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Audio of imported video contains cracks that the original doesn't have.

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Leon Zandman
Audio of imported video contains cracks that the original doesn't have.
on Jan 11, 2017 at 1:52:13 pm

I've recorded a live concert video using my iPhone 6S. It sounds pretty nice, even though some parts are too loud and get distorted a bit.

I've imported this video into Final Cut Pro X and noticed the audio contains cracks (crackling sounds) when played from FCP. These are also present when I export the video from FCP. These cracks aren't present when the original video file is played on my iPhone or from my Mac. It seems FCP somehow introduces the cracks. I didn't add any audio effects, so FCP should just use the original audio.

I've imported the video multiple times, trying different settings (creating optimized media / using proxy files). This all didn't make any difference. The cracks are already present in the imported video, so switching project audio settings doesn't seem to matter (i.e. the source is already contaminated).

Does anybody know what's happening here?

This is more or less a cross-post of a question I asked on the Apple Communities. I don't know if that is allowed, but I'd really like to solve this issue...
https://discussions.apple.com/message/31240318


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John Fishback
Re: Audio of imported video contains cracks that the original doesn't have.
on Jan 11, 2017 at 3:32:38 pm

You said that the original gets very loud and distorted. That same distortion will exist in FCPX, although, it may present in different ways. The crackling (it'd help if you upload an example) is distortion. Usually it's caused by audio that is too loud. Analog audio let us get away with recording very loud content without distortion. However, with digital audio, once you exceed 0, the audio will clip (distort).

How are you monitoring? Are you monitoring the original in a different way than FCPX? There are a number of amplifier stages that coupd be distorting: the power amp, a preamp, a mixer, an interface.

The first thing I'd try is to lower the level of the clip in your timeline and see what happens. You won't remove the distortion you hear in the original, but it might help with other areas of your content. The only way I've been able to reduce clipping distortion is with iZotope RX5 Advanced (other versions might do that as well).


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Leon Zandman
Re: Audio of imported video contains cracks that the original doesn't have.
on Jan 12, 2017 at 8:52:37 pm

It's not the distortion. As I said some parts of the recording are distorted due to the high audio volume during the concert. iPhone has gotten better at recording live music events (though my old Nokia Lumia excelled at that), but it still sometimes introduces distortion. This however seems to be something different. The audio graph in FCP does show reds, but even when I lower the volume the crackling can be heard. Adding compression/limiting also didn't help.

I've monitored the audio using the built-in speakers of my MacBook and some connected headphones. Both exhibit the same crackling. I've played back the video using the macOS built-in videoplayer (pressing space bar with the file selected). I've also played it using VLC Media Player and Quicktime Player. The crackling is totally absent when playing through those apps. But when I import that exact same video into FCPX, the crackling is introduced. It's maddening.

Lowering the volume on the track inside FCPX didn't help. Then the crackling just plays back at lower volume. I've uploaded a small section containing the crackling to YouTube:






I would expect an imported video with no additional effects applied to look and sound exactly the same, both video and audio, as the original.


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John Fishback
Re: Audio of imported video contains cracks that the original doesn't have.
on Jan 12, 2017 at 10:07:52 pm

I'm not sure what's going on. What's the sample rate of the original file? FCPX (and other professional NLEs) like 48K and 16 or 24 bit wav or aiff files. That might affect t he audio if different. You could try transcoding the phone video to ProRes with Compressor and see if that makes a difference. Also, it's possible some bit in FCPX has become corrupt. If you know someone with FCPX see if they'll import and play the file. If no crackling, then you should trash your prefs and even reinstall FCPX. If they hear crackling, too, then it's something in the file. You might post this question in the Audio Professionals forum. Some of those folks use FCPX.


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Leon Zandman
Re: Audio of imported video contains cracks that the original doesn't have.
on Jan 12, 2017 at 10:51:49 pm

I think I have solved it! I did a "Get Info" from the Finder on the video file. There it showed the original video file came from my Google Photos account (the "Where from" metadata pointed to a Google URL). I then remembered I had downloaded this video from my Google Photos account, because at that time the video hadn't yet been uploaded to my iCloud account, so I wasn't able to get it onto my Mac.

I used the Macos Photos app do download the original file from iCloud. This time it was a .MOV instead of the .MP4 that came from Google Photos. And this file imports without the crackling into FCPX.

So to recap: my iPhone uploaded the video file to both Google Photos and iCloud. When I download the video file from Google Photos it results in a video that has crackling sounds in FCPX. When I download the file from iCloud Photos library it imports without the crackling.

For both movies Quicktime Player lists the following info:

Format: H.264, 1920x1080, AAC, 44100 Hz, Mono. FPS: 29,98 (8,82 Mbit/s).


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John Fishback
Re: Audio of imported video contains cracks that the original doesn't have.
on Jan 13, 2017 at 1:03:19 am

Excellent. I'm glad it worked out.


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