Bug-Progressive Render isn't always Progressive

Bill Ravens wrote on 9/25/2007, 4:12 PM
I just spent the last two days tearing my hair out over the production of a DVD that kept giving me horrible flickering, even with the "reduce interlace flicker" option. I'm using Vegas Pro8.

Process: I started with 1280x720 progressive still images. I was maintaining progressive frame mode through the entire workflow, capture from a progressive HDV source, to Cineform Intermediate, to progressive mpeg2 for DVDA. I began checking the "details" of the rendered file in Project Media Window. The file details would sometimes indicate "lower field order" even if I had selected "Progressive" in my render selection type. Other times it would indicate "Progressive", but I kept seeing combing(vertical artifacts) in the final file.

Diagnosis: The problem with incorrect frame field output happened whenever I selected various forms of 720x480 sizes, either by selecting NTSC DV Frame Size or by selecting "Use Project Settings".(Project settins were set to 720x480 progressive) It happened when generating the Cineform Intermediate. I also tried PicVideo Intermediate, with the same lower field order result. The final workaround to get a progressive field output was to select HDV 720p and change the frame size to 720x480.

I finally produced a flicker free DVD by checking each intermediate video stream to ensure it was progressive.

Comments

GlennChan wrote on 9/25/2007, 8:17 PM
Not sure if this fixes things, but the render settings override the project settings.
Bill Ravens wrote on 9/25/2007, 8:59 PM
'fraid not. Render settings override unless one selects "use project settings". Even so, my problem was first noticed when render settings were for progressive and I was getting interlaced.

My guess is that the interlaced settings are (erroneously) tied to the 720x480 settings.
DJPadre wrote on 9/25/2007, 10:16 PM
could it be that as your in NTSC land, progressive is still seen as 60i due to pulldown ?
here in aus, the differential is easy to segregate so pulldown is done without thinking, but as the HDV stream is still in 60i, vegas still sees 60i, until you remove the pulldown manually or through preferences.
It may still be progressive, however its transported in an interlaced stream... this is how progressive works unless your working with Native off a HVX
TimTyler wrote on 9/25/2007, 11:41 PM
Bill,

Why were you working with 720x480 at all?

Capture 720p HDV, work in a 720p HD timeline, and then finally render to NTSC MPEG.
Bill Ravens wrote on 9/26/2007, 6:26 AM
DJ....

Yeah, I'll concede that this may be more a "feature" than a bug. If Vegas simulates true progressive by having two identical fields, then this is the issue. My intent is to reduce the interlace flickering, which is quite bad since I started with still images. I was able to eliminate the flickering by ensuring I stayed with progressive throughout my workflow. This meant using the PicVideo mjpeg as an intermediate instead of the cineform intermediate.

Tim...

Good question. My input was 16:9 format, which appears with letterboxing on my 4:3 monitor. The mpeg2 conversion would add pillarboxing in the conversion to 4:3. This results in a final image that doesn't use the full available height of a 4:3 monitor. In order to ensure I wasn't letterboxing/pillarboxing, I converted the image format to 720x480. I wanted to keep the HDV format as long as possible during the editting phase, in order to keep my resolution as high as possible.
TimTyler wrote on 9/26/2007, 7:36 AM
Bill,

You understand that 720p is NOT 720x480 progressive, right?

It's 1280x720.

All HD (and HDV) is 16:9. It's just part of the spec. If you want to finish in 4:3 SD, it would probably be better to render a HD master of your finished project, and then render that HD master to a pan-n-scanned/cropped 4:3 sub-master.
Bill Ravens wrote on 9/26/2007, 8:30 AM
Tim...regardless of the workflow, that doesn't negate the fact that there's something amiss in Vegas.

I thank you for the lesson in the diff between 480i and 720p. That's very old news, I'm afraid. Perhaps we should be asking the Vegas Media people if they know the diff.
BigBadBz wrote on 12/11/2007, 6:41 PM
Folks:

Sorry to dredge up an old issue, but I'm running into this tonight as I take my first shots at moving from Vegas 6 to 8 Pro. I'm sure I'll feel like a DOOFUS, but I don't see where I can do this:

Render settings override unless one selects "use project settings".
farss wrote on 12/11/2007, 10:40 PM
I've struck a similar issue with HDV and 25p, except the final washup was that HDV doesn't support 25p, only 25PsF which is why I had to do a merry dance with Vegas and in the end discover that the VCR spat the dummy anyway.

I suspect you might have hit the same wall. The DVD spec only supports 24p but not many devices will display 24p SD so the player outputs 60i anyway and you can be right back where you started from.
I've done a few commercial DVDs from HiRes stills and spent a lot of time dealing with major problems of line twitter, while this is a product of interlacing it's not because the footage is interlaced as such, even progressive footage will exhibit this when displayed on an interlaced display. The only fix that's 100% certain to work is to reduce the vertical resolution, anything over around 450 lines in PAL land with content that contains horizontals lines at that res and you have a problem.

One interesting test is to use VLC to view the footage and change the de-interlace method of PsF footage, it can be a bit of an eye opener.

Bob.
Udi wrote on 12/12/2007, 12:47 AM
The Mpeg2 - DVDA 24p NTSC template uses "23.976 + 2-3 pull down" (see it in the custome video tab).
Maybe you should change is to 23.976 without the pull down.
The HDV 720p template is actually 30p - did you change it to 23.976 ?

Udi