Filtering newbie

[Losko]

Hi, I use to encode my movies using x265 for space saving and I've read sometimes pre-filtering may raise content compressibility, now I can play with avisynth but I'm a total newbie at filtering.
First of all:

1. does more compressibility mean the same content may be encoded faster?
2. does more compressibility mean the same content may be encoded in a smaller size?

And then:

1. where will I find some readings for a beginner?
2. any suggestion for not going through trial and error?

Thank you for any hints.

[birdie]

1. depends on the source and your filters but if the source becomes less noisy then encoding might be faster though I guess less than 10% faster
2. surely

1. First read about noise patterns, then you may try googling for appropriate filters
2. This really depends on your source which might be a lot different than what others have posted on the net, so trialing might be a necessity. To save time you could take one clip, and encode a short part of it using different filters/filters parameters/encoding settings. If you're content with the results, you can proceed to encode the entire clip.

[Forteen88]

I recommend TemporalDegrain2 (in AvisynthPlus) for high-quality denoising.
I normally use,
TemporalDegrain2(grainLevel=false)

grainLevel, if input noise level is relatively low set this to false. This setting must be left enabled if disabling it increases the output noise level while all other settings are at default.

[StainlessS]

When encoding, noise looks like detail to encoder, and so it has to try hard to retain the false detail and so larger less compressable result.
Denoise, produces smaller, and less nasty results, some on-site prefer a little noise, I'm not too keen on noise at all.
I like McDegrainSharp() with default settings [in avisynth], although the sharpening will not produce quite as dramatic a reduction in size,
so can just use McDegrain if better compression required. Many prefer TemporalDegrain2, I'll have to try it one day.
Also Limiter() after any denoise will eliminate out of TV_Levels range color components with further reduction in size likely.