Video bit rate
Today, we are going to popularize the concept of bitrate in video playback.
Data rate refers to the data flow used by a video file in a unit of time, also called bit rate, sampling rate, and bit stream rate. A popular understanding is that it is the most important part of image quality control in video encoding. Generally, the unit we use is kb/s or Mb/s. Generally speaking, at the same resolution, the higher the code stream of the video file, the lower the compression ratio and the higher the image quality. The higher the bit stream, the higher the sampling rate per unit time, the higher the data stream, the higher the accuracy, the closer the processed file is to the original file, the better the image quality, the clearer the image quality and the higher the decoding capability of the playback device is required.
Of course, the larger the code stream, the larger the file size. The calculation formula is file size = time X code rate/8. For example, a 720P RMVB file with a 1 Mbps stream of 90 minutes is common on the Internet and its volume is = 5400 seconds × 1 Mb/8 = 675 MB.
Generally speaking, a video file includes both image and sound, such as an RMVB video file, which contains both video information and audio information. Audio and video have their own sampling methods and different bit rates, that is, the same video Audio and video file bit rate is not the same. And what we’re talking about is the bitrate of a video file, which generally refers to the sum of the bitrate of the audio and video information in the video file.
Taking the most popular and familiar RMVB video file in China as an example, VB in RMVB refers to VBR, which is short for Variable Bit Rate. The Chinese meaning is variable bit rate, which means that RMVB adopts the dynamic encoding method. , use a higher sampling rate for complex dynamic images (singing and dancing, flying cars, wars, actions, etc.), and use a lower sampling rate for static images, make rational use of resources and achieve the image quality and volume effect
The most fundamental difference between code rate and sample rate is that the code rate is for the source file.
There are many types of encoding formats. With the continuous advancement of technology, various encoding formats have been produced for different purposes. The compression rates of different encoding formats are different and have their own characteristics. Some of them can maintain high image quality in the case of low bitrate, but in the case of high bitrate, the image quality indication is not great and some are suitable for high bit rates. High definition image is maintained, but may not work well at low bit rates. Present some common ones.
