The core technology and development of H.264

H.264 / AVC is the latest standard jointly introduced by the advantages of the two major organizations H.263 + and Mpeg4. The most valuable part is undoubtedly the higher data compression ratio. Under the same image quality conditions, the data compression ratio of H.264 can be 2 times higher than H.263 and 1.5 times higher than MPEG-4.

The evolution of digital video codec technology

International standards are usually formulated by the International Organization for Standardization ISO based on the technical recommendations of the International Telecommunication Union ITU. The digital video codec standard has also undergone many changes. The H264 standard has brought moving image compression technology to a higher stage. Providing high-quality image transmission at a lower bandwidth is the highlight of H.264 application. The popularization and application of H.264 has higher requirements on video terminals, gatekeepers, gateways, MCUs and other systems, and will effectively promote the continuous improvement of video conference soft equipment in all aspects.

H.264's core competitiveness

The most valuable part of H.264 is undoubtedly the higher data compression ratio. The basic principle of compression technology is to filter the non-essential information in the video file, so that the data can be transmitted faster on the network. Under the same image quality conditions, the data compression ratio of H.264 can be 2-3 times higher than that of MPEG-2 currently used in DVD systems and 1.5-2 times higher than that of MPEG-4. Because of this, H.264 compressed video data requires less bandwidth and is more economical during network transmission.

When MPEG-4 needs 6Mbps transmission rate matching, H.264 only needs 3Mbps-4Mbps transmission rate. We use transportation to make a more vivid analogy: the same is to transport a large box with a truck. If MPEG-4 can reduce the weight of the box by half, then H.264 can reduce the weight of the box to 1/4. With the same truck weight, H.264 has doubled the truck's cargo capacity compared to MPEG-2.

The price of H.264's superior performance is a significant increase in computational complexity, such as layered design, multi-frame participation, multi-mode motion estimation, and improved intra-frame prediction. These all significantly improve the prediction accuracy, thereby obtaining more Standard compression performance is much better.

Continuously improving hardware processing capabilities and constantly optimizing software algorithms are the basis for the survival of H.264. As early as ten years ago, the CPU with a frequency of tens of megabytes reached the top level, and nowadays ordinary desktop computers have a CPU frequency of up to several gigabits. According to Moore's Law, the capacity per unit area of ​​a chip doubles every 18 months, so the computational complexity added by H.264 is insignificant relative to the performance improvement effect. Not to mention the emergence of new computing methods, which also relatively alleviates H.264's hungry demand for processing speed.

Comparison of H.264 and MPEG-4

In the case of a very low bit rate (32-128Kbps), H.264 has a performance multiplication effect compared to MPEG-4, namely: H.26L media stream with the same bit rate and MPEG-4 media stream, H.264 The 26L has a gain of about 3 decibels (the image quality level is doubled). The 32Kbps H.26L media stream has a signal-to-noise ratio similar to that of 128K MPEG-4 media stream. That is, under the same picture quality, the bit rate of H.264 is only a quarter of MPEG-4.