HD to SD conversion using avisynth

[nijsheepdogs]

I am creating a DVD and I have HD 50p footage that I have exported losslessly from Premiere Pro using the lagarith codec. I am quite new to avisynth but I came across this script on here and it seems to give me pretty good results. I was hoping you guys might help me tweak it a little!

AviSource("source.avi")
ConvertToYV12()
Spline36Resize(720,576)
Blur(0,0.5)
ColorMatrix(mode="Rec.709->Rec.601",clamp=0)
AssumeTFF().SeparateFields().SelectEvery(4, 0, 3).Weave()

I am still getting a bit of horizontal line flickering. Is the best way to combat this turning the blur up from 0.5? Are there any other filters I could apply to help with the process from HD to SD?

Also, my DVD is going to be replicated, I'm just wondering what the highest bitrate is I can get away with? I'm currently using a max of 9Mb/s but I've seen lots of debate about going higher. I don't want to compromise its compatibility with older players. THANKS!

[LMotlow]

Blur before resizing, not after. Blur(0.3, 0.2) would work, but you should experiment. Sometimes an anti-aliasing filter like Santiag might be needed before resize, or after. It depends on the video. If sharpening is needed (not always), do it after resizing.

9Mb/s max should be plenty, but remember that the total max includes audio bits, too. The max rule when older players were around was ~8Mbps.

I think the term is "line twitter", not "line flicker".

[nijsheepdogs]

Blur before resizing, not after. Blur(0.3, 0.2) would work, but you should experiment. Sometimes an anti-aliasing filter like Santiag might be needed before resize, or after. It depends on the video. If sharpening is needed (not always), do it after resizing.

9Mb/s max should be plenty, but remember that the total max includes audio bits, too. The max rule when older players were around was ~8Mbps.

I think the term is "line twitter", not "line flicker".

Great! Thank you for your response, I'll experiment and see what works! What would I need to add to my script for sharpening?

[Cornucopia]

You shouldn't need to blur at all - the resizing does add a form of blurring anyway (well, depending upon which algorithm you use).
Also, IIWY, I'd only change to YV12 near the end (after the downsize) - you want the color channel to be as accurate as possible before it is fixed as subsampled, and downsizing after subsampling will mess it up further.

So I would try changing it to:

BlahBlahSource ("MyFile.vid").AssumeFPS ("pal_double")
Spline36Resize (720,576)
#Blur (0,0.5) - if necessary
ColorMatrix (mode="Rec.709->Rec.601",clamp=0)
AssumeTFF().SeparateFields().SelectEvery(4, 0, 3).Weave()
#Sharpen(blah, blah) - only if really necessary

Scott