Video Basics and Compression Part 2
The amount of data is huge because video is made up of a series of “still images.”
Therefore, as it is, the amount of data is large and unwieldy (cannot be handled), so “compression” is required.
Compressing video is called “encoding.”
Encoding is “scrambling the data”, which refers to the conversion (compression in this case) of the data according to certain rules (compression algorithms).
Restoring the converted data to its original state is called “decoding.”
Please note that it does not necessarily include audio
It’s easy to think of video as “audio is a set”, but that’s not the case.
Certainly it generally comes with audio that is in sync with the video, but since “video” is just a “continuous still image” it can be called “video” even if it does not come with audio data.
Machine Vision Page
Video Data Terms
From here, I will explain the terms related to “compression” of video data.
frames per second
Bit rate
Compression rate
Drawing method (progressive, interlaced)
These words are “video specifications” and are closely related to compression.
frames per second
The frame rate represents the number of still images per unit of time.
In the case of video, it generally refers to “how many still images are composed per second”. The unit is fps (frames per second).
Explanatory frame rate drawing
For example, in the case of “5 still images per second”, 5 fps.
In the case of “10 still images per second”, it is 10 fps.
The frame rate represents the “smoothness of movement”.
For example, if the frame rate is small, it will be a “messy video”. On the other hand, the higher the frame rate, the smoother the motion of the video, but the greater the amount of data.
Bit rate
Bit rate is the amount of data per unit of time.
The frame rate was “the number of still images per second”, but in the case of bit rate, it means “the amount of data per second”.
If the frame rate is high, the amount of data will be large, so the bit rate will also be high.
Also, if the resolution of the “still image” is high, the amount of data will be large. (Comparing HD and Full HD, Full HD has a higher amount of data.)
Compression rate
It is a percentage that shows how much the amount of information in the compressed data has decreased compared to the original data.
