Recently I had a very weird behaviours on some videos imported on my MacBook Pro 2018 with Touch Bar and since I have a very high specs Mac I was surprised to discover that it was the MacBook the real cause.

Let’s start from the beginning.

I created some videos on my iPhone, and later also on my iPad, using different mobile apps. After that I imported those videos on my MacBook using AirDrop first, then emails and iCloud Drive. I tried the latters just to make sure the problem wasn’t in the way I was importing the files.

I played back the videos on my Mac and they were laggy. I imported different versions of the same videos, in 4K and also 1080p at 30fps and 60fps. The issue was visible only on my MacBook and online if the videos were uploaded from my MacBook.

In my mobile devices everything did run smoothly whilst on my mac it was like a frame or two was missing here and there, every x amount of seconds.

After few tests I got in touch with support for each of these apps. They helped me to track down the issue but nothing seemed to work. Obviously they suggested it could be an issue with my MacBook but I did not want to believe that.

I didn’t believe it until they asked me to check if I had the same issue with apps like iMovie. To be honest I didn’t think about that, I didn’t even try to play a movie as I was quite sure my MacBook was fine. So I created a video on iMovie, I exported on my Mac and I saw with surprise that the video was laggy. At that point I realised that my MacBook could be the issue.

I did some research online until I read one line on a forum that suggested to reset the PRAM. After the reset, everything runs without any problem but unfortunatelly just for few hours.

How to reset the PRAM

In general, resetting the PRAM (or NVRAM) does not result in data loss or problems. It’s one of the first interventions of the Genius at the Apple Store, so if your Mac has some weird behaviours then don’t be afraid to use it.

The following procedure works on all models, including those with the T2 security chip.

So let’s start by shutting down the machine and then just hold down the keys at the same time:

1. Hold Command⌘ + Option + P + R at startup
2. Wait two or three initial booting sounds (in the case of newer Macs, wait for the apple to appear for the second time)
3. Let the machine restart normally

Warning: If there is a firmware password set on the Mac then this keys combination has no effect or causes the Mac to boot from macOS Recovery. In this case to reset the PRAM first you need to disable the firmware password and then start the procedure at point 1.

I am still investigating the root cause of this issue because it could also be battery related.