Low quality AVIs to Mpeg/DVD - best settings?

[Gibson's Squares]

I've got a bunch of PAL resolution Xvid AVIs, with a video bitrate of around 1200kbps.

It's pretty fast moving footage, so as you can imagine gets a bit blocky quite often.


I need to author a DVD/DVDs out of them, which means converting to Mpeg-2, and I'm wondering what bitrate/settings I should use so as not to compress them in a way which will make them worse, but also not bloat the files any more than necessary?

[manono]

Do quality-based encodes? That way the sizes will become whatever they have to be for the quality you want. No bloating.

And if they're blocky already, maybe you'll want to do something about that first.

[sanlyn]

Without first cleaning low-quality sources, encoders won't make them look better. Encoding and noise cleanup are two different processes.

[Gibson's Squares]

I'm not after making them look better, I'm just wondering what sort of Mpeg bitrate will give me a 'like for like' copy?

[manono]

It won't be 'like-for-like' in any event since MPEG-2 is a lossy codec. But your sources are already so degraded it won't make much difference. Anyway, to answer your question, there's absolutely no way to tell with bitrate-based encoding. As I suggested before, do a quality-based encode. Did you even tell us which encoder you're using?

[jagabo]

8000+ kbps

[AlanHK]

With a low quality source, using HCenc with 2 passes, increasing MPEG bitrate over 2500 is probably not going to ge a noticeably better result.

You can use Avisynth filters to mitigate blockiness and other problems first.
You need to sharpen after DeBlocking (which inevitably blurs the image).

e.g.

... source ...
DeBlock_DeBlock(quant=25, aOffset=8, bOffset=16)
UnsharpMask(42,11, 0)

Use AvsP to adjust the filter settings.

[jagabo]

You can use Xvid's built in deblocker and deringer filters.

[Selur]

@AalnHK: is DeBlock_Deblock a typo and it should be DeBlock_QED ? if not, please post a link to the script or the script itself.
Thanks

[AlanHK]

@AalnHK: is DeBlock_Deblock a typo and it should be DeBlock_QED ? if not, please post a link to the script or the script itself.
Thanks

I just grabbed an old script I had used a deblock in as an example and that was the first I found.

Probably just "Deblock()" would work, but that's the format AvsP uses, denoting it comes from Deblock.dll.
It's from Manao & Fizick: http://avisynth.org.ru/mvtools/deblock.html

[Gibson's Squares]

Cool, thanks for info guys.

[Selur]

@AlanHK: Thanks for clearing that up, I know Deblock for Manao & Fizick, but I prefer DeBlock_QED. I just was surprised by the DeBlock_Deblock syntax. (probably because I don't use AvsP)