CRF Question

[Beak]

I have just installed a Bluray burner in my machine.

I have a 36 Gig m2ts file that has to shrink to 23 total.

I am hoping someone could suggest a CRF number that will get me around 20 gigs plus/minus.

I am hoping to avoid the time 2 pass encoding take as I have a fair number of filters slowing me down.

Any help would be appreciated.

[Sharc]

As you can read from many posts in this forum it is pointless to expect a certain file size by selecting a certain CRF - not even approximate. For a given CRF the file size depends on the complexity of the pictures (motion, details, noise, your filters, etc) and will accordingly vary significantly.
If you want a certain size you need to go for 2-pass.

[sneaker_ger]

or 1 pass ABR

[Beak]

The bitrate calculator has made a CRF estimate that seems OK. I realize it will miss the target size if the movie is complex but its working well so far,

I'll try ABR at a bitrate of 20900. That should hit the filesize and seems to be a good enough bitrate to ensure good quality.

Thanks to those who helped.

[Groucho2004]

I'll try ABR at a bitrate of 20900.
Don't.

Also, the time you need to figure out the correct CRF value for your target size is probably longer than a good old 2 pass encode.

[blubb444]

If you're really using an extremely slow script (for example QTGMC at "placebo" on a 1080i source) then you might consider to first encode your script to lossless (for example --preset fast --qp 0, you can of course use faster presets too) and then run a 2-pass on that file.