A nasty progressive vs. PsF surprise...

megabit wrote on 10/14/2012, 7:52 AM

Using Vegas for 5 years now, I've always dealt with 1080/25p material; of course being really in the Progressive Segmented Frame format for the 50i compatibility reasons. My projects have always been set to 25p; my renders - to either 25p (for PC or Internet playback), or 50i (for DVD and/or BD delivery). Never had problems with that; Vegas has been smart enough to never display interlacing artifacts (jagged lines) even though my projects are always set to Deinterlace Method= NONE...

For some reason I had the project set to 50i, UFF, when I dropped some AVCHD clip from my FS100 onto Vegas timeline. It played back perfectly until I split it - following that, only the first part (from Record Beginning) is playing like progressive should! All the remaining chunks of the split clip show the dreaded jagged lines!

Of course this is no problem at all, as - after changing the project properties to Progressive - all is fine again. But it does rise the question:

- could it be that some proper flags are only present and visible at the beginning of original clips, but NOT in all the parts that the given clip is cut into?

I'm looking forward to all explanation proposals;

Piotr

Comments

farss wrote on 10/14/2012, 2:47 PM

What you've had happen is certainly possible if Vegas makes a cut between frames. That causes a field cadence error which is different to a field order error. At least one camera historically had a bug in this area just to add to the confusion but I think that was fixed.

The way to ensure this cannot happen with Vegas is to ensure your PsF footage is seen by Vegas a Progressive i.e. the media is flagged as such in media properties. Now if it is and Vegas is still somehow able to get it messed up then we have a bug and a very nasty one.

Bob.

megabit wrote on 10/14/2012, 3:27 PM

I should have added, Bob, that all the clips resulting from splitting a progressive one still ARE progressive in their properties, and yet - with the project set to 50i - they are treated as described...

So - do we have a bug?

Piotr

PS. The same behavior in 11 and 12, BTW.

Rory Cooper wrote on 10/15/2012, 1:53 AM

I had this issue before but not on all the events on the timeline where it appears to switch prog/interl so I had to render those clips separate with TMPGEnc
deinterlace to get it right. Only had this issue with Canon Vixia AVCHD cams footage. Vegas 09 can’t recall it happening in 10

farss wrote on 10/15/2012, 3:53 AM

"So - do we have a bug?"

It certainly sounds like one to me. Just how you go about describing it and reporting it to SCS I haven't a clue.

Bob.

megabit wrote on 10/15/2012, 5:21 AM

Bob,

Do you mean a camera/format bug, or a Vegas bug?

I'm asking because I've just checked the same scenario with EX1 footage, and nothing like this happens. So it looks like it's AVCHD in general, or its flavor specific to the FS100, which is to blame...

Piotr

PS. Which was the camera model with the same issue that you mentioned earlier?

farss wrote on 10/15/2012, 5:41 AM

"Do you mean a camera/format bug, or a Vegas bug?"

I'm inclined towards a Vegas bug.

"I'm asking because I've just checked the same scenario with EX1 footage, and nothing like this happens. So it looks like it's the AVCHD in general, or its flavor specific to the FS100, which is to blame..."

I'm trying to get my head around all of this and the difference between field order and field cadence but my brain is just not working as it should.

What should happen is:

Fields 1a,1b;2a,2b;3a,3b can be merged to give frames 1;2;3 and it doesn't matter if "a" is upper or lower.
Now if a cut is made between say 2a and 2b you can see that 2b,3a become merged into a frame from two fields that do have temporal separation and it's all a mess.
So maybe if the camera wrongly records 1b,2a;2b,3a;3b,4a etc wierd things can happen but I'm not 100% certain about this.

"Which was the camera model with the same issue that you mentioned earlier? "

I think it was the HVX200 but the problem was fixed in the production models.

I'll try to see if I can borrow our FS100 and run some tests but don't hold your breath as I'm pretty snowed under.

Bob.

Rainer wrote on 10/15/2012, 11:41 PM

My experience is the same as Rory Cooper's above. I get the occasional 25 psF clip from a Canon HFS10 that once loaded into Vegas shows jaggies and overlapping fields. Not every clip, not a display issue, renders out the same way. You could blame the camera, except it only happens in Vegas (10 and 12), looks fine in Windows Media Player and other NLE's. I'm inclined to think there's a nasty bug in the way Vegas is interpreting PsF AVCHD footage: You can download a one frame screen dump from https://dl.dropbox.com/u/96106037/jump.jpg or the full one minute clip at https://dl.dropbox.com/u/96106037/00017.MTS if you are interested.