Comparing quality

[Zarxrax]

Sorry if this is a dumb question, I tried searching, but wasn't really sure what words to search for.
I am wondering how I can find out the average psnr and the average quantizer of a video. Also are these methods usefull for comparing quality between different codecs? I try comparing codecs by looking at them, but it just all looks mostly the same to me.

[Kyo]

With debugview from sysinternals you can get the "debug" info for xvid and at the end of the 2nd pass it will report de average quant, for psnr i have no clue.

[ultimatebilly]

Try this command-line utility...

http://vsofts.com/codec/codec_psnr.html

[yaz]

Originally posted by Zarxrax
Sorry if this is a dumb question, I tried searching, but wasn't really sure what words to search for.
I am wondering how I can find out the average psnr and the average quantizer of a video. Also are these methods usefull for comparing quality between different codecs? I try comparing codecs by looking at them, but it just all looks mostly the same to me.

the average quant can be easily calculated from the statfile (see threads on compressibility check).
from debugview output u can also get the quant distribution.
u can visualize quantizers with ffdshow osd function.

snr/psnr: use the appropriate avisynth filter for that!

the bests
y

[majerle]

or easyly try http://www.geocities.com/analyzerDRF/

open your file and watch the analisys.

bye

[Tommy Carrot]

The only reliable way to compare them is your own eyes. Higher PSNR is not always better visually, the artificial quality checking methods are often give false result.

One easy checking method: Start 2 Virtualdub, open the 2 encoding (or the source and the encoding), place the 2 virtualdub to the same position in your desktop, seek to the same frames with both, and with ALT+TAB you can switch between them instantly. The differences are very obvious with this method.

[Zarxrax]

Well, I've always done comparisons exactly like that, but I dont trust my own eyes enough to really get anything out of it. I often see *differences* between clips, but thats all I can tell, they are different. I can't really say which one really appears better, most of the time.

[Valky]

Originally posted by majerle
or easyly try http://www.geocities.com/analyzerDRF/

open your file and watch the analisys.

bye

This software seems very interesting..I already tried that with several different files and with older Divx movies the scenes looked very crappy where the program told me that Quant's were above 6.

I just dont get it why it cant show all my movies, or why it tells me on some movies that there are 50 dropped frames..

It also detected some really bad colour smearings on certain frames on one of my futurama encoding where I didn't even know they exist. But there they were..