Overscan problem ??

[cd090580]

I've captured a music video from an old VHS tape and I'd tried to convert it to DVD.

I captured it at 480*576 (25 fps) and I convert to DVD (720*576)

The conversion is successfull and it plays fine on PC and TV.
But on my TV, the borders of video are missing.

The captured video looks like this (the picture may take some seconds to display, the server is not very fast:


But when I plays in on my TV, the most noticable is the logo on the upper left. On the TV the "S" letter is half cut in width and about a quarter of the height is also cut.

So how many pixels should I add to avoid the overscan.

Here is the current settings I use to convert it.

Source: AVI 480*576 (captured) MJpeg.
Destination: DVD 720*576 encoded with MainConcept at average bitrate of 4400.

I use the following avisynth script:

avisource("d:\soap.avi",false)
letterbox(8,8,0,0)
fadeout(15)
limiter()

I let Mainconcept do the resize. Maybe it will be better to do it with avisynth ?

So which settings do I need to do a correct resize and avoid overscan ?

Thanks.

[Tommyknocker]

I've captured a music video from an old VHS tape and I'd tried to convert it to DVD.

I captured it at 480*576 (25 fps) and I convert to DVD (720*576)

The conversion is successfull and it plays fine on PC and TV.
But on my TV, the borders of video are missing.

The captured video looks like this (the picture may take some seconds to display, the server is not very fast:


But when I plays in on my TV, the most noticable is the logo on the upper left. On the TV the "S" letter is half cut in width and about a quarter of the height is also cut.

So how many pixels should I add to avoid the overscan.

Here is the current settings I use to convert it.

Source: AVI 480*576 (captured) MJpeg.
Destination: DVD 720*576 encoded with MainConcept at average bitrate of 4400.

I use the following avisynth script:

avisource("d:\soap.avi",false)
letterbox(8,8,0,0)
fadeout(15)
limiter()

I let Mainconcept do the resize. Maybe it will be better to do it with avisynth ?

So which settings do I need to do a correct resize and avoid overscan ?

Thanks.

I don't know the answer to your question, but who is that?

[iantri]

This is extremely strange. You should never have to do this on captured video.

When you watch that channel on the TV, is it cut off? If it is, then it is a problem with the TV station. However, if it looks right on your TV but looks cut off when you play back the captured MPEG, there is another problem.

What program are you using? Does it compensate for overscan (even when capturing)? If so, you need to turn that off.

What encoder?

[cd090580]

No, I don't do any compensation (it's captured from a VHS tape).

To make simple here is how I do the capture:

VCR -> composite input of my WinTv card
VCR(audio) -> line input of my soundcard
Capture at 480*576 with virtualdub codec Mjpeg Quality 18

The encoder is Mainconcept Mpeg Encoder

[cd090580]

I've tried to add a 8 pixels border all around the video but now the right part is missing

How much do I resize to get the correct ratio. The video source is 4:3 and destination is of course 4:3.

Here is my modified script:

Source resolution is 480*576.

avisource("d:\soap.avi",false)
lanczosresize(704,560)
addborders(8,8,8,8)
fadeout(15)
limiter()

Does it seems correct because it takes some time to encode the video ?

Thanks.

[iantri]

I suppose what I am saying is that this should not be happening, and it would be best to fix the problem at the source. (The Avisynth script should work to add borders, by the way)

Does it look cut off when you watch the tape on a TV?

[dphirschler]

Try resizing to 704x576.


Darryl

[cd090580]

Does it look cut off when you watch the tape on a TV?

When I watch the tape is perfect (no part is cut off).

It's only when I watch the result on DVD (on the computer no prolem).

My TV is a 4:3 one and the dvd player is set to 4:3 Letterbox.

The DVD is authored with TMPGENC DVD Author

[iantri]

Perhaps you accidentally set some values wrong in MainConcept?

Without the Avisynth script lines to pad the image and add borders try the following:

Using the script:

AviSource("d:\soap.avi",false)
Trim(0,200) # we only need a few seconds, save encoding time!

