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Old 17th September 2010, 14:47   #1  |  Link
twipley
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Snow-like, white-lines noise (results in huge Xvid file)

Hello, hello.

I have this short SLP clip I've just captured. Other (SP) clip captured/played well on the VHS deck, however, probably partially because the tape is over 20 years old, SLP-section recordings playback with lots of horizontal white lines inter-spaced throughout the whole screen. In other words: no image three-fourths of the time, but audio is still there and well enjoyable.

Sweet family memories. However, when encoding that 10-minutes capture to (Q3) Xvid, the file size gets quite huge, more so compared to that of my other (SP) captures: we here are talking of multiple GB.

The question is, would there be an easy way to diminish the file size of the Xvid encoding? I still have the source file (7.8 GB; Huffyuv).

I have tried both of those noise-reduction plugins (for use with virtualdub), to no significant effect on file-size reduction:
http://www.risingresearch.com/en/denoise/
http://compression.ru/video/denoising/index_en.html

There must be some Xvid setting I'm not aware of, which would be useful to me. I am assuming the static snow to be the source of the weight of the video stream, though it is also to be noted that its frame rate is unconventional, say 30.xx, which was the result of having selected audio as the master stream in my capturing program.

The VHS deck seems not to have been the problem here, as the only recordings which display snow, white-lines static are the SLP ones. It thus seems to indicate that the video heads are in no special need to be cleared, here. SP playback is as clean as it should be. SLP playback on those old tapes have snow-snow issues.

EDIT: a Q8 encoding has been tried, which diminished the 10-minutes-long video stream size to an acceptable 600 MB or so, but the problem here is that anything lower than Q3 (e.g., Q4) in terms of encoding quality puts the parts of the video where static is less present at a significant decrease in quality. I would want something like Q99 to automatically be applied to the snowy-screen areas, while Q3 to be at any pat where the original-recording picture is actually visible.

Last edited by twipley; 17th September 2010 at 14:52.
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Old 17th September 2010, 16:06   #2  |  Link
Ghitulescu
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You have to recapture again the whole thing.
Find a better player, use a TBC, and set the Video as the synch--master.

Of course, there are software solutions to use the video and the audio, but no software can correct what a broken source/player does.
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Old 17th September 2010, 17:06   #3  |  Link
twipley
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I think the problem is the unusually large number of keyframes. Wouldn't there be any way for it to be reduced, so that the final-result file size be reduced accordingly? Usually it's like one keyframe every 300 frames, but here it's like (for the most part) many keyframes every 30 frames. It's like 20 times more, perhaps the reason for taking 10 times as much space as other streams of its length.
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Old 17th September 2010, 17:48   #4  |  Link
pandy
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Quote:
Originally Posted by twipley View Post
Hello, hello.

I have this short SLP clip I've just captured. Other (SP) clip captured/played well on the VHS deck, however, probably partially because the tape is over 20 years old, SLP-section recordings playback with lots of horizontal white lines inter-spaced throughout the whole screen. In other words: no image three-fourths of the time, but audio is still there and well enjoyable.
where is the picture...
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Old 17th September 2010, 19:32   #5  |  Link
twipley
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the picture is there one-fourth of the time, when there is no snow covering the whole screen like the other third-fourths of the time, that is.
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Old 17th September 2010, 19:43   #6  |  Link
poisondeathray
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by "picture" he probably meant screenshot or sample video - to get an indication of how bad it is

you probably have to recapture or use better equipment as suggested above , but there are some avisynth filters that can improve dropouts , comets.

but your edited post suggests it comes and goes , I'm not sure how you would get any program to increase quantizer automatically for those sections, short of manually encoding in sections or using zones in xvid

Last edited by poisondeathray; 17th September 2010 at 19:49.
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Old 17th September 2010, 21:07   #7  |  Link
twipley
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Alright. I am uploading an excerpt as I am writing. It will be attached (Huffyuv) at the end of this post.

Really. This VHS deck is worth like USD 300. I also tried on another one. Results the same. I am happy with the result, however. Sound is great.

I think that maybe it is because the video stream is too complex, that there are so many keyframes, and that the encoded video, as a end result, is so heavy. Maybe I will try to manually increase the Q for the snowy sections if there is nothing else to do. I don't even know if that 10-minutes, though almost 3-GB-big, file is playable on my standalone DVD player. I would just want to tell Xvid that I am not caring about those horizontal lines and wouldn't mind them not being encoding at high quality at all. :S

EDIT: http://www.megaupload.com/?d=M9LUVL0A

Last edited by twipley; 18th September 2010 at 01:22.
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Old 18th September 2010, 03:11   #8  |  Link
twipley
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I've found this thing: http://avisynth.org.ru/descratch/descratch.html

But have never yet fiddled with Avisynth. Seems max complicated. Spent hours and accomplished practically nothing valuable. :S
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Old 19th September 2010, 02:57   #9  |  Link
zilog jones
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No amount of filtering will save that! It's destroyed - either the tape is damaged or your VCR is not capable of playing it for whatever reasons. You say SP playback is fine, but doesn't SLP/EP use different heads? Maybe only they are worn/damaged/dirty somehow. If it's anything like LP it can be difficult playing it back reliably on anything other than what recorded it in the first place. I'd seriously suggest trying some different VCRs if possible, even some cheap old junk may play it better. 20 years shouldn't do this to a tape, I've gone through many from the '80s that play fine.

If the tape is actually damaged (have you checked it for mould? Is the tape creased?), I would just duplicate the good frames and get rid of the junk, but you would have to go through the whole thing manually to select the good frames (unless anyone knows a better way?).
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Old 20th September 2010, 15:14   #10  |  Link
pandy
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zilog jones is right - check the tape - seems that this main suspect - if tape is ok then use different VCR
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Old 27th September 2010, 13:47   #11  |  Link
2Bdecided
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Quote:
Originally Posted by twipley View Post
Hello, hello.

I have this short SLP clip I've just captured. Other (SP) clip captured/played well on the VHS deck, however, probably partially because the tape is over 20 years old, SLP-section recordings playback with lots of horizontal white lines inter-spaced throughout the whole screen. In other words: no image three-fourths of the time, but audio is still there and well enjoyable.
It really looks like your playback machine can't play SLP recordings!

Find one that can. (there's nothing you can do with this capture).

With the right machine, this should play back well enough - unless it wasn't recorded properly in the first place. In that case, the best chance to play it would be finding the original machine, but I guess that's long gone?

Videos can and often do last for 20 years or more without noticeable problems.

Cheers,
David.
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Old 18th October 2010, 07:02   #12  |  Link
jmac698
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For the record, I don't agree with this at all. I've successfully managed to recover such a tape through both software and a proprietary technique. This type of noise often occurs on 20+ year old tapes. I tried the tape in a professional VCR with TBC and it looks the same. It is not the VCR.
I found 3 or 4 filters that work in combination. Descratch as mentioned is one of them. There's also only a few very heavy general denoisers.
The best results come from combining all filters, the result has no more white lines but looks strangely chunky (due to heavy interpolation in damaged areas).
Using a technique I developed myself, I can completely recover the tape with no missing pixels or noise whatsoever. I provide this service.
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Old 24th October 2010, 22:31   #13  |  Link
davexnet
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Why don't you "repair" a few seconds of this damaged video so we can evaluate your "Service" ?
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Old 2nd November 2010, 14:12   #14  |  Link
2Bdecided
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Nah, we'll have to wait until April 1st for that!

Cheers,
David.
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