What is 'Object Content'?

terrypin wrote on 6/29/2012, 2:39 AM

In all these years of MEP usage I've never used the Object Trimmer (hit Q while an object is selected). I'm now trying to understand it a little.

For a start, what is the meaning of the number 'Object Content'? From its name I'd have assumed it would show the number of frames in the object, but clearly not. (The hovered pop-up explanation given doesn't enlighten me.)

https://dl.dropbox.com/u/4019461/MEP-ObjTrim-1.jpg

With fade-in/out both set to 0.5 sec (displayed as 13 frames), here are the numbers I see for various object lengths:

1s: 61 (as shown in the example)
2s: 49
3s: 36
4s: 23

Also, while we're into this sort of detail stuff, it's always seemed obvious that you cannot manually set an object's fade-in or fade-out to say 12.5 frames (0.5 s in my usual projects). Yet when I use Set transition length to set 1 s for a transition between two adjacent objects and then use full zoom to examine either of the objects, I see that the marker has been set to a position half way through a frame. But if you try to drag it, it always jumps to the end of a frame, and can never be returned to a mid-position.

And, given that frame rates can be set to just about anything, I'd have expected that the Object Trimmer would therefore show frames to one or two decimal places. Yet even 12.5 is shown as 13 in my example. Any insights into all of this would be much appreciated please.

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Terry, East Grinstead, UK

Comments

johnebaker wrote on 6/29/2012, 4:41 PM

Hi Terry

If you hover your mouse over the left or right arrow next to the numbers it tells you what they do .

As to the frames issue this may be a bug as you cannot have half a frame MEP appears to work in full frames only which makes sense when you consider that a movie is just a series of still images in which the moving subject is in a slightly different position for each image being sequenced quick enough to fool the eye into thinking the content is moving.

John

terrypin wrote on 6/30/2012, 1:55 AM

Thanks John. Well, I'll have another stab at understanding it, but as I said that hovered explanation didn't do anything for me first time round! So, the 'object content' isn't referriing to the object currently selected, but the object on either side, if any?

But what do the numbers in my example actually mean? Take this very simple example of two 2 s (50 frame) JPGs alongside weach other with no transition. What is '25' telling me?

https://dl.dropbox.com/u/4019461/MEP-ObjTrim-2.jpg

Re the partial frame topic, I think you're right. Although it's an odd sort of bug because it gives you the 'correct' result that intuitively you might expect!

Coming at it from a different angle, when you tell MEP to make a fade of exactly 1 s total between two adjacent objects, what result do you expect? 12+13? 13+12? 12.5+12.5? Or (and I think there's evidence that this is what it actually does), 13+13?

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Terry, East Grinstead, UK

Scenestealer wrote on 6/30/2012, 3:09 AM

Hi there Terry

I think that "Object Content" is only meaningful if you have an object in place that has been trimmed from something longer. The figure shows you the number of frames you have trimmed off and that are available to extend the contents of the clip, if you want to increase the crossfade or move the hard cut without moving anything down stream. If you use an untrimmed clip then this figure will be 0 and clicking the arrows either side of it will not change this.

I suspected this might be meaningless with a JPEG but was not sure how you got the 25 figure. I think that you started with a longer duration clip then dragged the handles to shorten it by 25 frames before butting it up to the other clip and then opening the object trimmer. In your earlier example you must have shortened it by 61frames.

This might seem a little odd as to why have this Object content box at all but it is useful in that it is the only way of seeing at a glance whether the clip in the timeline has been previously trimmed and if there is more material to play with if you want to customise a crossfade. I still think it would be useful if this was indicated at the border of objects in the timeline with either a colour bar at the border of the clip or/and a frame count indicating how many frames have been trimmed. I think some of the Pro NLEditors have this.

This was not such an issue where we used to start with say 1 hour tape captures and then cut them in the timeline such that there was always material either side of the (virtual) cut.

I am not sure what you mean with the half frame thing but it must be a glitch because it makes no sense to have half frames for editing purposes.

You are right about the descriptions in those trimmers though - you really have to think about what they mean.

Cheers

Peter

terrypin wrote on 6/30/2012, 5:57 AM

Hi Peter,

Many thanks. That confirms my intention to leave this particular feature of MEP well alone - too complex by half!

Re the frame issue, place two JPGs on the timeline, select Thru Black as the transition type and enter 00:01:00 in Set transition length. Then zoom in on either JPG. Here, the 'end of fade' marker is shown midway in frame 12.

What result would you expect? Or putting it another way, how many frames should be included in each half of this fade-out/fade-in? 12+13 or 13+12 doesn't seem to make sense, and 13+13 is not exactly a second.

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Terry, East Grinstead, UK

Scenestealer wrote on 6/30/2012, 6:54 AM

I think the key here is that the Fade is a brightness change over time and as such is not frame dependent so it is shown correctly as 12.5 frames at 25fps.

If you scrub your example you will see a subtle continuous brightness change from 1 frame marker to the next and the fact that changing the effect/time in the timeline or trimmer, makes it snap to the nearest frame, is just the way MEP is configured to avoid problems with other frame dependent effects. I can not believe this would create a problem in practice but an interesting observation on your part.

I would not want to write the trimmers of completely as they do have some uses as explained earlier. I use their unique ability to temporarily (no permanent files created) render a transition effect for smooth real time preview ( the Floppy disc play button) when the computer gags on it. I just wish their monitor windows were a little larger.

terrypin wrote on 6/30/2012, 8:18 AM

Thanks Peter, that neatly solves the 12.5 mystery!

As for the trimmer, I expect I'd have to work through a simple practical example before the penny will drop on that.

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Terry, East Grinstead, UK