Field Order - HD to SD??

[Chris Harding]

Hi Guys



I have a small hiccup!!

My source files are 1440x1080i M2t video which of course has the interlacing at Upper Field first. When I render the clip to MPEG2 using the DVD PAL preset I get bad interlacing lines on the TV and I suspect it's because DV video is Lower Field first!!



Can I simply render the project to DVD PAL and change the field order in "Custom" to Upper Field first???? Or what settings do you use in order to make an SD DVD?????



Thanks



Chris

[Bryan Daugherty]

I have seen that artifact too and you are correct about where it comes from.

I usually render to progressive when down-rezing and have been happy with the results.

[Bryan Daugherty]

Chris you might want to check out this thread too
http://www.dvinfo.net/conf/what-happ...d-quality.html

[Chris Harding]

Hi Bryan

Thanks for that.
What I'm doing is transcoding AVCHD files to M2t files but I leave the interlace setting as "Copy from Input" so it transcodes the files with interlacing Upper Field first. I guess I should be transcoding them with the interlace setting in Upshift set to progressive so I have progressive files on the timeline.

When I render down to MPEG 2 I can use the DVD PAL preset in Vegas (which is lower field first) as this won't be a problem as the source files will be progressive with no interlacing.

Shucks!! I was hoping that I could just change the field order on the DVD preset fro lower to upper.

I really appreciate the help..I will transcode them all again, this time as progressive files!!

Chris

[John Estcourt]

when down converting footage in vegas i.e going from 1440x1080 50i to pal sd 50i you need to set the project properties to deinterlace method 'blend fields'
if you dont do this the down conversion causes interlacing problems..i dont really understand the maths behind it but its to do with the way vegas does the down conversion.
This has nothing to do with your render settings, its just the project.
cheers john

[Chris Harding]

Hi John

Thanks to you as well!! I discovered that!!!!

I took Bryan's advice and as I'm using AVCHD transcoded to M2t via Upshift (so my computer can cope!) I just redid all the MTS files again and set the transcode interlacing to progressive...works a treat and probably works a little better than letting Vegas de-interlace the file.

Bryan, give yourself a BIG pat on the back!!! I just completed the ceremony clip from Saturday's wedding and it's perfect!! I owe you one!!!

Chris

[Bryan Daugherty]

Chris,
I am glad to help. Maybe if I ever get the time to travel you can buy me a beer and tell me about the wonders of your country in return. Australia has always been on my list on countries I hope to visit. Glad it worked out for you.

[Chris Harding]

Hi Bryan

You are always welcome if you ever get to this side of the world. Very unique scenery here but then again I have always wanted to shoot some footage of Yosemite National Park.

I actually wanted to use the original MTS files and my 'puter works fine on short clips. However give it an 18 mi8n ceremony clip and it does double backflips. The M2t files in progessive mode worked out fine!! You also have the advantage of being able to get screen caps (I use the pics for the DVD cover and disk) that don't have interlacing lines on them.

I read somewhere else that you can also just render to the DVD preset and change the field to upper as the author stated that most DVD players can handle UFF video.

Chris

[Bryan Daugherty]

I tried that once and had some weird artifacting but I have heard of many who swear by that method. In my experience it is better to just make it progressive and not risk the playback compatibility.

I too would love to see Yosemite NP, it is quite far from me but I need to make the time sometime... So many places in this wonderful world and so little time to see them all...

[Jim Snow]

When converting from HD to SD, there are conflicting issues because there is a different number of lines on each. It's best to experiment with short clips to see which looks best. The biggest problems to consider are edge blurring with motion shots and motion judder. The problems differ with the type of shot as well. Fast motion makes these problems more apparent. When there is no motion, it almost doesn't matter which method you choose.

[Chris Harding]

Hi Jim

Thanks!! I have also just found this rather useful free plugin from a Vegas user which allows you to control field order from within Vegas

http://www.fishtank.demon.co.uk/Vega...ntrol_1.03.zip

Unfortunately this having to go from HD to SD is a compromise at best, but all my clients have HD TV but no a BluRay player in site so I have no option but to go the SD route!!

Chris

[Jim Snow]

Chris, that is an interesting plug-in. Unfortunately it won't install on my computer which is running Vista 64-bit although I am running 32-bit Vegas Pro 8.0c. Is there an associated web site for this plug-in where I might be able to get more information?

- Thanks

[John Cline]

If you deinterlace your 50i or 60i material and render as progressive, you are literally throwing away half of your temporal (motion) resolution. 50 individual images (fields) per second down to 25 images per second (or 60 to 30 in NTSC land.)

Resizing from HD to SD is really quite simple and the results can look fine. The single most important parameter is under "File" > "Properties" > "Deinterlace method." It needs to be set to anything except "None." I just have mine permanently set to "Interpolate fields." Also, under "Full-resolution rendering quality" select "Best."

When resizing interlaced footage to another interlaced size, Vegas will separate even and odd lines into separate fields, resize the separated fields, then refold them by alternating lines into an interlaced image at the new size. This is exactly how it should be done and that's how Vegas does it.

When rendering to MPEG2, it doesn't really matter whether you have the rendering field order set to "Upper first" or 'Lower first." The field order is stored in the MPEG2 file's header and the DVD player will read the flag in the header and play it correctly. As long as Vegas knows the field order of the source footage (which is always "Upper first" for HDV and AVCHD) then it will encode it correctly.

For what it's worth, there is no field-order flag in the header of an AVI file. If it's a standard DV file from a DV camcorder, then Vegas assumes lower field first, a file encoded with any other codec could be upper or lower and you may have to tell Vegas specifically what the field order is.

[Chris Harding]

Hi Jim
He says he has no support for 64 bit systems at the moment!! Pity!!

Hi John

Many thanks!! OK, I am transcoding my AVCHD footage to HDV via VAAST's Upshift. The software has 3 options "Copy from Input", "Progressive" and "Interpolate"

In your opinion, would I get better results by de-interlacing the AVCHD files to "interpolate" in Upshift or would it be better to just leave them as interlaced and then let Vegas de-interlace them using it's interpolate setting????

Your opinion here would be much appreciated. Of course, I can also use the Panasonic transcoder and zap the AVCHD files straight down to DV-AVI but by using them transcoded to M2t I get a much better still image off the video which I use for DVD covers etc!!

Just for interest does the pattern on this portion of my clip (pic is below) have anything to do with the fields??? If I do a frame capture it's not there!!! but it appears in the rendered video if you leave the offending bit in (I cut it out) Ideas what causes it????

Chris

[Bryan Daugherty]

John, I hear what you are saying but it is counter to my experience with vegas. More specifically in rendering dancers shot in HDV1080i to SD. No matter how I rendered them, I ended up with comb effects on the ballerinas arms and legs when there was fast motion. I tested rendering out in progressive mode and it disappeared with no judder and I will take a soft edge over a combed edge any day.

I am pretty buried right now but when i get caught up again in few weeks I will try another test run and compare the various footage results. It is possible that I missed some small setting detail that made the difference.