Re: Do you always shoot weddings at 1080P/24p?
 

Chris. If you shoot interlaced what is the advantage converting to Progressive if it is then going to be interlaced again for the DVD?

Ray, Surely there will be a downscaling conversion of your HD Blu-ray spec file when Architect crunches it for a DVD.

Since posting about the 'field jitter' problem I've allowed Encore to encode my Progressive 720x50p timeline as Lower Field First (presumably that is interlaced) and now I no longer have the problem. It seems my DVD/TV set ups don't handle Progressive DVDs, even though the players are set to output Progressive and the TV indicate that they are receiving Progressive signal through HDMI. Very odd.

Re: Do you always shoot weddings at 1080P/24p?
 

Hi George

I'm shooting in HD 1080 50i and therefore the interlacing is Upper Field first...I need to resize and out to Lower Field first eventually.

If you resize (from say 1440x1080 interlaced) down to 720x576 interlaced you also resize the interlacing lines and that throws them completely out of sync...that website I showed you 100fps shows you what happens. I have basically two options with interlaced...allow the NLE to de-interlace the footage which Sony Vegas can do automatically OR de-interlace before I import the footage which I'm currently doing with Upshift. The bottom line is that if you resize HD to SD you DO need to de-interlace the footage. If you shoot progressive then, of course, it has no interlacing.

I transcode the 50i in Upshift to MPEG2 HDV at 50mbps and also allow Upshift to make it progressive...I'd actually prefer to use the Canopus HQAVI Codec but that doesn't seem to have a de-interlace facility so then I would have to tell Sony Vegas to de-interlace it.

The bottom line is that you DO need to de-interlace footage if you are going to resize it..if, of course, you are editing 1920x1080 and outputting 1920x1080 then interlacing is not affected ..only an issue with HD to SD!!! and my brides all need DVD's!!!

Chris

Re: Do you always shoot weddings at 1080P/24p?
 

Thanks Chris, that explains it to me very well. I hadn't expected my migration from SD/DV to HD to be so tortuous, it seems I'm still learning.

I have been shooting Progressive 720x50p up until recently but because of the problem I'd had as I mentioned above I have shot may last few weeks at 1920x50i. I'm shooting PAL so presumably Upper Field First (that's what Premiere shows me). I haven't been deinterlacing, and as far as I know Premiere hasn't been doing it automatically, I set an 1920x1080 interlaced project. When I send it to Encore to encode at 720x576 for DVD it is doing that as Lower Field First yet I am not seeing any scaling artifacs or interlacing lines. The only time I've seen problems has been, as I mentioned before, when I've encoded Progressive footage to a Progressive MPEG and seen 'field jitter'

Very odd.

Re: Do you always shoot weddings at 1080P/24p?
 

When a reasonable DVD player encounters progressive source flagged for pulldown, it should apply a low pass filter in the vertical direction to remove interline twitter before splitting the progressive frame into fields during playback to a tube television. This assumes you have encoded your video as progressive with soft pulldown flags and the DVD player is reasonable. On the other hand, if you encode your video using hard pulldown with 60i progressive segmented frames, the low pass filter needs to be applied before encoding. Better quality will be obtained using flags rather than hard pulldown.

Re: Do you always shoot weddings at 1080P/24p?
 

Thanks Eric, but that's gone completely over my head. How/where do I apply flags.
I either send by Dynamic Link from Premiere to Encore, or encode with Media Encoder from Premiere, nowhere have I seen reference to pull down or flags.

Incidentally the jitter problem is on LCD & LED screens not CRT. But not when played on computers or laptops.

Re: Do you always shoot weddings at 1080P/24p?
 

My guess is you currently have 60i progressive segmented frames or have connected the DVD player to the LCD using an interlaced output such as the yellow composite cable.

When 60i is played back on a DVD player to a LCD television the DVD player keeps every field and deinterlaces to 60p. This can introduce twitter unless the image has been low pass filtered in the vertical direction. When a computer plays the same footage it throws away half the fields and deinterlaces to 30p. This will not cause twitter.

Rescaling HD to SD using Premier can introduce aliasing as well as interline twitter. If you are worried about quality, I would recommend Dan Isaacs hd2sd scripts

HD to SD DVD – Best Methods | Creating Motion Graphics Blog | Blu-Ray DVD Authoring Menu | Precomposed

I'm not a Premier user so I can't comment on how to master 24p to DVD using soft pulldown flags. My recommendation would be to check your current results by inspecting the VOB files of the finished DVD with mediainfo to see if they are progressive with flags or interlaced. Perhaps someone else can give more information on Premier.

Re: Do you always shoot weddings at 1080P/24p?
 

Thanks again Eric for taking time to answer me.
I'll just point out that I'm in UK therefore I read your 60i 30fps as 50 and 25, and I'm not using 24p it is 720x50p footage.

As you'll realise I don't have the technical understanding of how the MPEG is created with flags and pull downs, but I do grasp the difference between Progressive and Interlaced.

I don't have a problem letting Premiere or Encore do the scaling and compressing to encode the HD footage for DVD, it looks fine on the computer (if a bit softer than the HD), both as a Progressive MPEG or an Interlaced one. The problem I have is when I play the Progressive one on a DVD player. The Interlaced one is absolutely rock solid but the Progressive one jitters.

Obviously I don't have access to a huge array of DVD/TV combos, both set ups I've got show it as does one that I sent out to a customer, who returned it with the complain that I describe. I sent them an Interlaced one and they are happy.

I understood that the general wisdom is to keep progressive footage in a Progressive domain throughout, but this doesn't seem to be working for me and I'd like to try and find what I'm missing.

Re: Do you always shoot weddings at 1080P/24p?
 

Mediainfo is available at

http://mediainfo.sourceforge.net/en/Download

If you author a 10 second long DVD and post the relevant VOB file from the DVD, I might be able to tell what it wrong with it. The file should be about 10 kilobytes long, so it can possibly be attached to a post.

Re: Do you always shoot weddings at 1080P/24p?
 

Many thanks Eric.

I'm rendering out a wedding at the moment so I'll do what you've suggested when it's finished and send it to you.