What is bit rate and frame rate?
What is a video file, what is a frame, aspect ratio, and finally what is the bit rate?
What is a video file?
Video, like cinema itself, is a rapid alternation of images. How fast is it? For a human, there should be 24 images per second. In this case, images that change quickly become moving. This is what cinema and now video are based on. Also, each image has several properties. Which? These are the width and the height. For video, these quantities are measured in points. So many points in width and so many points in height.
What does the video consist of?
If we zoom in on any frame in our video, then we can see the individual squares that make up our image. Each of these squares received the name – “Pixel”, which comes from the English – “Element of images”, that is, an element of the image.
Pixels on the screen
So when we look at the properties of the file or the properties of the project, we see the video formats in which it is indicated how much is the height of the box and how much is its width.
video aspect ratio
In the image, we see that the width of the frame is 1920 pixels and its height is 1080. It is clear that the more pixels there are in our frames, the more details can be accommodated. And consequently, the better the image will be. And don’t forget that the frame rate must be at least 24 frames per second.
Older video formats, such as the PAL standard, consisted of 720×576 pixels. Modern HD or Full HD, already 1920 x 1080. The 4K format already has 4096×2304 pixels, and the most recent 8K format is 7680×4,320. That is, the further, the better quality is achieved.
Video aspect ratio.
This is also the parameter that for many is almost a thing of the past. The fact is that before there was a television format that had a 4/3 aspect ratio, and a wide-screen format, mainly for watching movies, that had a 16/9 ratio.
Monitor with 4×3 aspect ratio
Now the television format is a thing of the past (almost) and only the wide format remains
Monitor with a 16 x 9 aspect ratio
What is the video bit rate?
Like I said, each frame is made up of a large number of pixels. If we try to put this amount on our hard drive, it will take up too much space. In fact, the arithmetic here is simple. Let’s count.
One frame – 1920×1080 = 2,073,600, that is, two megabytes (actually, this is not entirely true, but I’ll simplify it a bit)
That is, we now know that a painting we have weighs 2 mb. It seems a bit, but let’s keep counting.
One second. There must be at least 24 frames in one second. What do we get? 24×2 = 48 mb.
One minute. 48×60 = 2880 mb. I mean, think about it. In one minute, almost 3 gig! Well, how long will an hour take then?
One hour 2880×60 = 172800 mb. In other words, a one-hour movie will occupy 172 gigabytes of memory.
Well, since such a thing will not work, smart people decided: it is necessary to squeeze. We need to compress the video to fit everything on a computer, on a phone. What can be seen on the Internet, etc. And that is why there are various video formats. Since each format has its own rules for compressing video.
But here we come to the concept of bitrate.
Bitrate: read / write speed. You are recording a video. The video camera matrix takes measurements of light, that is, it measures pixels. Transfer them even further, to a USB flash drive or SSD. The speed of this transmission is the bit rate.
Next, we watch the video. At this time, the data is read from memory and transferred to the monitor / screen. Once again, we are faced with a certain data rate.
But in the video, the function of the bitrate value is somewhat different. Video Bit Rate: The compression rate of the video. When video is recorded from the matrix, the signal is immediately encoded and compressed. The more the signal is compressed, the less space it takes up, but at the same time, the lower the quality.
