[HELP] Loss of x264 options when selecting a preset

[The_Tinkerer]

I've always just glossed over this, finally it's bugged me enough to ask about it.

In Hybrid, load any video, go to the x264 tab, and select "constant rate factor (1-pass)" for encoding mode.

The x264 command line looks like:

x264 --preset veryfast --crf 18.00 --profile high --level 4.1 --ref 3 --direct auto --b-adapt 0 --sync-lookahead 15 --qcomp 0.5 --rc-lookahead 40 --qpmax 51 --partitions i4x4,p8x8,b8x8 --no-fast-pskip --subme 5 --aq-mode 2 --vbv-maxrate 62500 --vbv-bufsize 78125 --sar 1:1 --qpfile GENERATED_QP_FILE --non-deterministic --demuxer raw --input-res 1312x960 --input-csp i420 --input-range tv --input-depth 8 --fps 25/1 --output-depth 8 --output "C:\Users\Administrator\AppData\Local\Temp\Lossless.264" -

Now, click the arrow next to "Preset", in my case I use veryslow. The command line changes to:

x264 --preset veryslow --crf 18.00 --profile high --level 4.1 --ref 6 --sync-lookahead 1 --qpmax 51 --vbv-maxrate 62500 --vbv-bufsize 78125 --sar 1:1 --qpfile GENERATED_QP_FILE --non-deterministic --demuxer raw --input-res 1312x960 --input-csp i420 --input-range tv --input-depth 8 --fps 25/1 --output-depth 8 --output "C:\Users\Administrator\AppData\Local\Temp\Lossless.264" -

So, the following command line options have been completely eliminated:

--direct auto
--b-adapt 0
--qcomp 0.5
--rc-lookahead 40
--partitions i4x4,p8x8,b8x8
--no-fast-pskip
--subme 5
--aq-mode 2

Is that by design, or a bug? It's been like that for quite a long time.

Video files seem to look and play fine... so I'm not sure how important this is. 

[Selur]

Okay, here's what's happening when applying the 'very slow' preset (slightly simplified).

• Hybrid applies the 'default/medium'-preset (since all other presets are based on it).
  
• Hybrid applies the specific changes of the 'very slow' preset, that differ from the 'medium/default'-preset:
  
  --b-adapt 2 --bframes 8 --direct auto --me umh --merange 24 --partitions all --ref 16 --subme 10 --trellis 2 --rc-lookahead 60
• assuming 'x264->Misc->Main->Minimize command line' is enabled, which is the default, Hybrid then:
  • checks which preset best covers the current option
    
  • replaces these option with the '--preset <presetName>'
    
  • check whether the rest of the parameters are covered by a tune option, if a tune option fully overlaps with the remaining parameters (doesn't usually happen), then hide those parameters by replacing them with '--tune <name of the found option>
    
  • hides all options which are covered by the 'medium/default' preset which do not interfere with the previously selected preset and/or tune option.
    

-> If you want to see the full x264 command line and don't want those simplifications of the commandline parameters simply disable 'x264->Misc->Main->Minimize command line'.

The options you are 'missing' are simply changed to the application of the preset. Applying a preset in x264 differs from applying a tune option, it always means applying the 'default/medium'-preset and then applying the additional changes of the selected preset. (This is how the x264 developers, same for x265, designed it; this is not a Hybrid thing. )

I hope this explains what happens to the options you thing are going missing.

Cu Selur

[The_Tinkerer]

Thanks very much for the explanation.