fps). Output stream is H.264 main profile with AAC audio. When using default transcoder Wowza generates output stream with the same frame rate as source (25fps). However, after switching to CUDA framerate of transcoded stream is 29.97 !?

    To confirm this we created two Encode templates (one named "full" and the other "cuda") for the same source stream so that Wowza generates two streams one with default transcoder and the other with CUDA. All other parameters for both transcoder encode templates are the same. We can see in Wowza log that CUDA encoder generates stream with 29.97fps and default transcoder generates 25fps. See log below:

    ...
    2012-01-11	14:28:25	CET	encoder-video-start	transcoder	INFO	200	IPTV1.stream	{name:"cuda", bitrate:1200000, codec:H264, profile:77, level:31, frameSize:1024x576, displaySize:1024x576, frameRate:29.97}	-	-	-	3.879	-	-	-	-	-	-	-	-	-	-	-	-	-
    ...
    2012-01-11	14:28:25	CET	encoder-video-start	transcoder	INFO	200	IPTV1.stream	{name:"full", bitrate:1200000, codec:H264, profile:77, level:31, frameSize:1024x576, displaySize:1024x576, frameRate:25.0}	-	-	-	4.082	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
    ...
    We also confirmed with rtmpdump that CUDA transcoder generates stream with the wrong framerate (29.97 instead of 25).

    We beleive that this could be a bug as the only parameter we changed between two encoding templates is the type of transcoder. As CUDA hardware we use Quadro 4000 card with the latest NVidia driver.

    Visually both streams look almost the same except that the stream that CUDA generates seems to stutter more from time to time. Could that be due to framerate change?

    We would really like to use CUDA to be able to decode as many streams on one server as possible (streams are in PAL resolution 720x576).

    Is there any way to force transcoder to use certain framerate? Is this really a bug?

  2. #2

    Default

    Hi nitnit,

    Thanks for reporting this. It's being looked into, and we will report back with more info, when available.

  3. #3
    Join Date
    Feb 2011
    Posts
    18

    Default

    Hello, just wanted to let you know we haven't forgotten this post - just trying to make some room in QA to try and reproduce / characterize a little better. We should have a response at the beginning of next week. If you would prefer to track this in a ticket, just email support@wowza.com and reference this forum thread.

    Cheers, Adam...

  4. #4
    Join Date
    Feb 2011
    Posts
    18

    Default

    This problem is addressed in Wowza 3.0.5. Please upgrade your Wowza version and this will then work as needed.

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