But not every moment of video changes all that much from frame to frame. Most data in video represents information changing because the picture constantly changes. The purpose of variable bit rates is to split the difference between file size and quality. Like the terms imply, a bit rate can vary within a file, where some data is processed faster than other data, or it can remain constant, with the same amount of data processed per second, every second. This can matter when recording video and you only have so much recording media space, or if you want upload video to the Internet very quickly. But if the quality doesn’t matter as much the length, then lower bit rates are better. If you need the very highest quality regardless of file size, then higher bit rates are better. Which is better? It depends on your needs. The upshot is that you can have the same video in a smaller file size, but the quality won’t be as high. Lower bit rates can mean lower quality, but smaller file sizes per second of video. So, higher bit rate equals higher possible quality, but also higher file sizes. It also means it’s more taxing on a computer or player to process more data, and the file size required for the length of the video is higher.
The higher the bit rate, the more data gets pushed through per second, meaning the amount of information is higher, supporting higher resolutions, higher frame rates, and overall higher quality. The number of bits – each zero or one – processed per second is the bit rate. When digital video plays, instead of physical frames running through a projector, a video player processes massive amounts of data in the form of ones and zeros.