Don't bother with an audio source. Mpeg type: DVD, Video mode: PAL. You should have cropping (in Mainconcept) set to zero all around. Height should be 576, centre 288. Width should be 720, centre 360.

Author the DVD. Does it look cut off? Try the following AviSynth script:

AviSource("d:\soap.avi",false) 
Trim(0,200) # we only need a few seconds, save encoding time!
BilinearResize(720,576)

Don't bother with an audio source. Mpeg type: DVD, Video mode: PAL. Don't set cropping or resize set in Mainconcept. Encode. Author. Is it still cut off?

This is very strange, because your source video is fine -- the way you are capturing should not have caused any cropping, and it LOOKS fine -- the text is far enough away from the edges that it shouldn't get cut off (well, resize to 720x576 and you will see that.. it is difficult to tell when the video is squashed like that, but it should be enough. Certainly makes no difference for the height and it is fine).

[junkmalle]

You are losing the left edge of the picture when you capture (probably the right too). There's almost always some black border and noise at the left edge when you capture but your sample image has clean picture all the way to the edge. And the logo is way too close to the edge -- no broadcast would ever put the logo that close to the edge of the frame.

Overscan will typically consume 30 to 60 pixels on each edge of a 720x480/576 frame -- depending on the TV. If you can't capture the video without cropping you'll have to scale and pad with those numbers in mind.

[iantri]

While it is tight, the logo is just within the Action Safe area (5%). I've seen TV stations do worse (my local station CBC station sticks text that says "Channel 22" below the main network logo, so far down that it is badly cut off on any set. Their productions standards are really low, though..)

Visually checking it (by authoring the image and playing back on a DVD player) shows me that unless the poster's TV set is REALLY mal-adjusted it shouldn't get cropped, or at least not nearly as bad as described.

[cd090580]

To make it simplier (because I think I don't explain correctly the cut zone).

Here is how it displays on my Tv after encoding.

[junkmalle]

The action safe area is usually considered to be about 5 percent on all sides. The title safe area is usually 10 percent on all sides. For a 720 pixel wide image the title safe area excludes 72 pixels at each edge. For a 480 pixel wide image it's about 48 pixels at the edges. Your logo is only about 24 pixels from the left edge of the image you posted.

[iantri]

Ah.

Yes, that is exactly how it looks for me on my TV.

Something must be wrong with your capture settings, then, if there is more to be seen around the edges on the original tape.

Anyway, you can do the padding using the AviSynth script you posted earlier, but it will need modification to do the interlaced video properly. I'm going to use different padding values, because your capture card seems to have removed exactly 5%.

The following should work:

EDIT: Ack! the short line lengths in the forum caused the comments to look screwy.. paste into notepad and it will look fine.

AviSource("d:\soap.avi",false)

SeperateFields()  # fields are half-height.. remember when doing resize
LanczosResize(668,274) # 704-5% = approx 668, 288-5% = approx 274
Weave()

# I am using 704 as a figure because 720x576 video has the same pixel
# aspect ratio as 704x576 video, just with more on the sides.  If your 
# card captured properly, the 480x576 video's PAR should be 
# proportional to a 704x576 capture.  One can then pad out to 720, 
# which should theoretically make sure that the video plays back 
# with perfect aspect ratio on any player.

AddBorders(26,14,26,14) 

FadeOut(15)

# the Limiter() line shouldn't be used as MainConcept will will do a
# conversion from 0-255 scale to 16-235 scale, when video is fed
# through the way you have set up.  Limiting it while it is still 0-255 
# will cause an unnecessary loss of contrast.

BTW, junkmalle, I am aware of the difference between action safe and title safe areas, I was just pointing out that it was possible that the original broadcast could have been too tight. It appears, though, that this is not the case.

Anyway, hope I didn't make any large math errors in that script, with the exception of the unavoidable rounding errors.

[cd090580]

Thx a lot for all the informations. I try a reencoding tis weekend.
I hope it will work