How to filter VHS cassette artifacts

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How to filter VHS cassette artifacts

Ulf Zibis
Hi,

I have a VOB-file, originally recorded from a VHS-Kassette.

On the upper edge I see a black line from left to the middle.

Approximately 5 lines from bottom I see 2..3 other horizontally shifted
flickering lines.

Filter kerndeint removes the upper one, but not the lowers. But it does
not remove comb-like artifacts from vertical edges which bwdif perfectly
does.

Do one have an idea for a filter which is restricted to only alter those
small lined areas?

Mach thanks,

Ulf

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Von meinem Seibert gesendet

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Re: How to filter VHS cassette artifacts

Carl Eugen Hoyos-2
2018-12-07 20:33 GMT+01:00, Ulf Zibis <[hidden email]>:

> Hi,
>
> I have a VOB-file, originally recorded from a VHS-Kassette.
>
> On the upper edge I see a black line from left to the middle.
>
> Approximately 5 lines from bottom I see 2..3 other horizontally shifted
> flickering lines.
>
> Filter kerndeint removes the upper one, but not the lowers. But it does
> not remove comb-like artifacts from vertical edges which bwdif perfectly
> does.
>
> Do one have an idea for a filter which is restricted to only alter those
> small lined areas?

Shouldn't you just crop them?

Carl Eugen
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Re: How to filter VHS cassette artifacts

Bouke / VideoToolShed

> On 08 Dec 2018, at 11:34, Carl Eugen Hoyos <[hidden email]> wrote:
>
> 2018-12-07 20:33 GMT+01:00, Ulf Zibis <[hidden email] <mailto:[hidden email]>>:
>> Hi,
>>
>> I have a VOB-file, originally recorded from a VHS-Kassette.
>>
>> On the upper edge I see a black line from left to the middle.
>>
>> Approximately 5 lines from bottom I see 2..3 other horizontally shifted
>> flickering lines.
>>
>> Filter kerndeint removes the upper one, but not the lowers. But it does
>> not remove comb-like artifacts from vertical edges which bwdif perfectly
>> does.
>>
>> Do one have an idea for a filter which is restricted to only alter those
>> small lined areas?
>
> Shouldn't you just crop them?

He should as it is intended for computer display or blowing up to HD, as SD is an overscanned format, so about 10% (to tast it seems) should be cropped off.
(Hence you see so many mics dipping in the image, these are NOT mistakes, but good practice to get the mic as close as the proper framing allows.)

Bouke (who is feeling quite old now.)

> Carl Eugen
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> [hidden email] <mailto:[hidden email]> with subject "unsubscribe".

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Re: How to filter VHS cassette artifacts

Ulf Zibis
In reply to this post by Carl Eugen Hoyos-2
Hi again,

Am 08.12.18 um 11:34 schrieb Carl Eugen Hoyos:
> Shouldn't you just crop them?

I don't want to crop them.

In the attached sample you can see the partly broken 1st line (missing
content at always same position) and 2 broken lines (irregularly
horizontally shifted), 5..8 lines from bottom.

How would it be possible, to consolidate them by copy/average from
adjacent lines?

With the extracted sample you can also see a bug in ffmpeg. The videos
SAR is 12:11, so the JPEGs x/y dpi should be 11/12 instead 12/11.

- Ulf

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How to filter VHS cassette artifacts + attachment

Ulf Zibis
In reply to this post by Carl Eugen Hoyos-2
Hi again,

Am 08.12.18 um 11:34 schrieb Carl Eugen Hoyos:
> Shouldn't you just crop them?

I don't want to crop them.

In the attached sample you can see the partly broken 1st line (missing
content at always same position) and 2 broken lines (irregularly
horizontally shifted), 5..8 lines from bottom.

How would it be possible, to consolidate them by copy/average from
adjacent lines?

With the extracted sample you can also see a bug in ffmpeg. The videos
SAR is 12:11, so the JPEGs x/y dpi should be 11/12 instead 12/11.

