VHS Capture, junk at the bottom of the screen (Overscan)

[BassKozz]

I've captured a few VHS tapes to my computer, and they all have the same junk on the bottom of the screen (when played on my computer). I've learned from DigitalFAQ (http://www.digitalfaq.com/dvdguides/capture/understandsource.htm#overscan) that this is just OverScan:

What is overscan?
A tv set only show about inside 93 percent of the available image. The rest is hidden behind the box surrounding the tube. This is called overscanning. Broadcasters and others in video know full well that this happens, so rest assured that you are not missing much. In fact, the overscan area often contains little more than black bars or video errors, and should be seen as a courtesy moreso than a hindrance. Recorded formats (VHS, S-VHS, etc) suffer the most, in terms of overscan noise. Broadcast formats often have black bars in the overscan. Most satellite streams have noise in the upper overscan, visual residue from non-video parts of the data stream.

You never see this portion of the image on a tv set, however computers have no such mechanism. So, sadly, many people feel they must "crop" or "mask" out the noise. In most cases, it is simply a lack of knowledge from amateurs online, thinking they have a "bad quality" signal. So they seek to mask it, which is fine. Or more often, crop it, which is undesirable.

So I figured I should probably "MASK" this area on the bottom of my video's as I will be sharing them on the internet (people will be watching these on their computers and not their TV's).

My question is what's the best (and easiest to use) application to use to "mask" this bottom portion of my videos?

Thanks,
-BassKozz

[mats.hogberg]

Well, you'd have to reencode the video to achieve that, and what tools to use depends on video format.
What format do you capture in, and what format do you want to distribute your video in?

/Mats

[thecoalman]

The reason for masking is because if you're using the video on a DVD cropping it will require that it be resized to a DVD compliant resolution after you crop it which opens up a can of worms as far as quality is concerned. If it's just for computer playback this is no longer an issue since the the resolution is irrelevant. Actually it will be beneficial because you will be reducing the resolution allowing for lower bitrate and smaller file size.

Windows Media encoder has an option for cropping while you're encoding killing two birds with one stone.

[BassKozz]

Well, you'd have to reencode the video to achieve that, and what tools to use depends on video format.
What format do you capture in, and what format do you want to distribute your video in?

/Mats

I captured in MPEGII 8,000kbps (CBR) 352x480.
I will be distributing in both MPEGII (I'd like to keep as much quality as possible), as well as DivX.

The reason for masking is because if you're using the video on a DVD cropping it will require that it be resized to a DVD compliant resolution after you crop it which opens up a can of worms as far as quality is concerned. If it's just for computer playback this is no longer an issue since the the resolution is irrelevant. Actually it will be beneficial because you will be reducing the resolution allowing for lower bitrate and smaller file size.

Windows Media encoder has an option for cropping while you're encoding killing two birds with one stone.

From what it said on DigitalFAQ it says cropping is undesirable, and masking is better (see quote in original post). And I won't be putting these video's on DVD... they will be shared on the internet (people will use their computers to watch).

So I'd rather Mask then crop.

Thanks for the help guys,
-BassKozz

[lordsmurf]

You can crop if these BOTH of these criteria apply:

1- If the video will NEVER AGAIN be shown on a tv set. It will never be converted back to DVD. This is purely for web viewing, from now to the end of time.

2- The cropping is the new size. In other words, if you source is 320x240, and you crop 10 pixels off each side, then the new video needs to be 300x220. Do not crop AND enlarge back to 320x240.

Remember the context of the digitalFAQ.com guide. It's discussing the overscan as it relates to viewing and working with sources intended to be encoded for viewing on a tv set again.

I can see you already plan to resize from 352x480 to something smaller and 1:1 aspect (4:3 sized). I would convert to a 4:3 first, before cropping. Something like 400x300 would be nice. Then crop off your pixels (in multiples of 8 pixels), and end up with something of decent size, about 384x288 would be one target.

Resizing after a crop causing aliasing and other quality issues.

It can get complicated when you're trying to crop, and not enlarge, and retain 4:3 image, especially when working in the confines of an MPEG that requires an 8x8 structure.

Masking is always easy, just use TMPGEnc and the crop tool. Instead of chopping off pixels, have it mask. VirtualDub can also do it. Use both the null transform and resize filter together.

[TBoneit]

Note also that it isn't called overscan. Overscan is what keeps you from seeing it on a TV set. Big Difference.

What you see at the top of the picture is data that is being transmitted in lines of video and CC data.

If at the bottom of the screen on VHS then it is head switching.

Cheers

[thecoalman]

I captured in MPEGII 8,000kbps (CBR) 352x480.
I will be distributing in both MPEGII (I'd like to keep as much quality as possible), as well as DivX.

One thing to keep in mind is your audience, depending on who they are some to many will not have a mpeg2 or Divx codec installed. I'd skip the MPEG 2 altogether and use MPEG1 if you want to provide a video in mpeg format since everyone will be able to decode it. The only realistic benefit MPEG2 provides is that it's DVD compatible but since that is not an issue you don't need it.

Quality is not an issue either, Divx or WMV will look just as good but in a smaller package. My personal choice is WMV because most people will be able to play it right off the bat.

From what it said on DigitalFAQ it says cropping is undesirable, and masking is better (see quote in original post).

As LS said that statement is in the context for creating DVD's. Again you can perform all these oprations in one swipe with Windows Media Encoder... but whatever floats your boat.

[BassKozz]

I tried Windows Media Encoder for the first time and I hate it

It locked up on me and caused my CPU to max out. Is there another program I can use to convert to MPEG1 or WMV ?
And get rid of the "head switching" ?

[thecoalman]

It locked up on me and caused my CPU to max out. Is there another program I can use to convert to MPEG1 or WMV ?

A p2? :P Any conversion you make is going to take a very long time. I'm not going to give specifics but a 1 hour clip with a p2 your timeframe can be measure by the day or days. Anyhow I doubt any other program is going to give you any better results. I've used that program hundreds of times and have never had it lock up on me. You can try Windows Movie Maker but that is still going to be using the same encoding engine but with less options.

As far as converting to MPEG1 you can do that with TNPGenc indefinitely if I remeber correctly. It only locks you out of the MPEG encoding after 30 days.

I'll assume you have a harware capture card as there is no ther way you would have been able to capture them in the first place. I'd suggest recapturing at very low bitrate MPEG1 and leave it at that or qwork on a faster computer. A p2 is sorely underpowered for any video processing, my day or days comment wasn't a joke.