H. MPEG-4, also part tenth, is a joint video group composed of the ITU-T video Coding Expert Group (VCEG) and ISO/IEC dynamic Imaging Expert Group (MPEG) (jvt,joint Team) proposed standard for highly compressed digital video codecs. This standard is often referred to as H.264/AVC (or avc/h.264 or h.264/mpeg-4 AVC or mpeg-4/h.264 AVC) and clearly describes its two developers. The main parts of the H264 standard are Access unit delimiter (Access unit separator), SEI (additional enhancement information), primary coded picture (basic image encoding), redundant coded Picture (redundant image encoding). There are also instantaneous decoding refresh (IDR, instant decode refresh), hypothetical Reference Decoder (HRD, hypothetical reference decoding), hypothetical Stream Scheduler (HSS, Imaginary bitstream Scheduler). The advantages of H:1. Low bit rate: compared with MPEG2 and MPEG4 ASP compression technology, in the same image quality, the amount of data compressed with H. 1/3 is only MPEG2 of 1/8,MPEG4. 2. High-quality Images: H + + provides continuous, smooth, high-quality images (DVD quality). 3. Strong fault tolerance: the necessary tools for solving errors such as packet loss that can occur in an unstable network environment are provided. 4. Network adaptability: H. Abstraction provides a network abstraction layer, so that the files of H. E can be easily transmitted across different networks (e.g., Internet, cdma,gprs,wcdma,cdma2000, etc.). The biggest advantage is the high data compression ratio, in the same image quality conditions, the compression ratio of H. MPEG-2 is more than twice times, is the MPEG-4 1.5~2 times. For example, if the original file size of 88GB, using MPEG-2 compression standard compression into 3.5GB, compression ratio of 25:1, and the compression standard of H. 102:1 to 879MB, from 88GB to 879mb,h.264 compression ratio to achieve a staggering. The low bit rate, which plays an important role in the high compression ratio of H. MPEG-2 and MPEG-4 ASP compression technology, will greatly save users ' download time and data traffic charges. In particular, it is worth mentioning that the high compression ratio at the same time, but also has a high quality smooth image, because of this, after the compression of the video data, in the network transmission process requires less bandwidth and more economical. The main features of the H264 standard are as follows:1. Higher coding efficiency: it is possible to save an average of more than 50% of the code rate compared to the standard rate efficiency of h.263. 2. High-quality video: The high-quality video image can be provided at low bit rate, and high-quality image transmission on the lower bandwidth is the highlight of the application of H. 3. Improve network adaptability: H. E can work in real-time communication applications (such as video conferencing) in low-latency mode, or in video storage or video streaming servers without latency. 4. Using a hybrid coding structure: Same as H.263, H. B also uses a hybrid coding structure using DCT encoding plus DPCM, and also adds new coding methods such as multi-mode motion estimation, intra-frame prediction, multi-frame prediction, Content-based variable-length coding and 4x4 Two-dimensional integer transformation, which improves coding efficiency. 5. There are fewer coding options: in H.263 encoding, it is often necessary to set a considerable number of options, increasing the difficulty of coding, and H. A "Return to basics", reducing the complexity of coding. 6. It can be used in different situations: H. I can use different transmission and playback rates depending on the environment, and provides a wealth of error handling tools to control or eliminate packet loss and error. 7. Error recovery feature: H. e provides a tool to solve the problem of network transmission packet loss, and is suitable for transmitting video data in wireless networks with high BER transmission. 8. High complexity: 264 performance improvements are achieved at the expense of increased complexity. It is estimated that the computational complexity of the coding is approximately 3 times times that of H.263, and the decoding complexity is approximately twice times that of H.263.
The advantages and main features of H.
