Re: [Avid-L2] Re: Progressive Motion Effect Rendering

On Sep 11, 2012, at 10:23 AM, Terence Curren wrote:

> In a progressive project, you are going to render out a progressive frame. In other words, field one and field two should be from the same point in time.
>
> What happens when you slow a shot down, or speed it up and it doesn't work out to full even frames? Sooner or later, you end up with a field from one frame and a field from another, or you have jerky motion. The duplicate fields, both fields etc are important in those instances.
>
> Fluidmotion (I believe) looks at both fields in the frame as one in Progressive projects. In interlaced projects it looks at each field individually.
>



First, thanks to all who have chimed-in so far.

Terry, you mention fields in a progressive project.
If it's a true progressive footage (not PsF) then there wouldn't be anything akin to fields... correct? It's just one frame.

Interestingly the v6.x Help relates that in a progressive project the Dupe Field, etc. choices will not even appear as selections (even though they do).

Here are 3 relevant entries from Avid Help:


ENTRY ONE:

Render 2-Field Motion Effect Using
These options are available for two-field media in interlaced projects only.
• Duplicated Field — <snip>
• Both Fields — <snip>
• Interpolated Field — <snip>
• VTR-Style — <snip>


ENTRY TWO:

Motion effects in progressive projects behave somewhat differently from the same effects in interlaced projects. You should be aware of the following issues when you are working with motion effects in progressive projects.
• Your Avid editing application always uses complete progressive frames to create motion effects since there are no fields in progressive material. There are no two-field rendering options available in the Motion Effect dialog box in a progressive project.

• Your Avid editing application creates motion effects by duplicating or eliminating frames to speed up or slow down the motion. Because progressive motion effects use a relatively small number of full frames per second (for example, 24 or 25), if you use speed ratios that are not integer values, you might notice minor stuttering due to unusual patterns of duplication. Select simple ratios such as 2:1 (50%), 3:1 (33%), or 4:1 (25%).

• Progressive motion effects might look slightly different from interlaced motion effects because of the way your Avid editing application handles progressive material. For more information, see Working with Effects in HD and in Progressive Frame Projects.


ENTRY THREE:

Working with Effects in HD and in Progressive Frame Projects

Many video effects work the same way regardless of the project type or video format. This topic describes several situations where effect behavior varies depending on whether a project is SD or HD, or is interlaced or progressive.
Effects Considerations for HD Projects
Effects that use square geometry automatically use the correct pixel aspect ratios. These effects include Titles, Box Wipes, and certain paint modes like Mosaic. Effects such as Color Correction, Color Effect, and Luma keys automatically use the correct color space (ITU-709 for HD).

The Safe Color Limiter effect converts from 709 to 601 color space before limiting unsafe colors, and then converts back to 709 color space. For more information, see Understanding the Safe Color Limiter Effect.
Note the following:
•
You do not need to generate 4:3 media for titles.
•
Timewarp effects use a 60p input and output format in 720p/59.94 projects.
Effects Considerations for Progressive Frame Projects
Effects in progressive frame projects are frame based rather than field based, so their normal behavior is slightly different from effects in interlaced projects. In particular, temporal artifacts might appear in some effects under certain circumstances. This topic explains when temporal artifacts might appear and suggests ways to create effects that do not show perceptible temporal artifacts.
Effects that do not involve any movement across the screen — for example, masks, Color Effects, and dissolves — always look the same in progressive projects as they do in interlaced projects.
Effects that involve movement across the screen — for example, wipes, 3D shapes, or moving titles — might look different in 24p or 25p projects from their equivalents in interlaced projects for the following reasons:
•
Because the effect uses 24 or 25 progressive frames per second (24p or 25p), motion across the screen is interpolated in 24 or 25 increments per second. (Contrast the 50 increments per second for a PAL interlaced project or the 60 increments per second for an NTSC interlaced project.) For example, the edge of a 1-second Horizontal Edge Wipe effect appears in 24 or 25 different positions across the screen. For effects of short duration in particular, this difference might be perceptible to the viewer.
•
When the 24p or 25p media is output (to the interlaced Client monitor or as a digital cut), it is interlaced again and pulldown is inserted to achieve 60 fields per second (NTSC). Your Avid editing application inserts pulldown by duplicating some of the existing frames to create the correct number of fields per second. Viewers might notice temporal artifacts created by this duplication process. This behavior is a normal result of the pulldown insertion process and is often perceptible in conventional transfers of films to video formats.

PAL output with pulldown also duplicates certain frames but is less likely to exhibit perceptible temporal artifacts since fewer frames require duplication.
Motion effects that you create in 24p or 25p projects, such as Variable Speed effects, might also look different from motion effects that you create in interlaced projects. For more information on 24p or 25p motion effects, see Considerations for Motion Effects in Progressive Projects.

For more information on how your Avid editing application handles 24p or 25p material, see Displaying 24p and 25p Media.
If an effect in a 24p or 25p project does not look completely smooth, do one or more of the following:
•
Slow down the effect.
For example, a 2-second Horizontal Edge Wipe effect, while it is still performing at the same rate (24 increments per second), moves across the screen in 48 steps. These smaller movements make the wipe appear smoother to the viewer.
•
Soften the edges of the effect.
The more the edges of the effect are blurred, the less noticeable are the movements between the increments of the effect.
•
When working with moving titles, avoid small font sizes and sharp edges.
In a moving title such as a roll, lines of small text might move less smoothly than lines of larger text.














>
>
>
> --- In Avid-L2@yahoogroups.com, Benjamin Hershleder <Ben@...> wrote:
> >
> >
> >
> > I looked for some written discussion on this topic, but didn't find any right away, so...
> > I'm checking my logic with the brains of the L2 regarding rendering motion effects & Timewarps in a Progressive project.
> >
> > 1- True or False:
> > In a progressive project, the selections for Both, Duplicated, Interpolated,
> > VTR-Style, Blended Interp, and Blended VTR are there *only* in the event
> > that you have brought in some interlaced footage.
> >
> > 2- True or False:
> > The field-based rendering methods listed above have no affect on progressive footage,
> > so you could select any of them and get the same result.
> >
> > 3- True or False:
> > Fluid Motion works the same on progressive footage as it does on interlaced (creating motion vectors and doing pixel prediction).
> >
> > TIA!
> >
> > Cheers,
> >
> > Benjamin
> > ---
> > Benjamin Hershleder
> > http://ContactBen.com
> > http://Hershleder.com
> >
> > Wear It In Post!
> > Fun T-shirts, mousepads, mugs & more
> > for Post Production Professionals
> > http://www.WearItInPost.com
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>



[Non-text portions of this message have been removed]



------------------------------------

Search the official Complete Avid-L archives at: http://archives.bengrosser.com/avid/
Yahoo! Groups Links

<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Avid-L2/

<*> Your email settings:
Individual Email | Traditional

<*> To change settings online go to:
http://groups.yahoo.com/group/Avid-L2/join
(Yahoo! ID required)

<*> To change settings via email:
Avid-L2-digest@yahoogroups.com
Avid-L2-fullfeatured@yahoogroups.com

<*> To unsubscribe from this group, send an email to:
Avid-L2-unsubscribe@yahoogroups.com

<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/