Question regarding the speed settings for H.265 10-bit encoder

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Question regarding the speed settings for H.265 10-bit encoder

Post by roundy » Thu Jan 10, 2019 12:58 am

Description of problem or question:
I'm wondering, besides encoding speed, what does changing the speed Preset in the H.265 encoder actually do? The reason I ask is because I ran a series of encodes to see if I can see a visual difference in files encoded using Slow, Medium, Fast and Faster speeds. At quick glance, I haven't noticed any great visual difference between each encode. However, I did notice a large difference in file sizes.

Slow - 1.76GB
Medium - 1.04GB
Fast - 837MB
Faster - 826.6MB

Steps to reproduce the problem (If Applicable):

These are the settings I used:
H.265 10-bit (x265)
Constant Quality: RF24
Preset: Slow, Medium, Fast, Faster (for each trial)
Peak Framerate
Tune: None
Profile: main10
Level: auto

As expected Slow was very slow. Medium was quicker. Fast and Faster didn't seem to be that much quicker than Medium. So, apart from encoding speed, can someone explain the differences in file sizes?

HandBrake version (e.g., 1.0.0):
1.2.0 (1028122200)

Operating system and version (e.g., Ubuntu 16.04 LTS, macOS 10.13 High Sierra, Windows 10 Creators Update):

MacOS 10.14.2 Mojave

HandBrake Activity Log ***required*** (see How-to get an activity log)

I'm sorry. I don't have logs available for each encode. But I did keep everything the same between trials. I simply moved the slider to change "speeds". All other settings were the same in all trials.

Code: Select all

Please replace this text with the contents of your log file between the two code tags - OR -  provide a pastebin URL in place of these 3 lines.

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Re: Question regarding the speed settings for H.265 10-bit encoder

Post by mduell » Thu Jan 10, 2019 3:05 am

Changing the preset changes the quality scale a bit.

Would need to see the requisite logs to answer any more.

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