Working Chroma noise filter anyone ?

[Demone]

I'm planning to capture various concerts from vhs but I have a big dubt: I dunno if use my pinnacle DC10+ or go out and buy a Canopus ADVC series you know 50-100-1394.
I read very good comments about the the advc series, but dunno respect to my DC+ how they work.
Another thing, capturing from VHS you know, chroma noise...
Investigating, I found this picture on the web (see link) and I cant find any filter for virtualdub that let me recreate this restoration, basically a chroma noise reduction should do, but every cnr filter I found simply doesnt work AT ALL !!! :( any help ?

This is the shot:
http://space.virgilio.it/gnomomagico@tin.it/PensaSuhr/filter.jpg

[scharfis_brain]

You have to denoise the Luma, too.
(DNR, temporalsmoother and a lot more filters)

Additional Spatial denoising will also help much.
(I had the best results with SmartsmootherHiQ, but is is extreme slow)

[Demone]

You dont end up smoothing too much ?
If you look at the image the detail is holding as the original.
Your telling me that if I apply a chroma noise only it will have no effect ?
Can you list ALL filters I could be interested into ?

Thank you :)

[scharfis_brain]

Oh, I can't tell you ALL NR-Filters, but http://shelob.mordor.net/dgraft/ will be a good place to start with.

I am now filtering with AVIsynth, since it gives me much more flexibility and speed than Virtualdub, so I forgot a lot of things :rolleyes:

[Demone]

I'v no problem filtering with avisynth, the fact is that virtualdub let you modify filters on the fly with a preview, so its more direct, btw I just want to remove rainbows...perhaps antiblink for avisynth will do will do it, then I think the key is spatialsmoothers ?

[vmesquita]

Try the FlaXen VHS Filter for VirtualDub.

flaxen.dynip.com/vdf/fxvhs/help.html

[]'s
vmesquita

[Demone]

I got it, I'll experiment then.

[scharfis_brain]

I won't recommend the flaxen VHS FIlter for denoising, because it is a bad denoiser (and slow, too). I've used it only for chromashifting.

In this Thread http://forum.doom9.org/showthread.php?s=&threadid=23884 you'll find an AVS which I've used to filter a NTSC-VHS, but it'll be usable for PAL-VHS too. There is also a screenshot, of which I think, it's a good quality for this >8yrs old Tape.

[^^-+I4004+-^^]

good CNR filter will remove the chroma noise completely (except for mild chroma "crawl" (noise leftovers/scenechange poor detection) that will be left on scene changes,but this is not visible in normal playback speed but only in frame by frame analisys...)

in general,CNR won't touch luma too much (so only problems are mentioned chroma noise leftovers in scene changes...as i said not visible in normaèl playback)

this filter is good if you have VHS you want to denoise but want to preserve as many luma detail as possible (but sure,you'll have to go for higher bitrate as you didn't really denoise luma at all!)

i have wonderfull experience with VDub's CNR (i think version is 2.something or so...don't hold to it,but check graft's web..,as i rarely process in VDub these days..)
and not so good results with avs' port of same filter..........

btw. the image you linked was temporally smoothed,something like my sample here:
http://i4004.0catch.com/lo-res%20filtering.htm
all the settings used are mentioned too.........

[vmesquita]

I'll try this avs, if it gives me a better result than Flaxen (or the same result, but faster, since Flaxen is very slow), I might change... I'll post the results. What about CNR, I4004? What settings do you recommend, and what denoise would you use with it?

[]'s
vmesquita

[^^-+I4004+-^^]

Originally posted by vmesquita
I'll try this avs, if it gives me a better result than Flaxen (or the same result, but faster, since Flaxen is very slow), I might change... I'll post the results. What about CNR, I4004? What settings do you recommend, and what denoise would you use with it?

