GH4 video judder/strobing - a solution

Started Nov 15, 2014 | Discussions thread
left eye
OP left eye Senior Member • Posts: 2,297
Re: 60hz monitors are capable of smooth 24p playback

fotochop wrote:

I have ripped and watched a ton of 24p video over the years on my 60hz monitor with no motion issues or judder apart from when the camera pans too fast - which will cause judder anywhere, even on cinema screens.

The majority of inbuilt laptop screens are fixed at 60Hz, the processor driving them has to resort to 3:2 pulldown to make the maths work, 24 into 60 doesn't go. The result will be judder.

External monitors that have a maximum refresh rate of 60Hz, are usually flexible, and can run at lower refresh rates - controlled by the computer's graphic processor.  I suspect your 60Hz monitor is running at 48Hz when being fed a 24fps signal.

The point is not all 60Hz monitors (or greater rates) are flexible enough to run at all lower rates, usually they can handle 50Hz to display the European standard of 25fps broadcast - used for many many decades.  24fps although having been widely used in the film industry wasn't a 'household' standard until relatively recently - in the past few years many more monitors are able to reduce their refresh down to 48Hz - but not all, especially in the 4k realm.

Out of interest, what is the make/model of your monitor?

Take the Planet Earth blu-ray for example. I own that and ripped it to 24p. Plays silky smooth on my computer, even when the camera glides over mountains, there's no judder. My own 24p video camera footage is also smooth and judder free - except when I pan too fast.

The answer is software. You don't need a new monitor with 48hz refresh rate, you just need a software player and codecs capable of handling 24p. There is likely some clever interpolation happening to achieve these results, but with today's software players taking advantage of graphics hardware acceleration, the task is effortless for your computer.

I use PotPlayer on my Windows PC, and it is hands down the best video player. VLC was good for many years, but when I moved to PotPlayer it was a step up. If you're on Mac, there are no doubt software video players that can play 24p without judder, although I wouldn't know for sure since I don't own a Mac.

Just thought I'd add this, because your suggestion of plugging in an external display with 48hz refresh capability is an extreme length to go to for smooth playback. Just get a decent software video player.

BTW, there's lots of 24p videos on youtube that users have uploaded, including GH4 24p video. Youtube supports 24p, just right click and choose stats to confirm it's 24p, then you can at least see whether your browser can handle 24p video. Some can't. 24p video in my Firefox browser is not pretty, lots of judder. The same video file when played in PotPlayer is smooth.

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