Why do same videos of the same resolutions have different sizes?

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I noticed that a certain video had several ‘versions’ and all of them were the same 1080p resolution, but they all differed in sizes. Some versions differed by a few MB, but it could range from around 300 MB to more than 1.5 GB! All of them have the same length and resolution and are exactly the same video. Also, a 720p version of that video was twice the size of some of the 1080p versions despite it being the same video.

I noticed something similar in some other videos as well. They all have the same length and resolution, and are even the same video, but their sizes differ by several times. Why is that the case?

In: Technology

6 Answers

Anonymous 0 Comments

u/DeHackEd is correct here. (I’m a video editor animator for 20+ years now). There are different kinds of video compression and they’re usually variable. Most video editing software has some default rendering outputs, to create your final version; but you can usually go deeper and customize the settings, if there’s a target file size you’re shooting for. There are compression schemes for editing (smaller file sizes but minimal compression) and for delivery (a lot of compression, and compressed in a way that makes editing difficult).

I’ve done things like video banner ads for web sites that aren’t really standardized (like a small local news and events website for a small community), and they will tell you the physical size of the video (how big it appears on screen, the pixel dimensions that fit their page) and a maximum file size (how much storage it takes). I’ve done them where their specs were like “maximum 20k” for a 10 second spot, and when I compressed the edit to that point, it *really* looked like ass; where 60 or 80k file size would have looked pretty good, by 20k it was a hot mess. Same “size” and length of video.

Just like saving a JPEG from Photoshop – set it for 90% and it looks great, 60 and you may not see much difference, but 10 or 20? It’ll look like you need to clean your glasses.

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