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Audio/Video Drift in ScreenFlow recordings

Topic: Audio/Video Drift in ScreenFlow recordings

Dear all

I'm using ScreenFlow to record video lectures that combine PowerPoint screen recordings with a video overlay of me talking.

The problem is that the video and audio my narration gradually drift out of sync (video slower than audio). Initially, the video lags behind about 3 frames at 30FPS, i.e., about 100ms. During the recording, the offset increases by about 3 frames per 15 minutes. After a typical lecture of 45 minutes, video and audio are therefore off by 12 frames (400ms), which is very disturbing because the lip movement and audio no longer match at all.

My recording setup is as follows:

  • ScreenFlow 9.0.4
  • MacBook Pro, 15" late 2013 model attached to an Apple Thunderbolt display running macOS 10.15.5
  • Audio captured with M-Audio Air 192|6 USB audio interface, 48kHz sampling rate, directly connected to Mac without USB hub
  • Video connected with Logitech C925e USB webcam, directly attached to Mac without USB hub

I can reproduce the same problem using a different USB audio interface and USB camera:

  • Presonus StudioLive 12 USB mixer
  • iSight USB video camera that is built into the Apple Thunderbolt Display

The problem is also independent of the sample rate and can be reproduced at 44.1kHz and 48kHz.

To verify this is a ScreenFlow problem and not a problem of my hardware setup, I did test recordings with QuickTime and OBS. Neither QuickTime nor OBS show any noticeable video drift but only a constant offset of about 3 frames.

  1. https://www.dropbox.com/s/q5upoivqhpr1q2e/ScreenFlow-AV-Drift.screenflow.zip?dl=0
    ScreenFlow Recording 30 FPS, video: Logitech C925e @ 640x480, audio: M-Audio Air 192|6 @ 48kHz
  2. https://www.dropbox.com/s/2ckc23zus0dzfkc/ScreenFlow-AV-Drift.mp4?dl=0
    Same as above but exported as H264 in MP4 format
  3. https://www.dropbox.com/s/mrk31zfrv37x6ei/OBS-AV-Drift.mp4?dl=0
    Recording with OBS 25.0.8, video and audio same as above, recorded as H264 in MP4 format

In these test recordings I am recording myself making a hand clap every 15 minutes. This allows me to compare the audio peak and the frame in which my hands touch in the ScreenFlow timeline, or in Adobe Premiere for the recordings made with QuickTime and OBS. Watch for the hand claps around 0/15/30/45 minutes.

I would be grateful for any help in solving this problem.

Also, I would appreciate it if anybody could try to reproduce this problem using the hand clap test. Given that I can reproduce this problem with two different USB cameras / audio interface combinations I wonder how widespread this issue is.

Kind regards
 Christian
 

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    • CraigSModerator
    • Telestream Desktop Forum Moderator
    • CraigS
    • 5 mths ago
    • Reported - view
    Chris Kresser said:
    The audio/video are in sync in the timeline. I exported the video as an MP4 in 4k. Here is a link to the video. As you can see, the audio and video are out of sync right from the start. 

     Perhaps you can send us a link to the document so we can examine and do a test export on our systems.
     

    Chris Kresser said:
    it doesn't seem to be a capture/hardware issue, but something that is happening in the export.

     Given your description of the issue I'd agree. This is why we may need to see the document. We'd need to look at timeline vs export.

    Are you using one of our export presets unaltered? If not please test.
    Also test with an Apple ProRes preset to see if this is specific to x264 encoding.

    It's not clear what your export settings are. That might be part of the issue. We'd need that. A screenshot is best as people often leave out the details in their descriptions.

    Like
    • CraigS Thanks for your help. 

      Here is a link to the Screenflow document. 

      Here are the export settings I was using (custom):
       

      I just tried exporting with the ProRes 422 preset, and the sync issue is still there. You can see that video here

      Anything else I should try? I read in another post that you can set the fps for the timeline to 29.97. I didn't do that because I'm not sure how. 

      Like
      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 5 mths ago
      • Reported - view

      Chris Kresser 
      In the document I see a screen recording and the Camlink recording.
      In the timeline I only see the Camlink recording on Track 1 (top track).
      Frame Rate is 30fps.
      It looks out of sync (offset) in the timeline. The audio looks to be 6 frames ahead of the video at the start (measuring the audio distance from matching lip movement in the video).
      So it does look out of sync in the timeline.
       

      Like
    • CraigS Ok. What would you suggest as the next step for troubleshooting? 

      I just recorded a test using the built-in Macbook Pro FaceTime web cam, and the Shure MV7 mic. That looked good in both the timeline and export. 

