progressive/interlace and settings on vegas (newbie)

[Federico Perale]

excuse my ignorance but I haven't figured out one thing...I guess it should be general knowledge but go easy...still new

1) if I shoot interlaced (say with a Z1), do I always need to specifiy a deinterlace method in Vegas, and if so do I need to specify it on the project properties AND on the rendering options? and which field order should I use?

2) if I shoot progressive (say with an EX1), if by mistake I selected a deinterlacing option in Vegas what's the issue on the final video? is there any reason why I would want to interlace a video that was originally progressive?

3) and finally, what If I decide to shoot interlaced, and leave it interlaced? this way (I guess) I am relying on the TV or whatever viewing device, for instance, to do the deinterlacing....
any pro and cons to create a progressive or interlaced output video?

I came to think about this by watching some interlaced raw files using the VLC player: unless I specified to "automatically" deinterlace if needed, the footage showed some lines and it wasn't pleasant.

[David Johns]

Generally speaking, if you're rendering to a format for viewing on a computer, then render it progressive, 'cos that's what computers display. If you're going to burn a DVD or other broadcast formats, leave it interlaced.

If you are going to deinterlace then there is only one place to set the *method*, which is in the project properties window (choice of blend or interpolate fields).

If your source is progressive and you select a deinterlacing option, it won't make any difference.

Don't forget also you will need to switch your bit-range from 16-235 (for broadcast aka 'studio RGB') to 0-255 (for 'computer RGB'); there's a filter on Vegas for that.

Regards
Dave

[Federico Perale]

Originally Posted by David Johns

Generally speaking, if you're rendering to a format for viewing on a computer, then render it progressive, 'cos that's what computers display. If you're going to burn a DVD or other broadcast formats, leave it interlaced.

If you are going to deinterlace then there is only one place to set the *method*, which is in the project properties window (choice of blend or interpolate fields).

If your source is progressive and you select a deinterlacing option, it won't make any difference.

Don't forget also you will need to switch your bit-range from 16-235 (for broadcast aka 'studio RGB') to 0-255 (for 'computer RGB'); there's a filter on Vegas for that.

Regards
Dave

thanks David...what's the best choice for deinterlacing and field order?

[Jeff Harper]

For television shoot interlaced and don't touch any settings in post, leave it interlaced.

[David Johns]

Originally Posted by Federico Perale

thanks David...what's the best choice for deinterlacing and field order?

I think I have it set to 'blend' but the real answer is try both on a section of your footage and see which looks best for you!

As for field order, that's only relevant when you're messing about with interlacing and frankly, I'd leave it exactly as it is on your source footage (which Vegas will pick up if you set the project properties to match the source footage)

Cheers
Dave

[Craig Longman]

The field order really is dependent on your source.

You seem to be in London, and a betting man would think the UK. So I'll mention what I know about both NTSC and PAL.

In NTSC, it's normally even or lower field first, (2nd, 4th, etc) and for PAL it's normally odd or upper field first (1st, 3rd, etc).

As pointed out though, I think this is gleamed correctly from your footage, assuming you're using a region correct video camera.

If you're planning on making a DVD of your stuff, then just leave it interlaced as is. You might notice some combing on the preview on your computer unless you're using an interlaced preview device, but it will be correct when burnt to DVD. If the combing is way too distracting, you can change the project to progressive, but remember, remember, remember to turn it off again before you render, if you're rendering to an interlaced medium.

And an important *** on the comment about adding a sRGB (studio) to cRGB (computer) filter. If you are using a computer monitor to preview, that will render the blacks and whites correctly. It is useful if you're doing any colour correcting or grading, etc. But you HAVE TO remember to disable it or remove it from the preview before you render. The same codec that decoded sRGB expects sRGB when it's encoding. And a DVD will definitely want sRGB, regardless of the region/format.

Hope that helps.

[Randall Leong]

Originally Posted by Craig Longman

The field order really is dependent on your source.

You seem to be in London, and a betting man would think the UK. So I'll mention what I know about both NTSC and PAL.

In NTSC, it's normally even or lower field first, (2nd, 4th, etc) and for PAL it's normally odd or upper field first (1st, 3rd, etc).

Actually, in NTSC, it also depends on whether the video is in 480i or 1080i. What you stated above is true - for 480i or 576i (standard definition). However, standalone DVD recorders and some other interlaced MPEG standard-definition recording devices use odd or upper field first. All 1080i video, even in NTSC countries, use odd/upper field first. (Remember, ATSC chose to use PAL instead of NTSC for the field order in interlaced high-definition broadcasts.)

[David Johns]

Originally Posted by Craig Longman

And an important *** on the comment about adding a sRGB (studio) to cRGB (computer) filter. If you are using a computer monitor to preview, that will render the blacks and whites correctly. It is useful if you're doing any colour correcting or grading, etc. But you HAVE TO remember to disable it or remove it from the preview before you render. The same codec that decoded sRGB expects sRGB when it's encoding. And a DVD will definitely want sRGB, regardless of the region/format.

Yes, unless you are rendering to a computer format for display on a computer such as Windows Media Video, in which case leave the filter on. Thus a video which is ingested is in sRGB, gets decoded within Vegas, is expanded to cRGB by the filter and then encoded by WMV correctly for computer display (in cRGB). If you are rendering back to the same video codec the footage was recorded in eg DV to DV, then sure, turn it off.

