Video encoders are actually very different from video encoding and decoding standards. Video encoders are a code implementation of video encoding and decoding standards. However, different implementations of the same algorithm have significant differences in performance and efficiency. The main differences between video encoders can be divided into the following aspects:
1) Support for compression tools in video encoding and decoding standards
2) Optimization for video encoding speed
3) Optimization for video encoding quality
4) Scalability of functionality and code
5) Commercial vs. Free
For example, some people believe that HEVC encoders are definitely stronger than H.264 encoders, but we know that there are many different prediction directions in HEVC. If I design an encoder that does not use inter frame prediction but only intra frame prediction, and regardless of the content, uses this fixed mode for encoding, then the resulting stream can be imagined to have poor prediction performance and very low compression efficiency. Although the bit rate is high and the quality is poor, this stream may still comply with HEVC standards.
Relatively speaking, if H.264 is used for encoding, but the optimization of the entire encoder is done very well, and the overall bit rate control is optimized to a very excellent level, then the quality of the video stream encoded by this H.264 encoder can be better than that of the HEVC encoder. In the field of video encoding and decoding, when a new standard is just released, people will not quickly adopt this new standard's encoding scheme because the optimization of the encoder end has not been done properly. Therefore, simply considering the performance of the encoder and its support for this standard is a very one-sided approach. Therefore, in practical work, when choosing an encoder, one must not blindly believe that the H.265 encoder is necessarily better than the H.264 encoder. This is not necessarily true, and sometimes even some relatively low standards can be done well.
Therefore, when choosing an encoder, one should start from the differences between the video encoders mentioned above.