[]'s
vmesquita

flaxen's vhs is not just cnr (in fact i dunno how much is it cnr at all) but more general smoother.........but as you said,it's slow and the parameters are not explained/defined that well........

in vdub i used cnr with mild setting (narrow looking graphs etc.)
perhaps i just didn't played that much with avs version,as it should be the same thing ad vd version (and i think it has wider span of paramteres etc.)

bare in mind that chroma noise is only a portion of overall noise in video,but never the less,chroma takes bitrate too.especially noisy chroma....

when i used cnr i didn't used any denoise after (or before it),because i wanted to preserve sharpness (at the cost of luma noise /higher bitrate etc.)........

when i use hard core smoothing (temp/spatial) it needs no cnr anyhow,as temp smoother will "eat" all most of the chroma noise too...also,i believe in vdub i got some erroneus interactiones between cnr and temp smoother/the image got blurred rapidly after adding cnr in conjuction with t.s.

so ,don't expect compressability miracles but the chroam noise can be completely cancelled,that much is true............

lately i've been using "peachsmoother" and grape one too,as they serve me well for hires captures and are very fast...they are built o leave some noise in...to preserve the sharpness...very nice!

in any case,some tradeoff's have to be done.....for sure,cnr is the least you can do for vhs,as it needs it always!

[Demone]

Thank you for your help and explanations :p
One thing that I dunno is the f....ing resolution of PAL vhs...
I mean I'v read all topics about the vhs and pal resolution, but finally, for a perfect high fidelty capture, whats the optimal resolution ? 768 ???
I could put up a piece of the capture if someone want to see it.

[scharfis_brain]

have a look at this Thread:
http://forum.doom9.org/showthread.php?s=&threadid=52165

there is an example-capture for download. It is done very well.

I've added two AVIsynthscripts for denoising it, maybe you can adapt it for your captures.

both scripts will work with 768, 720 or 704 Pixels horizontal and 576px vertical input resulution. The Result is (nearly) the same.

[vmesquita]

I tried the first script scharfis_brain suggested, and that gave me a picture smoothed *a lot*, even for VCD encoding (looked like some low bitrate cam releases available on the internet)
I am using this filters to put some VHS in VCD (not because I love this format, but because its supported in a lot of players and I am doing this for other people, DVD burners and media are still very expensive here in Brazil. When encoding stuff for me, I use DIVX or SVCD, depending on how much motion the source has).

Today I just found out interesting stuff: using no smoothers (like the FlaXen filter for chroma, the only one I was using before), and discarding one line (rather than tomsmocomp), I get a much better looking video, with very few visible macroblocks (and less "dancing" blocks, also). There is also slightly more mosquito noise, but they are much less perceptive than the blocks. Also interesting to notice that the tape I used for the test, althrought was in good shape, the tape was about 11 years old... The clip was a children birthday party, with lots of camera movements.
But I think I can improve a little more with some filtering, so I'll give peachsmoother and grapesmooth a try.
It seems the TMPGEnc encoder (with Highest motion effort, macroblock softing and other settings, but *no* noise reduction) does a better job than Flaxen. More tests are needed, anyway. i think standard VCD is not very common in this board, but any comments would be apreciated.

[^^-+I4004+-^^]

if i resized from 7xxx576 to vcd res. i wouldn't use any filtering,as image is already blurred enough by resizing....
but if i captured at lores,sure i'll filter it....(as it'll stay lores,so only soem denoising can cure it...)
anyhow,try peaches and grapes,as they try to preserve sharp edges etc.
also,i won't filter if i need to see the skin as it is...(color and detail) for example in porn....

btw.what does this
>"and discarding one line"
mean?
non standard resolutions for vcd?
adding black border for one line only?
didin't quite catch that,explain a bit better,if you would......

[vmesquita]

I mean deinterlace by discarding one field, sorry. I first tried to deinterlace doing tomsmocomp and resize, but it seems to increase the complexity of the movie, increasing the compression artifacts. I think (and seems that most people I asked also do) that a image with less detail (and less smooth) with less artifacts is better than one with more detail and more smooth, but also with much more compression artifacts (not to mention deinterlace artifacts).
But if I capture at, say 720x480 (NTSC), and resize to 352x240, that might also denoise the picture? Of course, I'll have some ghosting, but using smart deinterlace with bicubic interpolation enabled would (maybe) solve this... I'll do some tests.

[^^-+I4004+-^^]

>But if I capture at, say 720x480 (NTSC), and resize to 352x240, that might also denoise the picture?

heh,are you kidding?consider resizer as one extra blur filter and you're there.......
just deinterlace,resize and if there's much chroma noise do cnr....
that way image will suffer the least

also,resizing as denoising has no ghosting in fast motion (off course you must deinterlace first) as all denoisers do...
vcd is cca. 1100kbit/s and even for mpeg1 it's not that bad...
shoudl swallow some noise to (if there's some left after resizing)

if you discard one field,then you migth as well capture at lores...
it'0s the same thing

if you have subtitles in your video,this (one field only) makes them blurred as hell!
i see you're from brazil,do you subtitle foreign stuff there or dub?
(my condolences if you dub..hehe)

cheerio

[vmesquita]

Interesting... So I might get better results capping at 640x480, deinterlacing e resizing to 352x240... I'll do some tests...
I am doing mostly home videos, so no subs yet... But here in Brazil "free" TV stations dub things (argh!), and generally cable channels use subs.

[]'s
vmesquita

[Demone]

^^-+I4004+-^^
I capture to do DVD (so without interlace), is it right to capture at 720 ?
Could be better @768 and then apply a resize to 720 to smooth chroma noise ?

[scharfis_brain]

a resize from 768 to 720 will not reduce the chromanoise, because chroma is saved with lower bandwitdh than luma.

If you are using VHS, you have approx. 50 - 70 lines of horizontal chroma information and 200 - 240 lines of horizontal luma information.
The noise will have the same bandwidth.

[vmesquita]

Ok, now I am capping at 640x480, and doing the following:

SmoothDeinterlace(tff=false, doublerate=false)

GrapeSmoother(45) # to kill the color oscilation

Crop(12,12,616,456).AddBorders(12,12,12,12).BicubicResize(352,240,0,0.75)

First I tried Tomsmocomp, but it smoothed the picture even more. I got less artifacts, of course, but a much blured movie. I was wondering, since standard VCD has a fixed bitrate (and I have to stick with it), would be a filter do blur the image if it gets to complex, and sharp (or do nothing) if the frame is below a certain level of complexity.

[]'s
Vmesquita

[^^-+I4004+-^^]

>Could be better @768 and then apply a resize to 720 to smooth chroma noise ?

this will blur image a bit (same as any resizing) and therefore remove some noise (detail too obviously),but it's small ratio,so results will be hard to spot.....

but 768 makes for better source anyhow....(wether you'll resize it to 720 or less....)

>would be a filter do blur the image if it gets to complex, and sharp (or do nothing) if the frame is below a certain level of complexity.

the combined temp/spatial smoother "mam" claims to do this,but to be honest i didn't saw him doing it!(i tried it abit..itt acts like an combination of temp and spatial smoother..nothing more (ie. it's nto real motion detection and then blurring the fast moving parts....it's just 2 filters put to one...no use...)

anyhow,u can use ffdshow to temper with vcd video on playback (if you play it back on PC obviously...) tick "raw video" and adjust the image....(only this way it's really visible how poor mpeg1 is,and how much more mpeg4 image can be tweaked to satisfy teh eye....but you shoudl try it anyhow...vcd usually is too blurred..)

also,i believe cnr version for avs2,5 has motion detection which will shut it off for faster scenes..(i needed this for some moto racing,but there's no avs 2.0x version...so...not good....)

[vmesquita]

I'll make some tests with this mam filter them... I am targetting standalone for VCD playback, so ffdshow won't help... But I use it for my DIVX stuff and look great!
I couldn't find cnr for Avisynth 2.0, where can I get it?

[]'s
Vmesquita