VirtualDub Filtering

[pburdett]

Why does filtering with VDub triple my file size?

I have done some editing to a captured avi clip using VideoFactory. The edited clip was again saved as an avi file. I wanted to do some noise reduction so I ran the file through VirtualDub with the 2-d and the temporal filters. A 15 Gig file turned into a 45 Gig file. What's up?

Also, TMPGEnc has some of its own noise reduction filters. How do these compare with the VDub ones? Should I bother with any filtering before going into VDub? My premise has been that eliminating some noise would improve quality a bit and reduce the bitrate requirement a bit. Does this make sense?

Yet another question. When I play back the filtered file it plays back in slow motion and the audio is distorted. My guess is that I may be exceeding the bitrate limits on my softwared player. Given that the file has tripled, the bitrate must have tripled as well. Am I right? What can I do about this.

[KingJohn]

When you load a compressed AVI into Vdub and add a filter, if you don't change the default compression you will save out a uncompressed file.

Vdub
Video > full processing mode
Video > compression > codec > bitrate (match source)
Video > filter > add > filter

Audio > direct stream copy
SAVE AVI

[pburdett]

Thanks KJ. I didn't realize my VideoFactory was using compression but it must be. I tried the filters on some raw capture data and the files did indeed shrink like I expected them to.

Let me test your (or others) VDub wisdom further -- I am trying to run a temporal cleaner filter on my raw capture AVIs. Two questions: 1) Should I run a temporal cleaner before or after a 2-d cleaner? 2) How do I use a temporal filter that does not have a zero time lag? Do I have to split off the audio and re-multiplex? If I do, will the new clip sychronize properly?

[KingJohn]

Temporal filter is an adaptive noise reducer working along the time axis, its best when working when the scene is not moving much, its best used with with a spatial noise reducers. There is also a lag between input and output frames, so preview is also lagged. No use at all if used when frameserving.

2D what ?, I guess you need to have it before ? I don't use filters, sorry cannot help further

[pburdett]

The "2-d cleaner" I was talking about is the same "spatial noise reducer" you are talking about, I think. I was wondering what is the better order to apply these, since they are done sequentially.

Essentially, the question is, when analyzing a pixel for noise is it better to:

1. compare it to the pixel beside it on the same frame, or
2. compare it to the identical pixel on the next frame.

And you were prescient regarding my time lag question. I was trying to use frameserving with the temporal filter turned on. As you noted, it just doesn't work.

[KingJohn]

2. compare it to the identical pixel on the next frame

[chaseru]

Temporal filter . . . No use at all if used when frameserving.

I agree that VirtualDub's built in Temporal Filter doesn't work with frameserving, however I've been successful in using Jim Casaburi's "Temporal Cleaner" with frameserving.

VirtualDub doesn't give the "lag" warning when frameserving is initiated with Casaburi's temporal cleaner like it does with its built in temporal filter. There is a substantial reduction in video noise in the resulting MPEG2 file using the Casaburi's temporal cleaner - so it must be working. However, it does take about 3 times longer using this filter.

Transferring my kids VHS cartoons to DVD using Casaburi's temporal cleaner along with an optimized version of his 2d Cleaner, video noise is effectively eliminated - they look almost as good as an original DVD. For live action VHS transfers I use the same filters but with the blur/averaging settings down a bit so I don't loose detail.

[vhelp]

Evening all.
.
.
based on some experience w/ Temporal (any) filtering, some will not
work 100% quality'wise or the way you want.

You sometimes, have to do the un-thinkable..
--> source -> vdub -> your Temporal filtering -> to new AVI, then
--> new AVI --> vdub OR tmpg ..and encode to whatever format.

I can't say with 100% certainty, but I do remember seeing an actual
difference -- well, at least in final size. You be the judge. Just do two
small sample test runs, and see for yourself, using the Temporal filter
that is causing you the quality problem. If there is any difference is size,
then you know I was getting at, above

Don't know much for your Source quality, since you didn't say, but it
couldn't hurt ty have a looksees at these (below)

However, you can also try the following:
Trumans AVISynth scripts:
--> How to frameserve (dvd2avi / VirtualDub / Avisynth / VFAPI)

SansGrip's:
--> SansGrip's Filters via AVISynth scripts, as he has many other
filters you could try.

And check out:
--> AVISynth for other tid-bits, as they could prove useful too.

Hope that helps some.
-vhelp