Quality of XviD's .avi

what calculate quality of xvid's .avi (like nandub/divx3)?

:confused: :confused: :scared: :confused: :scared: :scared:

Nothing can, it's a Nandub/DivX3 only feature.

No I don't. If I'd have to guess I'd say that DivX3 stores the quantizer number it used to compress each frame in the final file and Nandub reads the quantizers and calculates a quality estimate from that. Anybody know for sure?

Hi- The DivX Quality figure from DivX 3.11 comes from 200/Ave DRF (so, if Ave DRF=3, then DivX Qual.=66.67). If you know the Ave Quant (DivX 5.02 give it to you in the Analyze.log file) in XviD, you could derive an analogous figure. So how can you figure the average quant in XviD?

I just took a look at nandub's source but I was a little lost and I couldn't found something...Well if it's 200/(Avg Quant) I can make my prog to calculate it..It already calculates the avg quant..The think that I don't get is why it's 200/(Avg Quant):p ??... Maybe someone could look the source of nandub to see it it's 200/(Avg Quant) (I don't doubt manono that this is but I want someone to tell me how he has found it :p :p ). MoonWalker

Hi- You can get very bad encodes with 100% quality. Absolutely correct. You can also force high figures with the overuse of smoothers. But for "honest" encodes I find it a useful figure to have.

InputFile.cpp Code:

Does exist an (auxiliary) image/video comparison tool like EAQUAL works with sound? Something based on ITU Radiocommunication research...

Hi- I didn't get this..If you encode a movie with quant 2 you can get bad encodes?(If I get it right) I think the point pandv was making was this: Say you have a very noisy 2 hour movie that you encode in DivX 3.11 for 1 CD at 640x272. You may wind up with a very bad looking movie with DivX Qual=30 or something like that. But if you lower the resolution to 100*xxx (as in his example), then the DivX Qual=100, every frame encoded at Quant (DRF) 2, and the result may look even worse. So, yes, in this not very realistic example the whole movie will be Quant 2 and still look like s**t.