From MPEG to H.264: evolution history of video compression standards

In the history of video monitoring, there have been multiple video compression standards. 1. The standards defined by the ITU for low-Bit Rate video calls, including H.261/2/3 and ISO for consumer applications, the MPEG standard is defined for motion image compression, including mpeg1/2/4. The cooperation between ITU and ISO defines H. 264 codec technology, some standards still exist. Figure 1 briefly describes the development history of the video codec standard.

Mpeg1 and MPEG2 are many standards used in the early days and have basically exited the stage. At present, M-JPEG, MPEG4 and H.264 are mainly used. We compare these standards through the following points. Because the mpeg1 and MPEG2 standards have faded out, we will not perform much analysis here.

· Implementation cost: includingAlgorithmThe complexity and resource occupation of implementation, the difficulty and cost of technical acquisition, and the cost ultimately reflected in the product;

· Encoding performance: it is mainly reflected in the bitstream size obtained after compression under the same primary and objective visual quality, which is critical for network transmission and storage;

· Network support: the quality of network support depends mainly on the fault tolerance capability of network packet loss and errors and the adaptive capability of support networks;

· Application support scope: due to the ever-changing application requirements in the video monitoring field, the support capability of a platform for different needs is also very important;

· Future potential: from a development perspective, the potential of a standard is reflected in the wide range accepted by the industry in the future, and the smoothness of transformation in related applications, and the degree of support for interconnection.

M-JPEG may be the lowest possible cost of implementation. In fact, there are a lot of video front-end acquisition chips have integrated M-JPEG, can directly output the M-JPEG code stream, which is why M-JPEG in many low-end products are still the main reason for the application. At the same time, the frame encoding of M-JPEG is independent of each other, which is conducive to video editing and other applications, and is less affected by packet loss in network applications, however, because it is much larger than other standard code streams, it seriously affects its ability to provide high-quality network videos. In the other three aspects, M-JPEG and MPEG4, H.264 compared with a significant disadvantage. As video surveillance market requirements for video compression increase and MPEG4, H.264 implementation costs continue to decline, the market share of M-JPEG may continue to decline in the future.

The implementation cost of MPEG4 has been greatly reduced over the past few years with the maturity of the solution, and the choice of the solution is also expanded accordingly, from DSP to ASIC. However, there is still a big gap in encoding performance compared with H.264. MPEG4's support for the network environment is not enough in terms of preparation and timing. The advent of the network era in the video monitoring field has led to more and more considerations for network support, the coding efficiency of MPEG4 restricts its support for a broad application environment to a certain extent. In the final analysis, MPEG4 decided its fate as a transitional standard from the very beginning. The reason why the Standards Committee re-enacted the H.264 standard in a short time is to replace it.

H. 264 standards should be the highest among all standards in terms of implementation costs, which is also related to the latest time it was developed, of course, its computing complexity is indeed much higher than other standards. However, as H.264 is more and more widely used in the video surveillance field, it can be seen that the ready-to-use cost is also declining. From the aspect of coding performance, H.264 is far better than MPEG4, saving an average of 264 of the transmission code streams, which can greatly improve the efficiency of storage devices and network utilization. The superior coding performance determines H.264's ability to support a wider and changing application environment, including the ability to adapt to the network environment. From the perspective of network support, whether wired or wireless, the network application is H. one of the important directions for the 264 system timing, its code stream syntax definition and different encoding options are advantageous to H. 264. From the global video application market, H. 264 has become a mainstream standard in fields such as television and 3G, and has rapidly grown into one of the mainstream standards in the video surveillance field. The trend of replacing mepg4 is clearly visible. With the construction of large-scale video surveillance networks and the enhancement of interconnection requirements, H.264 will surely become the mainstream video standards that must be supported globally.

Table 1 provides a relatively intuitive comparison result by scoring each video standard item by item (scoring is based on a 5-Score System, with 0 being the worst, and 5 being the highest ).