See http://www.glennchan.info/articles/v...lorspaces.html for a comprehensive description of the issue (and the other Vegas articles on that site too)

Dave

[Craig Longman]

@David
I have scoured Glenn's information and many others, the sRGB/cRGB thing is a real pain. The OP had been talking about interlaced though, so I assumed non AVI. But the more places link to Glenn's information, the better. It should be required Vegas reading I think.

But, if your computer project is to be put up on YouTube, you should leave it encoding sRGB, as YouTube seems to do a sRGB->cRGB conversion no matter what.

@Randall
But HDTV isn't still considered NTSC is it? And all that 720i/p & 1080i/p, isn't that all HDTV? I guess I never really thought about it, but I'd figured we'd stop using that acronym =)

[Randall Leong]

Originally Posted by Craig Longman

@Randall
But HDTV isn't still considered NTSC is it? And all that 720i/p & 1080i/p, isn't that all HDTV? I guess I never really thought about it, but I'd figured we'd stop using that acronym =)

Sorry I got confused by this. Regarding only standard-definition interlaced video, for NTSC it is normally even/lower field first (analog broadcast signals and DV digital video are always even/lower field first in NTSC). But some NTSC-compatible standard definition devices such as some digital camcorders and DVD recorders record odd/upper field first.

480p video has no field order - and if the frame rate exceeds 30 fps, it would be considered "enhanced definition" rather than "standard definition".

[David Johns]

Originally Posted by Craig Longman

But, if your computer project is to be put up on YouTube, you should leave it encoding sRGB, as YouTube seems to do a sRGB->cRGB conversion no matter what.

It does? Bugger, I didn't know that. Thank you. So presumably if you upload a full-range 0-255 cRGB file, any values 0-15 or 236-255 get clipped? I must do some trials...

Cheers
Dave

[Craig Longman]

Originally Posted by David Johns

It does? Bugger, I didn't know that. Thank you. So presumably if you upload a full-range 0-255 cRGB file, any values 0-15 or 236-255 get clipped? I must do some trials...

That's what I've read. I've only just almost finished a full suite of testing I'm doing to figure out aspect ratio's and PARs with YouTube, then I was going to investigate that. Here is a video on YouTube, the individual who posted it seems technically knowledgeable, I've read some of his posts on other forums. It has two grey ramps, one marked sRGB, one marked cRGB. It clearly shows detail loss with the cRGB in white especially (makes sense, as you're losing almost 8% there as opposed to only less than 6% on black).

I'm a bit cloudy on a few details about how he made the video (was it rendered at sRGB or cRGB?), but however he did it, it sounds like it would be typical of what the crushing would be:

YouTube - YoutubeTest.m2t

[David Johns]

I've done a little set of RGB tests of my own and it seems you're right. Interestingly (if you're into this kind of thing) when I first uploaded the .wmv version, the blacks still appeared crushed but you could distinctly see the 235-255 range. That has now vanished - presumably as part of YouTube's post-processing which it applies after the clip is initially put online...

YouTube - UKAirscape's Channel

Regards
Dave

[Craig Longman]

Hey David, yeah... one of the things to keep in mind with YouTube.

Also, in case you missed this thread, is a link to someone's page dealing with how it handles 1080 footage. It isn't good news... =)

http://www.dvinfo.net/forum/what-hap...ml#post1565699

[Larry Reavis]

getting back to the deinterlace question . . . there's no trick in changing progressive to interlaced (just set the render settings to interlaced), but it's not so easy getting progressive for the web out of interlaced - and most cams still yield interlaced video.

A foolproof method follows:

1. Set Project Properties to 59... frames per second, best rendering quality, interlace set to None, 1920x1080 (presuming that you are starting with 1920x1080i).

2. Download Mike Crash's free Smart Deinterlace.

3. Use Smart Deinterlace effects on media (go into the media window and right-click, or right-click on the FX button on any event and choose the source file for the Smart Deinterlace). In order to avoid artifacts, you should right-click on the clip, click Properties, then clear the checkmark for Smart Resample.

4. In the Smart Deinterlace FX window, choose “field” preset. In clip properties, set resampling to “none.” Motion Threshold: 5. Choose cubic, and motion denoiser.

5. Or, if you have an entire track on the timeline that has many interlaced clips, you can do them all at once by clicking on the track FX button; but there is a trick: You must go down to the bottom of the Smart Deinterlace FX window where it says "Smart Deinterlace" and make sure that the little triangle at the far left points to the left; if pointing to the right, click it once to make it point left. (You won't need to worry about this if you apply Smart Deinterlace to individual clips in the Project Media Window instead of to the track.)

Then render out with Cineform using Progressive setting. Result: No judder, no comb, no loss of resolution.

Please note that Smart Deinterlace works only in 32-bit versions of Vegas. That being the case, I always deinterlace each individual clip and render it using Cineform in 9c-32 before putting it on the TL of my project. That way, I can edit the TL with its Cineform clips with Vegas 8c, the most stable version of Vegas that I've found for editing, but then render in 9e-64, the most foolproof rendering version.