Video get choppy(stutter) every 5 minutes.

System: Mac Pro 2013 , 8 core, 32gb ram, GPU AMD D700

OS: Mojave 10.14.6   

Wirecast Pro : 14.1.2

Camera: Sony A6400, Sony A73

Capture Device:  Blackmagic Ultra Studio Recorder for 1080 25p

                              Elgato CamLink 4k for 1080 50p

Canvas Size, Video Display Rate are matched accordingly to 25p and 50p video capture. Camera was set to the right shutter speed.

Live GPU Accelerated Icons are DISABLED

No drop frame reported in Wirecast and CPU usage is below 15% without recording and below 30% with recording.


Problem: Video will turn choppy (stutter) in the 'LIVE' window after 5-6 minutes. The choppiness will appear for about 2 minutes and then the motion will revert to normal again for another 5-6 minutes before it get choppy all over again. This happen in the 'LIVE' window even without any recording or streaming. 

Troubleshooting steps: we created a new user account, removed all USB connections, use only one monitor and the monitor was set to 1080p 50 hertz. We first tested with BM Ultra Studio Recorder for a 1080p25 capture and then the Camlink 4k for 1080p50 and the result for both were the same, choppy (stutter) video after every 5-6 minutes 

We then try capturing through Quicktime and Blackmagic Media Express and we were able to see smooth motion video on the screen and the recording. 

We then changed over to another Mac pro 2013 with the same specs to no avail, same result like the previous mac pro.

I have attached the stutter clip for your reference. I recorded in 720p50 to keep the file size down for the upload. As said, it happened regardless of whether we set it up for 720p50, 720p25, 1080p50 or 1080p25. 

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  • Hmm, Maybe I'm missing something but your "choppy" video plays perfectly smooth on my system. It's 720p50 and I can even jog through frame by frame and there are no dropped or duplicated frames.

    Michael Chiang said:
    Wirecast Pro : 14.1.2

     Wirecast 14.2 may have improved playback

    Test with a new document. 
    Blackmagic driver should be 11.6 for Mojave.
    If your camera is 25fps set Wirecast Preferences Video Display Rate to 25fps.

    It is possible under certain scenarios where the Live Broadcast Area is not accurate. Your recording does look good to me though.

  •  Sorry, I uploaded  the  wrong clip.😄  The one uploaded  earlier  was captured from the 5-6 min sequence..

      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 1 yr ago
      • Reported - view

      Michael Chiang I see a few duplicate/skipped frames in that one. It may not be the best image to determine the issue though. Perhaps shoot a close up of a clock with seconds or stop watch with hundredths of seconds.

      Please test in 14.2 only though.

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