Aha, yes, both your tips did the trick, as I was indeed going from 50p to 25p exact. I guess that disabling the resampling is the easiest way when no time-stretching or speed alteration is intended, otherwise I suppose resampling should be kept enabled, which is where your other trick comes into play. Except that then no benefit is accrued in terms of the source's original time resolution because the Vegas project literally sees the source media as if it was half its original framerate.

I did also try altering the Blending/Interpolation (deinterlacing) setting in Project properties (as I said in my first post), but it made no discernable difference.

I did a "Help" on "Resampling" and apparently it's intended primarily at least for the opposite condition - where the source framerate is lower than that of the project. Would be good if Vegas's engine knew better when not to apply it.

Thanks for the tips though. So now if I use an EX3 to shoot 720 50p with a view to making a 50i DVD but then also want a 25p render to make a web video (say), I could avoid a blurry web video by using these tips. Or could I ... (read on)...

BUT ... Wait a minute though - I just looked more closely at the frames on the Preview of a test 50i Project fed by 50p fmedia, and ... I see ... no interlace lines. It instead looks like I expected the 25p result to look, i.e. pure image - no interlace lines or ghosting. Could there be a further workaround lurking here? Like render as 50i then twiddle something to fool the file into thinking it's progressive?

There is also a problem here: 50p->50i doesn't work as expected. Bummer for that EX3 720 50i (or presumably 60i) mode, as recommended in general when deliverable is a standard DVD.

I asked a while ago http://www.sonycreativesoftware.com/forums/ShowMessage.asp?Forum=4&MessageID=616320 whether a 50i Vegas project would take advantage of simply using alternate lines in alternate frames of a 50p source and the answer then was that that indeed is what it ought to do. But since I just tested this and can't see any interlace lines in the Preview, now I'm not so sure it actually does... Again, I tried playing withInterpolate/Blend settings but they made no difference.

Looks like 50p may be a weak area for Vegas, 8.0c at least. Haven't installed v9 as I'm mid-project(s). Anyone know if it does any different? Or if 60p->60i does the same (in Vegas) as 50p->50i ? or if any other NLEs do it right?

I've done one shoot in 720p50 with my EX1. It is difficult to get Vegas to play nicely.
I just went back to this, it was a rushed job and I basically just did things until I got a decent looking output, never the way I like to work.
Revisiting the 720p50 footage this is what I did:

1) Create a 720x576 50p project, no de-interlace method. Drop 1280x720 50p footage into that, disable resampling of the footage,
2) Create a 50i widescreen project. Nest project 1 into that.

Render out and check. I believe I'm seeing correct interlacing. I need to check on a CRT as last time Vegas managed to get the field order reversed, nasty but easy enough to fix.

There is a fundamental problem though which starts at the camera. To get correct 50i you need to turn the shutter off to get a shutter speed of 1/50 otherwise your footage will look a bit Saving Private Ryan. Problem then is if you also want to extract slomo you'll have too much motion blur. Well that was my thinking when I first did this job.

After revisiting this I'm not 100% certain at all. I've shot quite a bit of 50i with the EX1 at 1/100 shutter speed by mistake in the early days and I do not recall it ever look as juddery as what this 50i footage from 720p50 looks. To be 100% certain we need to do some controlled tests. I need to rig up something moving at a fixed speed and shoot it at both 50p and 50i. We should be able to get identical results out of Vegas.

Bob.

Bob,

The coments of Simon Wyndham http://forums.dvdoctor.net/showthread.php?t=47557 bear out our thoughts on what ought to be happening on the camera->NLE pipeline. He says FCP treats 50p like 25p i.e. misses out every other frame. As you suggest, he says it looks fine as long as the shutter was off during shooting. Also he says if you put it onto a 50i timeline you get smooth footage. That is subjective of course, so I will now do an experiment on FCP to see if the expected interlace lines can be seen there (on a progressive display).

FCP experiment was not practical to get done in lunch hour as I hoped (partly down to my limited experience/understanding of it).

However, interestingly, I found that FCP's HD and ProRes format settings include 25p, 30p and even 60p but not 50p. Only their HDV format includes 50p. Tried that and it was accepted. However the field precedence setting was fixed at "None" and greyed-out, so I couldn't just set it to 50i as was the whole point of this experiment, to see if the interlacing would be generated correctly by FCP (alternate fields from alternate frames).

An unexpected twist: Preview sometimes misleads (even in Best/Full).

I put some 50p media into a 50i project. Set the Preview mode to Best/Full. Stepped through individual frames (25 fps) in Vegas. Especially studied frames where there was significant jerky motion. No interlace lines (combing) seen. I assumed in my earlier post that this meant Vegas was not generating interlaced footage with the required 1/50 second interval fields. Now it seems that was an illusion - only in the Preview - the rendered result IS interlaced (and looks about right).

I discovered this when I rendered the same project out to HuffYuv and also to DV, in both cases as PAL 50i LFF. Playing in VLC and in VirtualDub, they DID exhibit combing. So WYSIWYG does not apply here it seems.

Finally, I imported both the same HuffYuv and DV renders back into the same 50i project. As always with HuffYuv, which doesn't seem to carry this info (as confirmed in GSpot), I had to tell it that it was interlaced. On the other hand the DV media properties already confirmed it was interlaced. As for the original project preview, when played in Vegas, no interlacing lines were seen.

Presumably the Preview process (for internal window and for external device) or else some other process upstream of it is doing some (unexpected and unwanted, by me) deinterlacing, either deliberately or accidentally.

Previewing from Vegas onto my progressive external monitor did the same. The Preview Device option for "Apply deinterlace filter" was disabled. No change when the Project's "Deinterlace method" was set to None.

Next, now that I don't trust the Preview anymore, ran a test to confirm that the "Disable resampling" fix (for generating 50p->25p) worked not only when previewing but also when rendered to 25p. It did - no ghosting seen whether the rendered file was played in Vegas or VLC.

So WYSISWYG ("Sometimes").

"An unexpected twist: Preview sometimes misleads (even in Best/Full)."

You need to switch off Scale To Fit to have a chance of seeing interlaced footage correctly i.e. with the interlace combing displayed as it is. Nothing beats a good CRT monitor of course but even they or the device feeding them can deceive.

Bob.

Aha yes that was it - so simple - Doh! Thanks Bob. WYSIWYG once more.

Sorry All for raising a "red herring" about the 50p->50i, and mighty glad it does work correctly after all. Still leaves the issue of 50p->25p of course.

Bob wrote:

"1) Create a 720x576 50p project, no de-interlace method. Drop 1280x720 50p footage into that, disable resampling of the footage, "

This doesn't work for me, Bob:

- at project 2 output, I'm getting black frame around the widescreen PAL picture
- I see a dramatic loss of sharpness

With the above, I'm not even bothering to check whether interlacing is correct. ... What am I missing?

I know what I was missing :)

At stage 1), you need to create a WIDESCREEN 720x576 50p project, no de-interlace method, and drop 1280x720 50p footage into that, disable resampling of the footage.

Now all id fine - I'm getting properly interlaced and sharp PAL DVD stream in step 2).