First benchmarks of free x265 codec

Yesterday, MulticoreWare published in public the first alpha version of the x265 library under the GPL license. It is an open source implementation for the HEVC / H.265 standard adopted in January . Just as now there is x264 as a free implementation of H.264.

Tom's Hardware Edition conducted x265 and x264 comparative tests , which showed very encouraging results.

The x265 library code is still very raw, only x86 is supported, there is no B-frame support for maximum compression, and some optimizations inherent in x264 are missing.
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Despite all this, the test results show a very good increase in quality / bitrate compared to x264.

During testing on the Core i7-4770K, the following command was used:

x265 --input Kimono1_1920x1080_24.yuv --width 1920 --height 1080 --rate 24 -f 240 -o q24_Kimono1.out --rect --max-merge 1 --hash 1 --wpp --gops 4 --tu-intra-depth 1 --tu-inter-depth 2 --no-tskip 

with quantization parameters (QP) from 24 to 42.



The results show that x265 benefits most from using the SSE3 instruction set, and then SSE4.1. At the same time, the gains from AVX and AVX2 are relatively small.

The x265 developers hope to achieve a 1080p30 coding rate in real time on a Xeon server with 16 cores next month. Well, for now, on a quad-core Core i7-4770K, they show about 3 FPS.



Finally, the most important thing is comparing x265 and x264. As the tests showed, the new codec shows 25-35% better compression at the same quality level.



As an option, with the same bit rate, you can get a better picture quality on x265 than on x264.