Generational Quality Loss?

[peter orland]

When you apply a filter or effect in AE then render, I'm assuming that the render section of the file becomes a second generation copy of the original with the effect now applied.

If you then continued to apply affects or filters one at a time, rendering after each application, does that mean that every re-render becomes a further generation away from the original, 1-2-3-4-5 etc..?

If you applied all the filters and effects at the same time, then rendered, does that mean that even though you may have applied say, 5 filters/effects, that because it is rendered as a unit that it is only one generation from the original file, or is it the same as if you applied them separately (as above)?

Hope that makes sense.

Thanks.

 

[Huy Vu]

I think it has more to do with the compression codec that you use to render out each time than how many effects/filter you apply on it. If you render it out as uncompressed everytime then theoretically there should be no loss in quality no matter how many generations it is. But if you render the 1st generation as mpeg for example then there would be a degrade in quality if you render the mpeg file out a second or 3rd time, even if you applied no effects. That's why it's best to only render things out once.

 

[Matt Grunau]

When you apply a filter or effect in AE then render, I'm assuming that the render section of the file becomes a second generation copy of the original with the effect now applied.

If you then continued to apply affects or filters one at a time, rendering after each application, does that mean that every re-render becomes a further generation away from the original, 1-2-3-4-5 etc..?

If you applied all the filters and effects at the same time, then rendered, does that mean that even though you may have applied say, 5 filters/effects, that because it is rendered as a unit that it is only one generation from the original file, or is it the same as if you applied them separately (as above)?

Hope that makes sense.

Thanks.

It makes sense, but in a word, no.

WHen you work on something in After Effects, you are working with uncompressed data within the program. Even if you opened a 5 meg DivX encoded file that was 5 mins long, AE would treat it the same as if it was a 5 min long file unompressed. AE is not a destructvie editor, which is why you can apply, remove, change the oder of effects and keyframe their values, and so on. The only time compression happens is when you export/render, and that is based on what you decide to use as your codec. (unless you consider when you RAM preview something at half rez for speed, and I don't think that's a compression)

That's why unlinke Premiere, FCP, and even Vegas to a degree, you REALLY need tons of ram to view any realtime video of any length.

AE does not use the video's native codec to play it (but that codec IS required to decode it), which is why you have probably noticed when you press play in AE, it does not play realtime. AE also deinterlaces interlaced footage as is plays, slowing it further. The reason for all this is to get it to an umcompressed/progrssive format before you apply effects. Makes things simpler that way.

Lastly the order you apply your effects will make a difference as well. For instance, you mght not want to apply Curves after a Blur, but might want to apply them after a noise cleanup.



[Cpt. Jack Sparrow voice]

Savy?

[/Cpt. Jack Sparow voice]

 

[oneinfiniteloop]

In addition to the great info Rapier provided, render order/precomping/prerendering is as much art and science as anything else in AE. To truly take advantage of AE, you need to spend some time understanding when it's best to precomp/pre ren and how effects, etc render.

 

[Matt Grunau]

render order/precomping/prerendering is as much art and science as anything else in AE. To truly take advantage of AE, you need to spend some time understanding when it's best to precomp/pre ren and how effects, etc render.

That's something I've never really paid the heed it warrents, though it shames me somewhat to admit it. Most of my precom work is just to save from the hassel of multiple layers clogging things up, and I don't think I've ever done a prerender, though I can think of about a billioin reason why I should.

In addition to the Color Finesse tutorial we have been waiting for from you oneinf (nudge nudge), mayhaps a breakdown and more info of what you are mentioning above would be a nice thing.



*cough-Color Finesse Tutorial-cough*



Sorry, had something in my throat.

 

[peter orland]

Thanks for the input guys, much appreciated.

I'd also like to see something on the Colour Finesse tutorial.

Thanks.

 

[oneinfiniteloop]

That's something I've never really paid the heed it warrents, though it shames me somewhat to admit it. Most of my precom work is just to save from the hassel of multiple layers clogging things up, and I don't think I've ever done a prerender, though I can think of about a billioin reason why I should.

In addition to the Color Finesse tutorial we have been waiting for from you oneinf (nudge nudge), mayhaps a breakdown and more info of what you are mentioning above would be a nice thing.



*cough-Color Finesse Tutorial-cough*



Sorry, had something in my throat.

I'm with you Rapier, I know I should be more wary of these things, but I usually precomp for the same reasons, but lately, as I've tried more complex things, I find the need to precomp to get certain effects.

About Color Finesse, I've been actually looking for a screen capture program so that I could do some video tutorials...also been busy, but we all know how that goes, but, can anyone suggest a good, free screen movie cap program. I might just buy one, but free doesn't hurt!

 

[graymachine]

What platform are you on? I use Snapz Pro on the Mac.. but I hear the Windows folks raving about Camtasia Studio.

Snapz was $60, I think. You get a month of nagware for free when you DL it.


Regarding the precomping, people often overlook the extremely useful Adjustment Layer when resorting to precomping. It's not a magic bullet, but it often eliminates the need for precomps.

But, sometimes, it's just what you gotta do.

 

[oneinfiniteloop]

I'm on Mac and I think I checked out Snapz, but I'll have to take another look, thanks!

 

[Steve_Arm]

Precompositing is very important for certain effects. For instance this simple example:

You have a layer with alpha in front of other layers. You apply to this layer Trapcode's Shine.Now the rays won't come out of the layers "space". So you will have to apply the effect to an adjustment layer to work like you want. But hey, the adj layer will
be grab everything that's underneath it. So you precompose the first layer which becomes full comp size and Shine works as wanted.

Some words about AE. AE works with pixel data, it reads pixel and it displays them. For each frame in the comp AE runs a loop starting from the first layer reading it pixels then if the layer had effects it reads the parameters of the effect each one calculates the results from the existing image buffer and proceeds to the other effect and so on up to the last layer in the comp, then moves to the next frame. Now if you grab the concept you will understand how fast are computers these days. As for each frame to display one layer only it runs a 720x576 = 414720 iterations. Concluding if you had a layer and pressed stop to play the timeline it would play real-time only if the computer would be able to render a loop ( frame) under 1/25 of a second... in PAL

 

[Matt Grunau]

You have a layer with alpha in front of other layers. You apply to this layer Trapcode's Shine.Now the rays won't come out of the layers "space". So you will have to apply the effect to an adjustment layer to work like you want. But hey, the adj layer will
be grab everything that's underneath it. So you precompose the first layer which becomes full comp size and Shine works as wanted.

Not to mention displacement maps and compound blurs.

 

[graymachine]

I would never say that precomping isn't necessary.. just that Adj Layers are often overlooked.

In fact, I am working on a piece right now with a nested comp that has an edited sequence of clips, but I nested them into a comp so I can apply one mask to the comp rather than each clip. It's a handy thing.