Compressed Too Small?

[OutOfBreath]

Hi there,

I'm quite new to video compression and am just seeking some advice on weather I am 'doing it right'.

In the past I have always just ripped my bluray movies straight to an ISO using clown_bd. No re-encoding. However hard drive space is becoming an issue and I don't want to have huge amounts of drives to manage.

I've been using handbrake to compress the main movie down to an .mkv file. The results look great but I'm a little worried about the file sizes I am getting.... they seem too small.

My settings in handbrake are the 'High Profile' setting with a constant quality of 18, passthu audio and 1920x1080 resolution...

I was expecting a 2 hour movie to compress to around 10-15GB.... but I am getting much smaller than that.

For example:

Lord of the rings: Fellowship of the ring (3hrs): 10GB (from 40 for the main movie iso)
Kung Fu Panda (1.5hrs): 3.4GB (from 18GB for the main movie iso)

As I said... these look great, but I am a little concerned that in the future I will discover that they are too compressed if I upgrade my TV..

Do you guys think these settings are ok? Should I be concerned about the file sizes?

Thanks for any help.

Paul

[aedipuss]

for 1080 i shoot for about 10mbps or in file size that's about 5GB/hr. my lotr fotr backup is 15GB for the normal version and 17GB for the extended.

your idea of an ok rip may be different.

[OutOfBreath]

When you say that you aim for 10mbs... that's pretty much what I was expecting.

I thought that using the constant quality options were better than using the target bitrate options these days though. And from what I have read a RF of 18 is transparent to most people... but this is giving me a bitrate much lower - more like 6Mbps

[dragonkeeper]

When you say that you aim for 10mbs... that's pretty much what I was expecting.

I thought that using the constant quality options were better than using the target bitrate options these days though. And from what I have read a RF of 18 is transparent to most people... but this is giving me a bitrate much lower - more like 6Mbps

I use 18 CRF all the time but i don't get encodes that small for 1080P. By chance are you using the deniose filter, i couldn't imagine it would increase compressibility that much but for movies where grain may have been added intentionally it's possible.

[OutOfBreath]

Nope, all filters are off under the filters tab.

Watching the bitrate while playing LOTR it seems to jump between 4Mbps and about 11Mbps.

[jagabo]

CRF 18 will lose a little low contrast small details. If you zoom in and look at still frames it will be pretty obvious. It will also show up as posterization artifacts in dark areas, visible at normal playback speed. You can step down to lower CRF values if you think you may not be happy with CRF 18. Try 15. Even 12. But at 12 you probably won't get much compression over the raw Blu-ray rip. Using x264's Grain tuning might help too.