Quality RF levels

[AppleFanBoy]

Hi all,

Bit of a noob question so be gentle! When encoding films in handbrake I always aim for a bitrate of 10Mbps. Most films can achieve this without needing to move the RF number above 24, some need it pushing to 26, but on a few I've noticed that I have to go as high as 30.

Anything beyond 26 seems to become really noticeable to my eye, so my question is, if I have two films that have been encoded to 10Mbps, one done at RF24 and looks great, and the other was done at RF30 and looks terrible, why is that? Is it simply because the source file was a higher bitrate on the RF30 and compressing it down to 10Mbps is just too much? Or is there anything I can do in Handbrake to improve things?

[Legendarion]

If you put the mouse-cursor somewhere around the slider, you'll get a window that kind of explain some of the reason.

Look here: https://i.postimg.cc/DZPjd3Rn/RF.jpg

[AppleFanBoy]

I understand how the slider works, my question is why would 2 films where the end result is 10Mbps yield one that looks great (RF24) and one that looks terrible (RF30) - they're both 10Mbps so they should look equally good quality?

[rollin_eng]

It doesn’t really work like that.

Some films will require more bits to look good and some will require less.

That’s why you should not really worry about bit rate, just pick a quality that looks good to you, say RF 24, and let the encoder pick how many bits it wants.

[JohnAStebbins]

To expand on rollin_eng's response a little... The bitrate necessary to achieve a certain quality depends on the complexity of the video being encoded. A black frame that never changes will require very low bitrate. A scene with a lot of detail and fast motion will require a hight bitrate. Most video is a combination of scenes of varying complexity and bitrate will vary drastically from scene to scene when using constant quality RF encoding.