h265: different bitrate for same CRF in Avidemux and Virtualdub

[Vovan]

Hi,

I found out that the same CRF produces different bitrate while using x265vfw in Virtualdub and HEVC (x265) in Avidemux.
For instance CRF 28 yields 1.5 higher bitrate in Avidemux than in Virtualdub. For the same result CRF 31 should be used in Avidemux.

So which converter (if any) produces result really corresponding to CRF 28?
Is there any standard test video file to check compression?

Thanks.

[poisondeathray]

It also depends on the snapshot of which x265 version (maybe one is older), and the settings used.

Maybe you used different settings, different version, or maybe you have different colorspace or preprocessing


You can also check the settings and versions used with mediainfo (view=>text)

[Vovan]

Well, I found what happens - by default HEVC (x265) in Avidemux uses ultrafast preset, while x265vfw uses medium.
So I unchecked "Use advanced configuration" and choose "medium", like in Virtualdub.