Constant Quantization (CQ) in TMPGenc?

[Madseason]

Okay, it's been a while since I've done an encode. I used to encode 2 pass VBR but decided to give Constant Quality (CQ) a try since, after googling around, I found some that said Constant Quantization could yield better picture quality. Here is one example:
http://tangentsoft.net/video/mpeg/enc-modes.html

So, would I be correct in assuming that the CQ slider in TMPGenc will give a WORSE picture the closer the setting is to 100? Is there any secret to this setting or should I just experiment? Thanks in advance to whoever can clarify this.

[junkmalle]

CQ = Constant Quality in TMPGEnc. The higher the value the higher the quality, the bigger the file.

You could have figured this out in a few seconds just by encoding a few frames at different settings and looking at the results.

[Madseason]

junkmalle
PostPosted: May 17, 2005 18:20
CQ = Constant Quality in TMPGEnc. The higher the value the higher the quality, the bigger the file.

Yeah, the pop-up says that and I did do that test but I wasn't sure if setting it at 100 would give a better picture just because the filesize is as well and... TMPGenc's documentation leaves much to be desired. CQ is one of the VBR modes and with other encoders, the lower the Q setting, the better the overall image quality. I'm not sure how TMP handles it in this regard...that was my question. It would seem that setting it at 100 in TMP would be more akin to doing a CBR encode with less bit redistribution at both ends, staying closer to the average, and thus, creating a larger file. I was just wondering if there were any experts in using CQ mode out there that could provide more insight into this.

[Madseason]

Alright, I feel like the village idiot here. TMPGenc presents it as CQ constant quality which means the higher the setting, the lower the Q value (contrary to what I read on some sites). Sorry, I had been using CCE and it's been a long time but I came back to TMP since it has smoother output and doesn't add noise. Sorry, and Thanks!

[junkmalle]

In TMPGEnc I usually use a CQ value between 80 and 90. At 90 it's pretty hard to see any difference between the output and the source.

[Madseason]

Alright Junkmalle, thanks for responding. Do you leave the average, max, and min at the defaults? Well, I'll give it a go with your settings and see how it works out. Thanks much!

[junkmalle]

Do you leave the average, max, and min at the defaults?

There is no average setting in CQ mode. I leave the max and min at their defaults (8000 and 1000) when making files for DVD. You're limited at the top end to ~10000 kbps total (for audio and video) and some players have trouble with writable media when you're at the max, so 8000 is a fair compromise. And in the past I've had problems with very low minimums (on SVCD) so I usually go with min set to 1000.