GOP structures for VCD

[AwesomeDude]

Right, bear with me on this one as I only vaguely know what I'm talking about. I recently discovered this GOP thing and I'm hearing a lot of talk on the net that if you optimise or edit the standard structure that you can acheive higher quality VCD's. Does anyone know know anytrhing at all about this?

Also, if somebody could give me any general tips regarding filters or whatever I can do to squeeze a bit more quality from a DVD to VCD rip I would be HUGELY grateful. I usuallly rip the vobs with DVD Decrypter, create a D2v with the DEFAULT SETTINGS for DVD2AVI 1.76 (i only change a couple of audio settings, encode to wave, 48khz to 44khz etc), load the d2v and wav into tmpgenc and then with motion search precision set to highest quality (what exactly isa this by the way), I encode.

Thanks in advance.

[bugster]

For some info on Motion Search in Tmpgenc, read this thread .

As far as changing GOPS to Improve quality in VCD, I doubt it. You can change the GOP in order to fit a little more playing time on a VCD by using less frequent I-Frames, but this will generally lead to a loss in quality.

Perhaps what you are looking for can be found at www.kvcd.net, this is the kind of thing those guys mess with all the time. Beware though, if you want to use the forums it is $2.99 to register!

[AwesomeDude]

Thanks dude, that was a great help.

[animatron]

Perhaps what you are looking for can be found at www.kvcd.net, this is the kind of thing those guys mess with all the time.

That was a very long time ago! They now use a maximum GOP size of 24 frames on kvcds, and kdvds are kept at a standard size of 15 for PAL and 18 for NTSC.
http://www.kvcd.net/portal/articles.php?lng=en&pg=20

Beware though, if you want to use the forums it is $2.99 to register!

It's well worth it!

As for AwesomeDude's question, if you use CBR, the longer the GOP the worse the quality.
Longer GOPs are usefull only on VBR encodings.