VP9 vs x264

[darkman85]

Hello Everyone,

I was wondering if anyone knows the approximate relation between bitrate and quality(even though it is subjective) for x264 vs VP9 encoders at low bitrates, 400-900 kbps and 480p resolution videos.

I understand VP9 is better. But how much?

Thanks in advance.

[KarMa]

Generally about half in the low bitrate scenarios. There is no right or wrong answer for these types of questions even though they get asked all the time. If you use x264 with the best settings and VP9 with the fastest/worst settings then the gap gets narrow.

[fornit]

With respect to bitrate and quality VP9 is more comparable to x265 than to x264.

You'll get acceptable results for 480p at a bitrate of 650 kbps (or lower) with VP9. It also offers a bitrate mode named "constrained quality" (see https://trac.ffmpeg.org/wiki/Encode/VP9). This is something not available in x264 or x265. It is a mixture of crf and 2pass abr encoding.

On the other hand:
- VP9 encoding is much slower than x264 (and also slower than x265) -> that's the biggest disadvantage and probably the reason why it's not used by many sites
- Documentation is poor as it's not used that often
- It's not supported by IOS
- It's less stable than x264, tending to produce problems where x264 works fine

[Gravitator]

The problem with VP9 is megablock blurring of objects (grass and foliage is converted into a large green square).