Video downloaded from TikTok, crackling and Volume Changes

I tried to import some Videos I downloaded from TikTok into Fcpx.
When I playback those Videos in the timeline I hear crackling noises and constant huge volume change. 
Does anyone know the reason? The timeline audio is set to 48khz, TikTok-audio from video is 44khz.
Is there any solution?

When you press the spacebar and play the video using Finder's "Quick Look" feature, does it play normally? Or does that play OK and the problem only happens after importing to FCP?

Thanks for your help. Quicktime playback is fine - it only happens when I import the clips and try to play them in the timeline

When I convert Audio with Video passthrough in FFworks, there are no issues. Still strange, why music files in 44khz are no issue at all, but those videofiles are a problem..

I've never used TikTok before, but I just signed up and downloaded on my Mac a video using the below procedure. That video worked fine in FCP 10.6.5 on MacOS Ventura 13.3.1 on an M1 Ultra. 

Various video capture apps can produce different formats. Some of those are not standardized and may not work on some NLEs. My first suggestion is use the procedure and web site stated in the below tutorial. If that does not work, state the following information:

- The version of FCP you are using
- The version of MacOS
- The year and model of Mac you have
- The codec information of the captured video. Play the video in Qucktime Player, do CMD+I, spin down the disclosure triangle for "video details", then post the information for "General" and "video details".

TikTok download procedure on Macs and Apple devices:

Thanks for all your help joema!
Unfortunately the download-website you mention is not an option for me, as I need to show the watermark of the channel in the video (for legal reasons) when showing it on television.
So I usually just right click the video in the browser on tiktok and select "download".

To be honest, my system is VERY old, I am waiting for an m3 mac studio or mac pro right now to update.

MacBook Pro (Retina, Mid 2012)
Catalina 10.15.7 (19H2026)
FCPX 10.5.4

On Catalina, I dont get too much information in Quicktime and there is no disclosure triangle and categories, but heres the info from MediaInfo:

GeneralFormat : MPEG-4Format profile : Base MediaCodec ID : isom (isom/iso2/avc1/mp41)File size : 20.4 MiBDuration : 2 min 12 sOverall bit rate : 1 293 kb/sFrame rate : 30.000 FPSencoder : Lavf58.45.100VideoID : 1Format : AVCFormat/Info : Advanced Video CodecFormat profile : High@L3.1Format settings : CABAC / 5 Ref FramesFormat settings, CABAC : YesFormat settings, Reference frames : 5 framesCodec ID : avc1Codec ID/Info : Advanced Video CodingDuration : 2 min 12 sBit rate : 1 256 kb/sWidth : 576 pixelsHeight : 1 024 pixelsDisplay aspect ratio : 0.562Frame rate mode : ConstantFrame rate : 30.000 FPSColor space : YUVChroma subsampling : 4:2:0Bit depth : 8 bitsScan type : ProgressiveBits/(Pixel*Frame) : 0.071Stream size : 19.8 MiB (97%)Color range : LimitedColor primaries : BT.709Transfer characteristics : BT.709Matrix coefficients : BT.709Codec configuration box : avcCAudioID : 2Format : AAC LC SBR PSFormat/Info : Advanced Audio Codec Low Complexity with Spectral Band Replication and Parametric StereoCommercial name : HE-AACv2Format settings : NBCCodec ID : mp4a-40-29Duration : 2 min 12 sDuration_LastFrame : -3 msBit rate mode : ConstantBit rate : 32.0 kb/sChannel(s) : 2 channelsChannel layout : MSampling rate : 44.1 kHzFrame rate : 21.533 FPS (2048 SPF)Compression mode : LossyStream size : 518 KiB (2%)Default : YesAlternate group : 1

I downloaded several TikTok videos using right-click and download. Using FCP 10.5.4 on a 2017 iMac 27 running Ventura 13.3.1, they all worked fine.

If it is a bug in 10.5.4 or Catalina 10.15.7, that will never be fixed in those versions. You would have to upgrade as a first step. If you cannot upgrade software due to machine limits, you will have to transcode those before import using some 3rd-party utility.

To determine if it's a config or hardware problem on your 2012 MacBook Pro, you could try temporarily disconnecting any wireless audio or any type of external audio: speakers, headphones, Airpods, etc. 

You could also try killing the coreaudiod process, which sometimes will at least temporarily correct an audio glitch. Procedure:

Go to Applications>UtilitiesLaunch TerminalEnter the following: sudo killall coreaudiod

Relaunch FCP and examine audio playback for the TikTok videos.

You can also try resetting FCP preferences (step 11 on this page):  support.apple.com/en-us/HT203477

Y ou can try resetting NVRAM or PRAM:  support.apple.com/en-us/HT201255 

In case it is some kind of CPU or interrupt contention by auto-launched processes, you could create a new user profile, log in using that profile and try playing the video files in FCP there. If that makes a difference it could be an auto-launched app or something unique to your regular MacOS user profile.

Thanks for all that help! I think I will just wait for my hardware upgrade. Converting just audio to 48khz with video pass through is done in a second with Ffworks, so this will be my workaround in the meantime. Thanks for the other hints, could be useful on the future.

Here are some solutions you can try:

Convert audio sample rate: Use a dedicated audio conversion tool or software to convert the audio sample rate of the TikTok videos from 44kHz to 48kHz. This will match the timeline audio settings in FCPX and potentially resolve the issue. There are various audio conversion tools available online that can help you achieve this.

Use a third-party video converter: Consider using a third-party video converter that can convert the entire TikTok video, including both the audio and video components, into a format compatible with FCPX. This may help resolve any compatibility issues causing the audio problems. Look for video converters that specifically support FCPX or provide options for customizing the output settings.

Adjust FCPX project settings: Try adjusting the project settings in FCPX to match the sample rate of the TikTok videos. In FCPX, go to the "Project Properties" or "Audio/Video Settings" and ensure that the project's audio sample rate is set to 44kHz to match the audio sample rate of the TikTok videos. This alignment may help resolve the crackling and volume issues.

Transcode the videos: If the above solutions don't work, consider transcoding the TikTok videos using FCPX's built-in transcoding feature. In the event of compatibility issues, transcoding the videos within FCPX can help ensure that they are properly optimized for editing and eliminate any audio problems caused by incompatible formats.