- Ulf



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CYD_atadenoise_4-45_04_marked.jpg (87K) Download Attachment
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Re: How to filter VHS cassette artifacts + attachment

Paul B Mahol
On 12/8/18, Ulf Zibis <[hidden email]> wrote:

> Hi again,
>
> Am 08.12.18 um 11:34 schrieb Carl Eugen Hoyos:
>> Shouldn't you just crop them?
>
> I don't want to crop them.
>
> In the attached sample you can see the partly broken 1st line (missing
> content at always same position) and 2 broken lines (irregularly
> horizontally shifted), 5..8 lines from bottom.
>
> How would it be possible, to consolidate them by copy/average from
> adjacent lines?
>
> With the extracted sample you can also see a bug in ffmpeg. The videos
> SAR is 12:11, so the JPEGs x/y dpi should be 11/12 instead 12/11.
>
> - Ulf
>
>
>

You can use fillborders filter, but you can not guess correct missing pixels.
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Re: How to filter VHS cassette artifacts + attachment

Ulf Zibis
Hi,

Am 08.12.18 um 21:54 schrieb Paul B Mahol:
> You can use fillborders filter,

Thanks for your hint, but I also don't want to fill the border with
black or what ever.

> but you can not guess correct missing pixels.

It doesn't matter, if the pixels are not 100 % correct.

-Ulf

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Re: How to filter VHS cassette artifacts + attachment

Paul B Mahol
On 12/8/18, Ulf Zibis <[hidden email]> wrote:

> Hi,
>
> Am 08.12.18 um 21:54 schrieb Paul B Mahol:
>> You can use fillborders filter,
>
> Thanks for your hint, but I also don't want to fill the border with
> black or what ever.
>
>> but you can not guess correct missing pixels.
>
> It doesn't matter, if the pixels are not 100 % correct.

Than you need to crop relevant part you want to do special filtering,
and than combine it back with rest of video.
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Re: How to filter VHS cassette artifacts + attachment

Ulf Zibis
Hi,

Am 08.12.18 um 22:59 schrieb Paul B Mahol:
> Than you need to crop relevant part you want to do special filtering,
> and than combine it back with rest of video.

Exactly ... and if I would know a ffmpeg command line for this I would
not ask for in this list.
Thanks for getting what I want.

Is there anybody who can give me some hints?

-Ulf

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Re: How to filter VHS cassette artifacts

Lou Logan
In reply to this post by Ulf Zibis
On Fri, Dec 7, 2018, at 10:33 AM, Ulf Zibis wrote:
> Hi,
>
> I have a VOB-file, originally recorded from a VHS-Kassette.
>
> On the upper edge I see a black line from left to the middle.
>
> Approximately 5 lines from bottom I see 2..3 other horizontally shifted
> flickering lines.

The band of garbage on the bottom looks like head switching noise.

https://bavc.github.io/avaa/artifacts/head_switching_noise.html
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Re: How to filter VHS cassette artifacts

Jason Coleman
I agree with Lou, it looks like switching noise. I've historically always cropped it out of every VHS capture I ever did. I suspect you might think there's something salvagable there, and maybe there would be in the original, if you had special VCRs with the original tape, and re-did the capture. But at this point, it's already part of your video, and probably too garbled to effectively cleaned. I think most VCRs filtered it out on playback, so you really probably do have all of the usable image you probably ever had, and should just crop it.

I'd be curious if I'm way wrong here, but I'm guessing the reason no one has given you a simple way to 'fix' it besides cropping, is that at this point it's a non-trivial thing to fix.  There's no simple set some switches and it'll clean it up for you. Digital captures often showed you more of the picture then you would see on playback on VCRs of the era. It was always there, they just cropped it out because they knew it was there, anmd people would assume something was wrong if they saw it. You really aren't losing anything by cropping, you probably only ever saw the clean part of the signal in what you have now..


-----Original Message-----
From: ffmpeg-user <[hidden email]> On Behalf Of Lou Logan
Sent: Sunday, December 9, 2018 4:26 PM
To: [hidden email]
Subject: Re: [FFmpeg-user] How to filter VHS cassette artifacts

On Fri, Dec 7, 2018, at 10:33 AM, Ulf Zibis wrote:
> Hi,
>
> I have a VOB-file, originally recorded from a VHS-Kassette.
>
> On the upper edge I see a black line from left to the middle.
>
> Approximately 5 lines from bottom I see 2..3 other horizontally
> shifted flickering lines.

The band of garbage on the bottom looks like head switching noise.

https://nam03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbavc.github.io%2Favaa%2Fartifacts%2Fhead_switching_noise.html&amp;data=02%7C01%7C%7C459e23486ea0482e56a308d65e1cfcb3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636799875916584760&amp;sdata=ao44JID%2F0L8fO9FWmvsrFXYrRela7Vk7r%2FJ%2BGAFhKAc%3D&amp;reserved=0
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