Compressibility definition ?

How is defined compressibility of a movie ? I read about it many times, having rough idea what it is, but in spite of many searches have never found its definition. BTW I cannot force forum to search by AND logic.(now, worked before I think) Even "+A +B" and "A AND B" gives results "ORed" according to result page.

Well I guess one definition would be the size per a given quant. So a compressible movie will have a smaller size per quant, giving you a lower average quant for a set size. A movie that is hard to compress will be larget per quant and as such require a large size/bitrate to hit the same average quant as the compressable movie.

Exactly what I meant. Too many higher/lower, smaller/larger's in one paragraph.

I understand quite well, what compressibility is about. But it should be independent on file size, so does liquid density measuring is independent on volume of measuring bottle. What e.g. means compressibility is 60 % ? It should be dependent on movie properties only ( by strict given test procedure) and independent on testing subject ( = me and what I am going to do with a clip ).

I don`t think there is a strict definition of compressibility. There are too much parameters involved. It depends not only on the source, but on the format (MPEG2, MPEG4 ASP or AVC or something completely different for example wavelet based formats like snow or dirac), the used encoder and its algorithms and the used settings.

CompCheck vs Average Bitrate 

Don't know about your guys but I still have my doubts about the reliability of the Compcheck, after all it only checks portions of the source with real fast scenes changes, in not like an full analysis as on some transcorders like Shrink which checks the whole source before transcoding to the desired size/quality. Right now I'm kind of leaning to-wards the idea of finding the average bitrate of the source and give a percentage of that rate to the encoder to work on. Since I'm a 1-Pass encode freak(don't care much about a target size), I been trying different methods lately like fixed Q-Based encodes and fixed bitrate encodes with an 20% of the average bitrate from the source which is calculated by using ReMPEG2 on a single VOB file, and so far the results are very good but I still have to tweak some XVID settings to see which one gives the best results.

Edit: Reply to Kopernikus In fact, I do not need it, neither others do. I just like things are called by their proper names and not to like the opposite. There is many ways how to measure compresibility. It is just about agreement/consensus which is used when people talk about that. And it is not rocket science. I have not written anything about 2 full Encodings at all. I fact if I do some tests I use Code: