Render time with Track FX 'off' slow

gbohn wrote on 2/7/2002, 8:38 AM
Hi;

I've been playing around with Vegas Video 3 some NTSC DV clips at 720x480 resolution. I think I see an unexpected performance problems with Video Track FX.
Basically, even when the effects are set to a value where they should have no effect on the video, it still seems to have a massive effect on render times.

Please let me know if I should be doing this a different way, or if this is really a problem with VV3 performance.

I have a two hour DV clip and there are sections that I wanted to adjust brightness on, as well as reduce noise with Gauusian Blur/Sharpen. Since this footage was captured from a Hi8 camcorder, I also wanted to use a very small border filter to remove the 'ragged' effect at the bottom of the picture where the bottom most few two or three lines are garbage.

I set up four plug-ins using the Video/Track FX panel. I set up keyframes where I use the individual filters settings to effect whether correction is done or not. For example, the first 'noisy' section is about 15 minutes into the DV clip. So, the first keyframes for Brightness/Blur/Sharpen are set to the 'Neutral' defaults. Then at about 15 minutes in I added new keyframes where I 'turned on' the effects by setting values for correction. At the end of the noisy sections I turned the setting back to 'neutral'.

For 'Neutral', I set Gaussian blur to 0.000 in both H and V directions, set sharpen amount to 0.000, etc.

As a test, I picked 20 seconds from the start of the DV clip where no effects should be active (I unchecked 'border' from the Filter plug-in list to eliminate its effects). I then did a render as 'Video for Windows .AVI'/DV NTSC. This takes about 3 minutes to render on my system. If I go back to Track FX and uncheck Brightness/sharpen/ and Gaussian blur the same render takes 6 seconds.

I double checked and the Brightness/sharpen/Gaussian blur settings should all result in no net correction. Even moving the first keyframes in Track FX to a point after the end of the test section still shows these large performance hits. (With the first keyframe after the end of the test clip, I would have thought the program would know no effects are possible at that point in time.)

I would have expected sections with no correction (due to neutral settings) to render at full speed. Am I just doing this the wrong way?

My concern is that If I add a few seconds or minutes of correction to my 2 hour clip, I suddenly may take a hit for the entire length. In this case, I would seem to turn a 35 minute render into an 18 hour ordeal.

Thanks;

-Greg Bohn

Comments

SonyIMC wrote on 2/7/2002, 10:03 AM
When you place and effect on a track even if its on neutral settings or 'no-op' as we call it around here you will force a re-render of the entire clip. My advice is to separate the areas that you want to apply an effect to and cut them from the clip pressing 'S' at the boundary location of the areas. Then apply event fx to the resulting clips. This will save a lot of time as the entire clip will not need to be re-compressed anly those that you changed.

Good Luck
gbohn wrote on 2/7/2002, 10:39 AM
Might I suggest this as an enhancement request? It would seem to me that forcing the entire track to be 'rerendered' when any effect is applied at any point limits the usefulness of the keyframeing feature.

In my case, it seems like extra editing work to have to cut out the sections when they could have just been keyframed.

Thanks;

-Greg Bohn
HPV wrote on 2/7/2002, 11:10 AM
In my case, it seems like extra editing work to have to cut out the sections when they could have just been keyframed.
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Hitting the S key on your keyboard a few times is not much to ask to get your render times faster. Split the clip before and after where you want a filter. Your not moving anything around, just splitting. Apply the filters at clip level, not track level.
Whenever you need a track level fx or track motion, only use that track for the clips that need the adjustment. Put other clips on new tracks.

Craig H.
gbohn wrote on 2/8/2002, 10:55 AM
It wasn't the hitting 'S' part that I was worried about. It was dragging the clip to numerous new tracks that seemed painfull.

I didn't realize there was a way to keep the split clips in the same track and use a different effect setting for the individual clips(I'm new to VV so please bear with me). It looks like the 'clip level' effects you mention are listed as 'Event FX'.

I'll have to give them a try. Even so, being able to have the program ignore areas of track FX where the effect is basically 'off' would still seem to me to be a useful enhancement request...

That's assuming that implementing such a speedup wouldn't be hard to implement in the code.

Thanks;

-Greg Bohn