VBR and CBR Differences _h.264

The difference between CBR encoding and VBR encoding in video coding VBR is a variable bit rate, which differs from constant bit rate cbr in that the difference between CBR or VBR encoding is as follows:

By using the Windows Media Encoder, audio and video content can be encoded using constant bit rate (CBR) or variable bit rate (VBR).

CBR coding
It is most effective to use CBR coding in streaming playback scenarios. When using CBR coding, the bit rate is basically constant in the process of flow and close to the target bit rate, always in the time window determined by the buffer size. The disadvantage of CBR coding is that the quality of encoded content is not stable. Because some fragments of content are more difficult to compress than other fragments, some parts of the CBR stream are inferior in quality to others. In addition, CBR coding causes the quality of adjacent streams to be different. Usually at lower bit rate, the change of mass is more obvious.

VBR encoding
Use VBR encoding when you plan to provide content for users to download, play locally, or play on a device that has a limited read speed, such as a CD or DVD player. (You can also use peak VBR encoding when scheduling streaming content) when the encoded content is mixed with simple data and complex data (for example, video switching between fast and slow actions), VBR encoding is advantageous. When you use VBR encoding, the system automatically assigns fewer bits to the simple part of the content, leaving a sufficient amount of bits to generate a high quality complex portion. This means that content that is constant in complexity, such as news broadcasts, does not benefit from VBR encoding. When using VBR encoding for mixed content, the output of VBR encoding is much better than that of CBR-encoded output in the same file size. In some cases, a VBR encoded file with the same quality as the CBR encoding file may have only half the size of the former.

Under normal circumstances, the synthesis of the same quality of the program, the use of CBR coding when the program synthesis time will be shorter, but the length of the file will be larger (that is, the same length of the program will occupy more space or the same space can only accommodate a shorter program).

1, VBR suitable for the application of the scene is media storage, rather than network transmission, so do not let the martial arts champion to become a civilian;

2, in fact, the actual network transmission in the so-called CBR is generally ABR (average bit rate), that is, as long as the unit time in the rate control at the rated rate on the code, because the output of the code will have a buffer can play the role of smooth fluctuations;
3, what you call a strict CBR Each frame is assigned the same code word, imagine, if a frame of the required code is very small, and you must give it a lot of code words, it is not a waste. On the other hand, if a frame requires a lot of code, and you give very little, the effect of this frame will be very poor. In this way, the overall quality of the sequence will be suddenly and well, and constantly jump, but the visual impact is very large; therefore, ABR is the most suitable scheme for network transmission.
4, whether CBR, ABR or VBR are part of the code rate control, and the rate control is the open part of video coding, It does not change the legitimacy of the code flow structure, so no matter in MPEG2, MPEG4 or H.263, H.264 do not make provisions;
5, because the current video coding standards are based on block-coded hybrid coding framework, So a bit rate control algorithm can be used on any protocol (of course, sometimes need to do a little change), but the control effect is not good problem, no RC is exclusive which protocol.