While the maximum data volume of 8K SHV video amounts to 144 Gbps, the transmission capacity of the current HDTV terrestrial digital broadcasting is only about 14 Mbps per channel, which is not enough to transmit 8K SHV video. It is necessary to compress the video signals as much as possible.
 Neighboring pixels or pixels of temporally-adjacent frames have almost the same values in many cases, which is called redundancy. The video compression technology aims at minimizing the redundancy to decrease the data volume.
 Human eyes have a tendency not to detect some level of distortion of complicated texture in a video signal. Also, their sensitivity about fast-moving objects is lower than that about stationary objects. Taking advantage of these characteristics, video signals are compressed within the range of distortion that human eyes can not notice.
 The current major compression scheme consists of 4 types of processing: temporal, spatial, quantization and code allocation. These basic technologies are the same either for 8K SHV or the current HDTV digital broadcasting.
【1】Temporal processing
 Videos of temporally-adjacent frames are very similar; so, if a frame that has been transmitted is stored in the receiver side, only the difference can be sent in the next frame transmission to decode the signals. But, simply calculating the difference between frames is inefficient as the difference is not small when there are moving objects in the video. Therefore, each frame is partitioned into blocks (e.g. 16 x 16 pixels) and the motion between frames is estimated for each block. This is called motion estimation/motion compensation (below drawing).
【 Motion estimation / Motion compensation 】
【2】Spatial processing
 A pixel being similar to neighboring pixels means that, if a video signal is considered as a waveform, the change of waveform is small. In other words, video signals are concentrated on the lower frequency. To make use of this frequency disparity for efficient compression, video signals are converted into frequency domain signals.
 The process of converting a frequency domain signal to another value is called quantization. For example, if the signals in the range of 0-255 are converted to the range of 0-127, the amount of signals will be halved. Human eyes tend not to notice some level of distortion of complicated texture (high frequency). So, high-frequency signals are quantized coarsely while low-frequency signals are quantized finely to achieve efficient compression.
【4】Code allocation
 Quantized signals are eventually outputted as digital signals of 0 or 1 code. During the process, different codes are assigned according to the frequency of occurrence: shorter codes for common information and longer codes for rare information. Thus, the total amount of signals is reduced.
 8K SHV broadcasting employs the latest video compression scheme HEVC/H.265, which has about 4 times the compression efficiency of MPEG-2 used in the current terrestrial digital broadcasting. It enables compression of 8K SHV signals into 100 Mbps or less for broadcasting.
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