Does 'keyint infinite' improve overall compression with crf and mb-tree?

Question

After reading what intra-refresh does, I kinda got confused. I'm encoding for YouTube and YouTube will re-encode the video-file anyways, so I thought "why not removing all these heavy IDR-frames?" I just want to compress my video as hard as possible, enabling everything that could help me getting a lower filesize, but still maintaining a high quality.

I used to test around stuff with lossless QP encoding, but the only thing I could max out was the merange. Here is a paste of my x264 settings: Pastebin.

I want to achieve highest compression while maintaining visually lossless quality. (using crf values around 10 - 13, and merange 32)

Could anyone give me advice on how to compress my video super hard (without touching the crf value!). I also want to know if it's true, that keyint infinite reduces overall compression.

Answer 1

To tell you the truth you're wasting your time. Just use --crf, --preset, and possibly --tune. The presets were made by the developers so users won't have to monkey with bewildering combinations of options, and overriding the preset options is not recommended unless you know what you're doing. I'm sure you would get a similar response at the #x264 IRC channel. The general usage is:

1. Use the slowest preset you have patience for (and placebo is considered a joke as it is a complete waste of time and helps at most ~1% compared to veryslow at a very high time tradeoff). See x264 --fullhelp for a list of available --preset and --tune options.

2. Use the highest CRF value that still gives you an acceptable quality. 10-13 is probably overkill unless you are using 10-bit x264, but you gave no indication of this. The CRF values of 8-bit and 10-bit x264 are not "equal" in terms of visual quality last I checked. Can you tell a difference between 13 and 18?

3. Use these settings for the rest of your videos.