What is 4K H.265 decoding? What's the use?

What is 4K H.265 decoding? What's the use? If you want to understand the meaning of H.265 decoding in TV, you need to know what H.265 is.


Quick description:

H.265 is a new video encoding popular in recent years. While ensuring the video quality, the video capacity is greatly reduced. Before that, it was H.264 encoding. This encoding has been accompanied by us for more than 10 years. Most of the videos you watch and download are always encoded.

For example: H.264 video clip 20G, compressed into H.265 encoding can become about 10G, so greatly save the video space, especially in the prevalence of 4K era, just a 4K movie is a few hundred G, so must There must be better code support to promote the rapid development of 4K.

H.265 decoding:

Because this is a brand new video coding technology, hardware support is required.

Depth understanding:

Before discussing the enhancements and advantages of H.265, we might as well take a look at H.264.

H.264, also known as MPEG-4 AVC (Advanced Video Codec), is a video compression standard and is also a recording, compression, and distribution format for high-precision video that is widely used. H.264 is known as a codec standard for Blu-ray discs, and all Blu-ray players must be able to decode H.264. More importantly, because Apple initially resolutely abandoned Adobe's VP6 code and chose H.264, this standard will enter hundreds of millions of iPads and iPhones and become the domain of current video coding. Absolute overlord, with over 80% share. H.264 is also widely used in network streaming media data, various high-definition television terrestrial broadcasts, and satellite television broadcasts.

H.264 has some new features compared to previous coding standards, such as motion compensation for multiple reference frames, variable block size motion compensation, intra-prediction encoding, etc. By using these new features, H.264 has more than other coding standards. High video quality and lower bit rates have also been recognized by people.

The coding architecture of H.265/HEVC is roughly similar to that of H.264/AVC and mainly includes intra prediction, inter prediction, transform, and quantization. Deblocking filter, entropy coding and other modules. However, in the HEVC coding architecture, the whole is divided into three basic units: a coding unit (CU), a prediction unit (PU), and a transform unit (TU).

Compared to H.264/AVC, H.265/HEVC provides more different tools to reduce the code rate. In terms of coding units, the size of each macroblock (MB) in H.264 is a fixed 16x16. Pixels, and H.265 encoding units can choose from the smallest 8x8 to the largest 64x64. For example, the area with a small amount of information (the color change is not obvious, such as the red part of the car body and the gray part of the ground) is divided into larger macroblocks, less coded codewords, and more details (tires ) The partitioned macroblocks are correspondingly smaller and more numerous, and the encoded codewords are more, which is equivalent to the key coding of the images, thereby reducing the overall code rate and correspondingly increasing the coding efficiency. At the same time, H.265's intra prediction mode supports 33 directions (H.264 supports only 8), and provides better motion compensation processing and vector prediction methods.

Repeated quality comparison tests have shown that under the same picture quality, the video size encoded by H.265 will be reduced by about 39-44% compared to H.264. Because of the quality control method, different data will have corresponding changes. The data obtained through subjective visual testing shows that the quality of H.265-encoded video can be similar to or even better than that of H.264-encoded video at a code rate reduction of 51-74%, which is essentially better than expected. The signal to noise ratio (PSNR) is better. These subjective visual test evaluation criteria cover many disciplines, including psychology and visual characteristics of the human eye. The video samples are very extensive. Although they cannot be used as final conclusions, they are very encouraging results.

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