[Larry the Loafer]

As VLC has been mentioned, if this is on a laptop or a PC (and assuming you're running Windows) the default refresh rate is almost always 60Hz on monitors/screens, for boring technical reasons only sad people like me understand.

You may not be able to change this on a laptop but you should be able to on a desktop, and even failing that you should be able to be forced through the monitor/TV settings to a 50Hz refresh rate.

This might be the lightbulb moment - I'm not sure whether to laugh or cry.

I loaded some test files onto a USB stick and plugged it straight into a JVC Smart TV using its built-in media player, hoping it would play at 50hz rather than 60hz (I'm going to assume the Xbox defaults to 60hz because games consoles like to be as smooth as possible) and the results were interesting. The every-half-second judder is gone. However, there is some judder I've noticed during end credits that seem to be a lot more random, almost as if the TV's processor is struggling to keep up. Annoyingly, I can't seem to find any way to display what refresh rate the TV is using, unlike my main TV, though that won't play the files anyway because it's annoyingly picky about file types.

I'll keep doing some tests, but if this is down to the displays I'm using rather than the video file itself, I might be able to breathe a sigh of relief.

UPDATE: I used the same clip from the Stanley Baxter show and re-encoded it to a constant (and probably overkill) 6000kbps and compared it to the version I was having issues with, which was encoded at RF20 (around 1500-2000kbps) and the former seemed to lack any sort of judder whatsoever. Whatever the issue might me, I think I might be safe to rule out any deinterlacing issues with Handbrake. Thank you for the lightbulb moment, Neil!

[James2001]

It would be good to see the end of interlacing really, it's often a nightmare to work with in this modern digital world. UHD is entirely progressive, but it's likely to be a long time until that becomes standard (and there's always going to be the decades of legacy interlaced content to deal with even then). My current camcorder is 1080p50 and it's a hell of a lot easier to work with when editing than my old 1080i50 and 576i50 ones were.

[Larry the Loafer]

It would be good to see the end of interlacing really, it's often a nightmare to work with in this modern digital world. UHD is entirely progressive, but it's likely to be a long time until that becomes standard (and there's always going to be the decades of legacy interlaced content to deal with even then). My current camcorder is 1080p50 and it's a hell of a lot easier to work with when editing than my old 1080i50 and 576i50 ones were.

As we've mentioned in other threads, moving over to progressive video is one thing, but bringing all the old interlaced stuff with us is something only some of us seem to care about, sadly.

UPDATE: For anyone still playing along at home, it seems to be a mix of compression artefacts and refresh rate. I upped the quality in Handbrake from RF20 to RF18 and it seems to have completely eradicated the judder on that spinning Nationwide clip. It's nearly doubled the file size though, so I'll see if I can play around with the settings some more and find a balance. But, overall, I think the mystery is finally solved. Thank you again for your insight, Neil. I would've never considered refresh rate if it wasn't for you!