Compressibility? What EXACTLY does it mean?

[travisbell]

Hey guys, I am sorta confused by the compressibility percentage.

Lets take an example rip of mine,

Source: HDTV source, AC3 audio, 29.970 fps, ~50 mins.
AuoGK Settings: fixed 960 width, AC3 audio, set size of 875MB

Compressibility comes in at 68%. Is that good? Would it be better if it was 52% or 88%? I don't get it...

Thanks!

[Sharktooth]

Compressibility is based on encoding the source at Quant2 and estabilishing a percentage of compression based on the final file size.
The higher the compressibility value the better the source compresses (the quant2 encoded file is smaller) so a low compressibility is a "bad" thing...

[travisbell]

OK, so it doesn't have anything to do with your settings, but strictly just how well the source compresses. So if we expand on that, a source that compresses better will need less bitrate to look good than a source that doesn't compress very well.

Got it! Thanks man.

[niamh]

You got that perfectly right, except that it does change with different settings as well. Some filters and codec settings can augment or diminish the compressibility.

[Cynric]

so what does a compressibility of over 100% then mean?? got some of those...

[Teegedeck]

Edit: I see now that you asked that in another thread (http://forum.doom9.org/showthread.php?s=&postid=622788). Let's keep it together. I answered in your thread.