Reduce resolution or reduce crf?

[sacharja]

Hello,

I wondered what gives a better quality in general. Would you reduce the resolution to play the movie with an overlay and postprocessing afterwards or would you rather reduce the crf/bitrate?

Let's assume a 720p as source material here.

[Snowknight26]

Reducing the CRF and bitrate are essentially opposites.

[Koorogi]

Your goal is to reduce the bitrate/filesize? Then your choices are really:

1) Reduce bitrate
2) Reduce bitrate and resolution

It should be obvious that the second one will result in better quality, because there is less data to encode in the same number of bits. But if the quality you get after just reducing the bitrate is good enough for you, then you can skip the resolution reduction.

[sacharja]

Reducing the CRF and bitrate are essentially opposites.
I formulated it badly.

What ensures a better quality:
reducing the resolution or reducing quality (either by crf or bitrate).

@Koorogi
you're right it's clear for bitrate encoding, but what about crf?

Here's an example:
I encode the 720p mpg movie as q=26 and afterwards I see that the file is too big. There are two things I can do: I can reencode the movie with 640x360 and q=26 and maximize it while playing back. Or I can reencode it with 720p and q=35 (or whatever high value that produces a similar file size).

[Ranguvar]

Two things. First, the relationship of bitrate to resolution has been discussed before. There's a recent thread in this forum talking about it. The summary is, it depends on the source, method of resizing, and your personal preference. Encode a small sample to ways or something.

Second, you say the file is too big? If you need file size, use 2-pass.