      So, it seems the issue might be with using the Fuji X-S10 as an external camera via the Elgato Camlink 4k. Right now, the Camlink is plugged into a hub. I am going to try to connect it directly to the Macbook Pro and see if that helps. 

      Is anyone on the forum successfully using Camlink without any sync issues? 

      Like
    • CraigSModerator
    • Telestream Desktop Forum Moderator
    • CraigS
    • 5 mths ago
    • Reported - view
    Chris Kresser said:
    I read in another post that you can set the fps for the timeline to 29.97. I didn't do that because I'm not sure how. 

     It's not a preset option. But it seems you're describing something other than framerate sync drift.

      

    Like
    • CraigSModerator
    • Telestream Desktop Forum Moderator
    • CraigS
    • 5 mths ago
    • Reported - view
    Chris Kresser said:
    So, it seems the issue might be with using the Fuji X-S10 as an external camera via the Elgato Camlink 4k. Right now, the Camlink is plugged into a hub.

     Video and audio on different signal paths can have different latency. Hubs can impact that.
    The ideal is to send audio into the camera so they are on the same path.
    The Camlink into a hub into the computer may have more latency than audio going directly in.
    Audio on a separate path than video may be processed ahead of the video.
    Often times the fix is to slip the audio after it's recorded to match the video.
     

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    • CraigS Ok, thanks again. I'm pretty new to all of this, so I appreciate your help.

      It sounds like it would be better to plug my Shure MV7 directly into the Fuji camera, and/or plug my Rode VideoMic NTG directly into the camera, than running the MV7 into the computer (via hub or not) with USB? 

      I did some research and it does seem it's possible to connect the MV7 directly to the camera. 
       

      Like
    • CraigS  Ok, I recorded a new test with both the audio and video source set to Camlink 4k. The Shure MV7 is connected to my Fujifilm X-S10 via a 3.5mm TRS cable. There is a high-pitched noise in the audio that may be caused by bias voltage in the camera (according to this article on Shure's website). I just ordered an interface from Beachtek to address that issue.

      Other than that, it does seem that the audio/video are in better sync, though it may still be off a bit? What do you think? Here is the test

      Like
    • CraigS Hi Craig, wondering if you've had a chance to look at the new test video I posted in my last response? I just want to make sure I'm on the same track. Thanks. 

      Like
      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 4 mths ago
      • Reported - view

      Chris Kresser Looked at the video.  The sync looks good. The audio input certainly does have issues that sound like an input issue. An interface should help that.

      Like
    • CraigS Great! I got a Beachtek DXA Micro Pro. That fixed the audio issue. I think I might finally have it sorted, but can you check this exported MP4 and see if it looks fully synced to you? Thanks!

      Like
      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 4 mths ago
      • Reported - view

      Chris Kresser Looks very good. There's a small amount of latency but it's hard to notice.

      Like 1
    • CraigS Hooray! Thanks for your help in figuring this out. 

      Like
      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 4 mths ago
      • Reported - view

      Chris Kresser 👍 You're welcome of course.

      Like
  • CraigS said:
    Audio on a separate path than video may be processed ahead of the video. Often times the fix is to slip the audio after it's recorded to match the video.

     What does "slip the audio" mean? Can you direct me to a support article on how to do this?

    Like
    • CraigSModerator
    • Telestream Desktop Forum Moderator
    • CraigS
    • 5 mths ago
    • Reported - view
    Chris Kresser said:
     What does "slip the audio" mean?

     Detach the audio if it needs to be and then shift it until it's in sync. Sometimes that's referred to as slipping. We don't have an article specific to this as of yet. 

    Like
  • I am having similar issues with a Nikon Z 6II and Nikon Webcam Utiilty that I posted in a Nikon thread. 

    Audio drifts more and more over the length of the clip in Screenflow.

    Zoom is fine as is recording video through Chrome. Everything is in sync there. 

    Like
      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 5 mths ago
      • Reported - view

      Cameron Saemann ScreenFlow can't really be compacted to Zoom or Chrome. You could try in Quicktime.

      You don't mention ScreenFlow version, macOS, Mac hardware signal paths so I can't comment on that. For troubleshooting, you always need to provide information so support can reproduce your exact workflow. Otherwise, we can only give a general response to a general comment. Sorry about that.

      You posted more information in the other thread. There's no need to double post especially since one doesn't contain all the details. Sorry but it's best to post once only with details.

      Like
    • CraigS Apologies! I realized this would have been a better thread to post in, but it was after I'd already I'd hit the Nikon one. 

      Like
      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 4 mths ago
      • Reported - view

      Cameron Saemann We'll continue in the other thread though given the ongoing discussion we have there.

      Like
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