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Optimal codec standard: H.265 or H.264?

Issuing time:2019-11-17 20:34Author:zonda.cam@gmail.com

Optimal codec standard: H.265 or H.264?


When it comes to improving the video streaming quality of video surveillance, it is impossible to mention H.265, the most efficient video encoding and decoding technology standard. H.265, also known as HEVC (High Efficiency Video Coding), is a video coding technology designed to significantly reduce the video stream rate while maintaining the highest available image quality. Compared to its predecessor technology (H.264), H.265 can provide approximately twice the compression ratio while ensuring the same video quality; or it can greatly improve image quality with the same code stream. Its theoretical maximum resolution reached 8192*4320, including the 8K UHD format.


With the rapid development and large-scale deployment of IPC, the HD video processing of security video surveillance is constantly deepening. The lens specifications of the front-end equipment and the display resolution of the back-end are simultaneously improved, and the video codec standard needs to be changed accordingly.


H.265 advantage


As the H.265 format enters the market, it is gradually being deployed in HD IP cameras and NVR products. H.265 can reduce storage capacity by approximately 50% due to the improved efficiency of its algorithm. The two video encoding and decoding technologies of H.265 and H.264 work by comparing video single frames to find duplicate frames. These redundant parts are replaced with a small amount of alternative data information that can represent the original content. The difference between the two is the ability of the H.265 technology to amplify/reduce the CTU (coding tree unit) block. The CTU size of H.265 is between 4*4 and 64*64, while the H.264 technology only allows CTU blocks of size 16*16. For the enhancement of CTU segmentation, as well as better motion compensation and spatial prediction, a large amount of signal processing capability is required.


In addition to using CTU to achieve reduced code streams, H.265 also relies on parallel computing to make its own encoding process faster. It supports AVX/AVX2, FMA3/FMA4 and other extensions, and the single rectangular area of the image during operation is independent of each other, thus supporting parallel processing. H.265 also has a capability that H.264 does not have, namely WPP (Wavefront Parallel Processing) technology, a decision tree technology that makes the compression process more efficient.


In summary, H.265 compression technology is an efficient video coding technology, which has greatly improved in three aspects compared to its predecessor technology. H.265 technology means smoother video playback, lower latency, and smaller storage. For the advanced HD video surveillance field, the better image quality means more advanced intelligent processing and analysis operation space; lower code stream and storage space means lower total ownership. Cost, technical point of view, the advantages outweigh the disadvantages.


However, H.265 is still far from large-scale deployment. In the long run, there should be a long period of time when both H.264 and H.265 coexist.


H.265 development obstacles


At present, the development of H.265 technology is largely hindered by the optimized H.264 technology (currently H.264 is the technical standard available in most scenarios in the industry) and the high upgrade cost. In addition, the reasons for the development of H.265 may also be due to the industrial chain factors - improved production equipment and processes to produce equipment compatible with H.265 standards, and patent licensing fees.


Limitations of laboratory testing


According to the test of ICT-VC (Joint Collaborative Team on Video Coding), the compression ratio of H.265 is doubled compared with H.264, but this is only the test data of the laboratory, not the test of the actual environment. Data, so it is completely impossible to reflect the complexity of the real environment. Therefore, the current H.265 claims to double the H.264 compression performance still stays at the theoretical value.


In contrast, H.264 has been adopted in the industry for more than 10 years, and its performance has been well known by users. At the same time, it has the most abundant selection of encoders and decoders. The industry chain has support from chip and board manufacturers. All aspects tend to be stable.


High patent fees


Another issue that hinders the widespread deployment of H.265 is patent licensing. H.264 benefits many companies in the industry, and H.265 is not a free new tool. H.265 is not popular at this stage, and its patent ownership problem has not been unified, resulting in high patent costs. For security companies, this is a problem that has to be faced, and it needs to be taken seriously, because it is related to manufacturing and the cost increase for customers: in order to be compatible with the new standard, the front and rear devices need to be updated and upgraded, how can we make Customers are convinced that all the extra expenses are worth it?


Video codec standard development follow-up


The development of video codec can be summarized in a 10-year phase: In 1994, the MPEG2 specification appeared. In 2003, the H.264 standard appeared. In 2013, H.265 appeared.


When MPEG2 appeared, the focus of the industry was mainly on DVD players and standard definition televisions. MPEG2 can be used very well for these devices. Subsequently, the emergence of H.264 matched the needs of IT, mobile Internet, HD resolution, etc., and promoted the development of HD digital TV, Internet video, mobile video, video surveillance, Blu-ray video and other applications. H.265 also has its own use, and will be used in advanced applications such as Ultra-HD Ultra HD scenes and cloud computing.


With the development and application of H.265, its founding agency ICT-VC has established a new team (IVET), focusing on stronger compression technology. At the same time, another organization, AOM (Alliance for Open Media), was established to establish an Internet video standard. Its members include a number of Internet and technology-related companies such as Microsoft, Google, Intel, and Amazon.


For security, the H.265 standard has its technological leadership, but H.264 is more usable and economical at this stage, so there is no global optimal codec standard, and only the most appropriate standard for the scenario needs. However, it is foreseeable that the evolution of video codec standards will be accelerated by the investment and competition between different organizations. Perhaps the future development of video codec will no longer follow the 10-year development law and faster pace of development.


keywords: optimal codec standard, H.264, H.265


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