2nd pass with QuEnc (and maybe other libavcodec based encoders)

[M4ST3R]

I'm a bit confused about the 2nd pass. Is it useful for a better quality or only useful to reach more closely the target bitrate?

Let me explain:
I use QuEnc for svcd with MPEG4 sources, the target bitrate is always about 2200 kbps but the output bitrate is about 100kbps lower (I know it's nothing when you encode to DVD at 8000 kbps but at 2000 kbps it's not negligeable). With the QLB matrix it's even worse. I know libavcodec's ratecontrol doesn't work very well and that it's not QuEnc's fault. So in my case the 2nd pass is not very useful, in terms of bitrate targetting, since it's always undersized. Then, at least in my case, why run a 2nd pass?

So in other words: Is a 2 pass 2280 kbps file better quality than a 1 pass 2280 kbps file?

I hope my question is clear.

[foxyshadis]

It's a more even and consistent quality; in one-pass bitrate based, some scenes will have very good quality and others quite bad. At higher bitrates the effect is negligible, but at that bitrate you'll notice it.

[M4ST3R]

Thanks for the reply.