Some questions (VBR anomoly and field order "waves"

[mbellot]

I'm not sure if this should be newbie or advanced, but it seems somewhat technical to me so... Please move it to newbie if its more appropriate there.

I am working on converting some old VHS stuff to DVD via my miniDV camcorder (Canon ZR40) and have run across a very odd thing.

I am (for now, until I get the process refined) just reading in the DV files, making a Premiere project to "splice" them all back together (its about 2 hours of content), frameserve out of Premiere @ full D1 720x480 res. with Videotools Server 0.93 into CCE. CCE is set up for 3 pass VBR 2000 min, 4500 avg, 9000 max.

After encoding I happened to use bitrate viewer to check the file and found something odd. Bitrate viewer reports the average bitrate @ 3454 instead of ~ 4500 set in CCE (max is only 7021, but I assume it never needed full bitrate).

Does this mean my file only really needs ~ 3500 for the average bitrate? Or does bitrate viewer calculate bitrate differently?

On a different matter, I can't seem to get decent looking encodes with CCE unless I set Premiere up for "No Fields" and then configure CCE for progressive frames + zigzag scan order. If I try to set the field order up (since DV is bottom field first) in Premiere and CCE I end up with wavy looking I frames (what I assume reversed scan order encodes look like). It doesn't seem to matter what combination I use, they all look messed up (except No Fileds/Progressive).

Anyone have any suggestions?

Thanks!

Mark

[AceYu]

After encoding I happened to use bitrate viewer to check the file and found something odd. Bitrate viewer reports the average bitrate @ 3454 instead of ~ 4500 set in CCE (max is only 7021, but I assume it never needed full bitrate).

Average bit rates are only that an average or target rate, yes you could get away with a lower rate but if it works go with it. the fact it is lower indicates your sceens are not very complex or moving much.

As for the field problem it really depends what is happening from the VHS to DV stage, your camera may be recording it as a progressive scan picture.

Later Brett[/quote]

[mbellot]

Ace,

Thanks for the info. The video is somewhat complex, but it moves fairly slow. There are a few instantaneous blips in "motion" because there is a flash camera going off from time to time. I just assumed that if you set an average bit rate, you would get it...

Just as an experiment I loaded up TMPGEnc. It's "wizard" analyzed the AVI file being frameserved out of Premiere and identifies it as bottom field first (even though I had left "no fields" selected in the export settings). I then encoded a small section (one of the really bad spots with CCE) using similiar settings (except had to do two pass instead of three).

The video came out clean with no weird interlace artifacts, but the picture quality just wasn't as nice. Bitrate viewer agreed, the Q levels were higher (8 average, 11 max vs 5 average, 7 max for CCE).

Mark