Need ideas on fixing noisy video before encode

[mdhare]

I have some footage from a camcorder that was pretty noisy. Strangely enough, after feeding it in, I discovered only every other frame was noisy. So, I thought I'd try processing only every other frame (29.97 -> ~15fps) before converting back into an SVCD.

Problem is, when I use tmpgenc to convert to SVCD, there are TONS of artifacts during camera motions. If I take original noisy 29.97fps footage and convert, I don't see any of these artifacts during camera motion. I can tone down the noise with some filters but I'd really like to use the 15fps footage because it is relatively clear.

(btw, I've tried interlaced and non-interlaced modes with tmpengc and got similiarly bad results; I'm not sure how decimating every other frame effects this setting).

Any ideas?

Thanks-
-Michael

[Anonymous65]

The problem with the original tape is that one of the record heads had a clog. So, every other field will be bad. If you capture x240, you could be lucky and only get the good frames. Otherwise, you will have to capture both fields, and try to dump the bad half.
Without removing the bad fields, it will really mess up the mpeg compression.

[mdhare]

Skittelsen-

Thanks for the reply. I did my original capture in virtualdub @ 480x480. I'm starting to learn about interlacing, etc, but I'll admit I'm still a little lacking in knowledge; It's one newbie guide I couldn't find here!

Is the (video->frame rate->process every other frame) equivalent to the approach that you've suggested, or is there something inherently different in the method you suggested of dumping the bad fields?

Here's a screenshot of the noise I'm encountering if it helps diagnose the problem any further. Every other frame this clean/noisy pattern. Just to restate, I can create a 15fps AVI with all 'clean' frames, but the resulting mpeg looks horrible.

http://farnsworth.wiscnet.net/~m7h/frame1.jpg
http://farnsworth.wiscnet.net/~m7h/frame2.jpg

I've read in another current thread that it's not a good idea to even try to MPEG with something of this low of framerate (15 fps); maybe that's my largest obstacle.

-Michael

[Anonymous65]

Yes, it looks like you have a worn head for field 2, giving you poor chroma levels. Try to capture the video at 480x240, and see if you get all the bad fields or the good fields. If you get the good ones, then you can make a VCD or SVCD from the 30 good fields. If you get only the bad fields, then you have to find a way to dump the bad half of the 60 fields. In eighter case, you will not end up with 15 frames, you will always keep your 30 frames, but you might have to upconvert your 480x240 to 480x480 if you want to make a SVCD. If you're making a VCD, then you're all set with a capture at 352x240. If you're using Vdub, try playing with the field order so you get only the good fields. As a last resort, you can make it black/white and remove the color.

[mdhare]

Looks like I'll have to keep tinkering around. Tried capturing at 480x240 with and without the fields reversed in vdub, and my captured video still showed the same problems. An issue with my capture card/driver.? I'm just using a Asus 6600; i don't even know the encoder chipset.

In reality encoding the 480x480 bad fields with noise reduction and smoothing is better than the original source, so I'll probably settle for now. Thanks for all your advice, it was helpful.

-Michael

[garbman1]

You might try using deinterlace in TMPGEnc. Try using just odd fields or just even fields. I am not all that sharp on how interlacing and fields work but, when I tried those settings in some of my encoding and it looked like I was only getting half the frames.

[mdhare]

The deinterlacing inside Virtualdub did the trick!!!!

I should have tried this before. I had to switch between duplicating field A and B on various clips but with tmpgenc's mpeg-tools, combine them back into a coherent piece was a snap.

Thanks!

-Michael