Need help with audio drifting out of sync
Hi Screenflow community,
• Computer hardware including screen size: Late 2015 iMac Retina 5k 27-inch. 4 GHz Quad-Core Intel Core i7. 24 GB 1867 Mhz DDR3 Ram, 500GB SSD, AMD Radeon R9 M395X 4GB GPU. Facetime HD Camera.
• OS version 10.15.1 macOS Catalina
• ScreenFlow version: Recorded video with latest version of 8. Upgraded to 9 after recording.
• External devices: Rode Podcaster connected via USB.
• Free hard drive space: 77.4 GB
• Number of Monitors: 1
• Recording settings: Record Desktop from iMac. Record Video from FaceTime HD Camera (Built-In) Format 640x480. Record Audio from RODE Podcaster v2 (Audio Sample Rate 96Khz)
• What you are recording: Google Slides presentation in Google Chrome
• Exported file: https://drive.google.com/file/d/1FbPy0pXK43AdcWj9gb8Dp4QMY0wvHEy1/view?usp=sharing
I'm using a late 2015 iMac Facetime HD camera, Rode Podcaster microphone, and the program Screenflow to record a 1 hour video presentation. For the first 20 minutes or so of the video the audio of me talking is in sync with the Facetime HD webcam footage. But slowly the audio begins to drift and falls out of sync with the Facetime HD webcam footage.
When I run the video file through ffmpeg with this command: "ffmpeg -y -i shopify_vsl_2.mp4 -af 'aresample=async=1000' -movflags faststart -r 30 -vsync vfr -f mp4 shopify_vsl_2_cfr.mp4" and force a constant frame rate the audio and webcam footage stay in sync much longer--but do still end up drifting.
The main thing that command does is force a constant frame rate of 30 frames per second in the footage and it drops duplicate frames.
My hunch is that the root of the problem is the Facetime HD camera does not maintain a constant frame rate but has a variable frame rate that changes depending on lighting and other factors. Other hypotheses are that the Rode Podcaster's audio sample rate (96Khz) isn't what Screenflow expects (Screenflow exported mp4s look to have an audio sample rate of 44.1Khz). I tried downsampling the audio to 44.1Khz in Audacity and adding it back in Screenflow and that made the audio syncing issues worse. I tried downsampling the audio to 48Khz in Audacity too but I was unable to do so because when I opened the audio file in audacity it registered as 48Khz already (even though in Audio MIDI Setup the Rode Podcaster input format was set to 96Khz when I recorded).
Does anyone have any recommendations on how to eliminate audio drifting out of sync when recording videos with Screenflow?
Correction to my previous post which had a typo. I am using
Secreenflow Version 9.0.6 (31673) (not 9.0.8) and Big Sur v.11.1 and the audio and video in Screenflow are out of sync (by different amounts throughout the recording).
@Craig S. Please release the version of Screenflow ASAP. I already have 18 hours of recorded lectures (plus editing time) to redo because of this problem, and another 6 hours to record this week. I'm considering switching to other software (Windows) if this isn't fixed soon. Big Sur was released last fall and this should have been fixed by Telestream already if the problem is really related to compatibility with the Mac OS (which was available to software developers long before released to me)..
If you have a Beta version of Screenflow 9.0.7 I would gladly use that until the official version is pushed out. The screen flow version I purchased and have now is not really useable and students complain it's distracting to be out of sync.
Thank you in advance for any help,
Followup to this problem / thread.
I was able to find an older Mac (Mac mini 2018 6-core intel) in the lab that had not yet been upgraded to macOS Big Sur and was running Catalina v10.15.7. I installed the current version of Screenflow version from the App Store (v9.0.6). I used the same hardware (Apogee Mic, Logitech C920 cam, as mentioned above when I noticed the problem on MacBook Pro) as I was using before and connected it directly to the Mac mini ports (no extension cables used). I conducted a clap test to see if there was still a sync problem between the video and audio.
Note - this test (and based on all the other tests described above) was designed to isolate if the audio-video sync problem in ScreenFlow is due to BigSur and ScreenFlow v9.0.6.
