HD to SD DVD aliasing issues

[Ernie Santella]

All the files on the my mac monitors and thru my Kona card look absolutely perfect. The DVD made from the HD-to-Compressor-DVDSP-DVD, played back on a stand-alone NTSC monitor look crappy.

The DVD’s out of DVDSP made from an HD dragged into SD timeline to Compressor-DVDSP-DVD look perfect.

Thanks guys for the help, keep the questions coming, we’ll figure it out.

Yes, I know “why not just do the HD-SD conversion and be done with it. I will, but I want to know why for future HD projects that I have to make client DVD’s.

[Jeremy Garchow]

[Ernie Santella] “I want to know why for future HD projects that I have to make client DVD’s. “

Totally.

Now, if you open the MPEG2 file created by Compressor in Quicktime, what does it look like? Aliasing?

[Ernie Santella]

“Now, if you open the MPEG2 file created by Compressor in Quicktime, what does it look like? Aliasing?”

Nope. Clean as a whistle. So, that seems to eliminate something funky going on in Compressor. But, that’s looking at it on a progressive-scan MAC 30″ monitor.

It seems the issue is when DVDSP makes the DVD, then it looks bad.

[Jeremy Garchow]

[Ernie Santella] “It seems the issue is when DVDSP makes the DVD, then it looks bad. “

Not so fast. The Mpeg2 file just gets rewrapped with audio and burned to disk with programming pointing to the file. Basically a pass through and no further compression.

Tell me about how your dvd is hooked up to your tv and is there a progressive switch or setting on your DVD PLAYER? What kind of tv?

Jeremy

[Ernie Santella]

My DVD player is hooked up by Composite to my pro JVC SD 19″ monitor.

Again, I do not see the alaising issue with DVD’s created from the HD down-converted to SD, then thru compressor timelines. Only the DVD’s created directly from the 720p to Compressor timelines. That’s the crazy part.

And again, any DVD’s made from 8-Bit Uncompressed SD sources look fine on the same DVD player/monitor. It’s just this silly 720p timeline.

[Jeremy Garchow]

[Ernie Santella] “Only the DVD’s created directly from the 720p to Compressor timelines. That’s the crazy part. “

But the MPEG2 (m2vs) of BOTH scenarios look clean in quicktime, right?

[Ernie Santella] “It’s just this silly 720p timeline. “

Which is a different media origination of 8 bit SD.

Do you have a progressive switch on the outside of your player (might be around back) or a progressive setting in the menus of your DVD player?

[Gary Adcock]

[Ernie Santella] “That’s seems dumb, that they don’t make a 720p30 setting? “

720p30 like 720p24 are NOT real formats according to SMPTE.
720p 50/60 is the format.

AJA does make a 720p30 setting- but because of the rarity of its use it is part of the additional setups

maybe you need to look a little harder.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Inside look at the IoHD

[Ernie Santella]

So, Gary, what do you use when you are editing 720p footage shot at 30fps? The 720p/60 or the ProRes/30 compressor settings?

What’s the downside to using the stock 720p/60 setting with 30fps material?

[Sean Oneil]

I have two theories.

One is that you have 30fps footage, but you’re editing in a 60fps sequence. When you export and MPEG directly via compressor, the Pro Apps assume it is 60fps, so it 60i MPEG. While that shouldn’t matter since the footage is only 30, it could be causing the field order to be wrong. Hence your problem. Try a 730p30 sequence like everyone here mentioned.

Another possibility is that Compressor is creating a progressive scan 30p MPEG. While I believe this allowed for the DVD spec, I think it is uncommon (and pointless). This leaves it up to the DVD player to interlace the video itself during playback. And maybe your particular DVD player isn’t very good at doing this. The easiest way to check if your MPEGs are 30p is to import it into Final Cut, look at it in the FCP Browser window, scroll over to “Field Dominance” and see if it says Upper, Lower, or None. If it says “None”, then Quicktime (and ultimately DVDSP) assumes it’s progressive-scan and is authoring the DVD accordingly. This would explain why it looks fine on your computer, but not after you’ve burned a disc.

Sean

[Gary Adcock]

[Ernie Santella] “So, Gary, what do you use when you are editing 720p footage shot at 30fps?”

I never never use or shoot 30fps except for slight slo-mo, sorry ernie

My content is always acquired at 24 /25 – I have no need for video frame rates, except when I output– it is just not my shooting or editing style.

I like the filmic look and people come to me for that look.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Inside look at the IoHD