[General Topics] Hendrix7:
TLDR: You don't need to pay for camera apps to "increase the bitrate". Just pick a higher resolution and the bitrate boost comes with it, and more benefits!

When the Galaxy Note 3 was released in 2013 with its 4K video recording capability, I lost count of how often I heard people commenting "B… b… but I don't have a 4K screen!!! So why in the world would I need this?!", and variations thereof.

So you thought the conventional wisdom that "anything above 1080p makes no difference on a 1080p screen"? You thought "I don't need to record in 4K because I don't have a 4K screen!"?

Well, I am here to tell you a secret: 2160p video looks crisper and sharper on a 1080p screen than 1080p video can ever hope to appear. In fact, 2160p video even looks visibly better than 1080p video on the screen of a little 1366×768 netbook.

While edges look rather dull on 1080p video, they look crystal clear on 2160p watched on a 1080p monitor!

Why is that? Well, two reasons. Chroma subsampling and bit rate.

Bit rate​

First, 2160p videos have a higher bitrate. Smartphone camera software typically uses around 18 Mbit/s for 1080p and 48 Mbit/s for 2160p, though it may vary depending on vendor.

This means the 2160p video has more information density and less information discarded by compression. These blocky compression artifacts become far less visible:

View attachment 6076782

(source: JPEG Compression Artifacts § Session 06 - CSS and Images; file)

Tom Scott explaining video compression:

(URL if embedding does not work: Why Snow and Confetti Ruin YouTube Video Quality)

Chrominance subsampling​

Second, did you know that your 1080p "Full HD" video only has 540p of colour information?

That's right. "Full HD" has 1080p of luminance (brightness) information, but only 540p of colour. That is the reason the edge of items in 1080p videos appears to look not so sharp.

Why is this done? Because luminance is far more important than color to our brain, and our eyes have more brightness-sensing rods than colour-sensing cones, so having "4:2:0" chroma subsampling, meaning 1 colour pixel for 4 luminance pixels, is an opportunity to save lots of disk space.

Remember, video compression is about discarding information where your brain notices it the least.

Let Captain Disillusion explain the rest:

(CD / Color - in case embedding does not work.)

Also:

(Why Does 4K Look Better on 1080p Monitors - YouTube)

4K is future-proof. 1080p? Not so much.​

YouTube has removed the "HD" label from its 720p option in 2020, which is a sign that 1080p is now on the low end of what is considered "HD".

2160p 4K is more "future-proof" because it can be enjoyed on any 4K screen you might own in the future, so "I don't have a 4K screen" is the worst argument in existence not to record in 4K. Some video players such as mpv and celluloid and VLC have a zooming feature, so 4K video also allows for more zooming. 4K video can also be more cropped in video editing while retaining a good quality. 8K (4320p) even more so.

The only reasons to record at a lower resolution are to get a higher framerate for action scenes, and to save space when recording less important events where a high resolution is not necessary, and when you are low on free space or battery charge and want to extend the remaining recording time.

But for important events, don't hesitate to crank the resolution up to the max. Your future self will thank you.

[I hereby release this text under the Creative Commons 4.0 ShareAlike license.]