Quote:
Originally Posted by AVspace
Is it typically okay to take the very slow preset and apply it and then to manually add my own ref frames to the preset profile? Essentially what i want to do as my goal is have the benefit of the high motion estimate settings for example "multi-hexagon" subme10 and then i want to combine that with more realistic ref/bframes like 9 ref frames and 9 bframes or something like this.
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Yes. I sometimes do it from the opposite perspective. ie starting with the Slow or Slower preset and then selecting slower motion estimation settings etc.
Quote:
Originally Posted by AVspace
Would that be a decent approach? What i want to know is if it's not a good idea to change something like this from the preset. Meaning it's usually better to change the preset rather than to change a few settings. Maybe it's at 16 ref frames for a good reason and changing it messes things up, that's what i'm trying avoid. I'm looking to take the best preset i can go with and lower just a few things like ref frames to pick up the speed efficiency to get a mix of high settings and efficiency.
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The x264 wiki suggests the point of rapidly diminishing returns is reached at around 5 ref frames.
https://en.wikibooks.org/wiki/MeGUI/x264_Settings#ref
You can check to see how many ref frames x264 actually used when you encoded with --ref 16 (if you still have MeGUI's log files), or you'll find the info under x264's "Standard Error Stream" in MeGUI's Log tab after encoding.
This is from the log of a SD encode using the Slow preset (5 ref frames) and Level 4.1 (L0 being past ref frames and L1 being future ref frames). The way I understand it, for the example below, 96.6% of P frames used 3 ref frames or less.
---[Information] [24/01/18 7:04:12 AM] x264 [info]: ref P L0: 66.8% 12.9% 13.9% 2.7% 3.2% 0.5% 0.0%
---[Information] [24/01/18 7:04:12 AM] x264 [info]: ref B L0: 92.5% 5.7% 1.3% 0.5%
---[Information] [24/01/18 7:04:12 AM] x264 [info]: ref B L1: 98.3% 1.7%
Towards the end of
this page there's an explanation as to why x264 shows 7 ref frame percentages for P frames in the example above, even though the Slow speed preset only uses --ref 5.
"The last two are the virtual duplicates produced by the way x264 implements weightp. The decoder of the produced stream won't see them; they don't take DPB (decoded picture buffer) space."
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