The difference between x264 and x265 coding techniques

H.265/HEVC's coding architecture is broadly similar to the H.264/AVC architecture, including, in-frame prediction
(Intra prediction), inter-frame prediction (inter prediction), conversion
(transform), quantization (quantization), de-block filter (deblocking filter), Entropy coding (entropy
Coding) modules, but in the HEVC coding architecture, the whole is divided into three basic units, namely: Coding units (coding UNIT,CU), predictive units (predict Unit,pu) and conversion units (transform Unit,tu).

Compared to H.264/AVC,H.265/HEVC provides a number of different tools to reduce the bitrate, in terms of coding units, each macro block (MACROBLOCK/MB) size is fixed 16x16 pixels, The H.265 encoding unit can choose from the smallest 8x8 to the largest 64x64.

At the same time, h.265 's intra-frame predictive mode supports 33 directions (only 8 are supported) and provides better motion compensation processing and vector prediction methods.

Repeated quality comparison tests have shown that, with the same image quality, the video size via h.265 encoding will be reduced by approximately 39-44% compared to H. Because of the different methods of measuring quality control, the data will change accordingly.
　　

According to the data obtained by the subjective visual test, the quality of the h.265 encoded video can be approximated or even better than that of the encoded video in the case of the rate reduction 51-74%, which is, in essence, better than the expected signal-to-noise ratio (PSNR).