Results of the test were that there is still a sync problem between Catalina v. 10.15.7 and ScreenFlow v9.0.6, and the problem is not specific to BigSur. Sync offset was variable throughout the recording. However, in looking up the release date info for ScreenFlow v9.0.6 it appears it was released when the M1 processor Macs were released (~Nov. 17, 2020). Screenflow v9.0.6 was released on Dec. 17, 2020 for M1 Mac compatability. In looking at the all the recordings I've made weekly since July, the sync problem between audio and video only started occurring for me after the Screenflow 9.0.6 release in Dec. 2020.
The conclusion - the sync problem between audio and video in Screenflow 9.0.6 appears to have been introduced in the upgrade to this version. It doesn't matter if you running macOS Catalina or BigSur - you may have this sync problem. There is no way around this problem until this bug is fixed by Telestream unless the older v9.0.5 of screen flow is made available to us (which I would welcome). It appears they did not test the 9.0.6 version on Intel Macs well enough before releasing it. Pity. Current version of ScreenFlow 9.0.6 is useless on my Intel Mac if including a 'talking head' (which is why many of us buy screen flow rather than recording audio directly in powerpoint). I don't know if the Sync problem occurs on an M1 processor Mac.
Thanks Craig. This is great that old versions are available as a temporary fix (hopefully) to my problem. I've downloaded and installed v9.0.5, but it's the demo version. I bought my original version (earlier last year) through the Apple App Store. How do I transfer my license from the App Store version to 9.0.5 that I downloaded?
I didn't see instructions for this on the web page, or an option to transfer a license when I select 'ScreenFlow -> Buy ScreenFlow....' in the menu.
The App Store doesn't use serial numbers so there's no viable serial number for our web store version. Unfortunately the Mac App Store doesn't make available previous versions (Apple's policy not ours). If you would like to go from the App Store version to our Serial version contact DesktopSales with a screenshot showing the purchase in the Mac App Store and explain you need to cross grade to move back to 9.0.5 due to the 9.0.6 sync issue.
The Mac App Store and our webstore license are not interchangeable given the different systems so you have to move from one to the other long term.
A final note here for anyone else having this problem. I thought I share this since it took me literally days to figure the problem out with help from Telestream.
I downgraded my installation of Screenflow 9.0.6 to 9.0.5 using the information in this thread. After installing and recording in 9.0.5 I had no problems. The audio and video stayed in sync over a 80 minute recording with clap tests. I also opened the saved file I made in 9.0.5 in 9.0.6 to see if the audio/video were still in sync and they were. So the problem seems to be in the recording procedure/capture in 9.0.6, not in playback.
Small side note: the "File-> Save As" option did not work in the downgraded v9.0.5 I used, but this is easy to work around. We'll see soon if the new version 9.0.7 fixes this problem when it's released. You also won't be able to see templates saved in a newer version from within Screenflow.
Just a reminder - hardware used is:
16" MB Pro (2020), Logitech C920 camera, Apogee HypMic, Mac OS BigSur.
Thanks for your help CraigS.
Todd Ehlers said:
Thanks for your help CraigS.
You're welcome. Getting the 9.0.7 fix ready. Unless on Big Sur 9.0.5 is best to stick with and if it works on Big Sur for what you might need keep using 9.0.5. 9.0.6 is a must for Apple Silicon only. 9.0.7 will be the universal fix (only days away).
One "cheat" that might work for those on 9.0.6 is trying to do a slight speed change to line up video and audio. Granted it's a bit of testing to get that to line up. It's a thing to try if you have to salvage a project.
Hi CraigS just reporting that 9.0.7 has not fixed my audio lag, so I downgraded to 9.05 and are still dealing with the same audio lag issue.
My hardware is a high specced 2019 15" MBP, Canon EOS R6, Rode Video NTG, macOS 11.2.3.
In Screenflow my framerate is set to 25 on both timeline and desktop. I believe the Rode Video NTG is locked to 48Khz, and I can't drop this to 44.4Khz in Apple's Audio MIDI Setup.
Understanding that this is a complex issue to get over, any suggestions given that I've read a tried completing all the suggestions in this thread?
Oliver Roberts said:
9.0.7 has not fixed my audio lag
Is it a constant offset or drift.
If it's a constant offset you need to compensate by shifting one or the other in the timeline. Devices on different signal paths (camera vs USB mic) may have different latency.
As previously noted 9.0.5 should only be used if you are not on Big Sur. 9.0.5 has issues on Big Sur that were fixed in 9.0.7.
Please only test using 9.0.7.