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
Video (and audio!) is compressed in a way that causes quality loss. The objective is that the loss is minor and your eye/ear shouldn’t notice it, but it’s there.
How much loss happens, and how effective the compression is, are settings for when you encode and save the video. Discarding more image quality will make the file size shrink dramatically, but also cause the image to look more and more distorted when you play it. In the most extreme it can look like everything is blurry and out of focus, but the file size is tiny compared to what you’ve been looking at.
Sometimes you can tell the software to spend more effort on compression, and save a few megabytes on a long video. The downside is saving takes longer. Having a 30 minute video take anywhere from 5 to 60 minutes to encode (compress) is completely normal depending on if you have the quality turned way up or way down. Graphics cards can assist, but they don’t offer as much quality flexibility.
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