Masking PAL capture

[pharries]

I am capturing PAL S-VHS tapes with a Canopus ADVC-100.
The VCR is a high end Panasonic with a built in TBC
I am getting garbage at the very bottom of the frame.
I gather this it data that is normally not seen on screen. The canopus web site states that this is normal with PAL capture. I never have had a problem with NTSC.
This garbage does interfere with MPEG compression however (it requires a lot of bits to code for random garbage).
How can I mask off the very bottom of the frames?
I have the following software:-
Scenalyzer
Adobe Premiere
Main Concept and CCE encoders
TPMGenc Plus
Would buy another product if not very expensive.
Thanks

[FulciLives]

Hello

I do all my mpeg1/mpeg2 encoding with TMPGEnc Plus 2.5
It has a clipping/masking feature built-in. The best thing would be to use the masking feature I think. It is very easy to use. When you are in the PROJECT WIZARD mode you will see the "CLIP FRAME" option on PAGE 3 of the PROJECT WIZARD settings.

If you are doing it manually without the PROJECT WIZARD then CLICK on settings which brings up the MPEG SETTING dialog box. This box has a bunch of TABS across the top and one of the tabs says, "ADVANCED" and that is where you will find the "CLIP FRAME" option.

Again you can clip or just mask the image. In fact I was just playing around with TMPGEnc and it is probably better to CLIP than to MASK because if you CLIP the bottom it will then center the image so for example if you cut 10 pixels (or lines) from the bottom the image will center with 5 lines extra on the top (black "dead" space) and 5 lines extra (black "dead" space again) on the bottom. Because of TV overscan the black should never show up on the TV (assuming you aren't CLIPPING too much from the bottom that is). If you mask the bottom then the top stays at the top and you have all 10 "masked" lines (black "dead" space again) at the bottom and that MIGHT show up on the bottom of the TV screen even with overscan.

If you want too you can also do this in an AVISynth AVS script. Simply clip the bottom of the frame by however many pixels you need to cover up the distorted part.

Let us say that as an example you need to clip 10 pixels or lines off of the bottom. Here is how you would do it in the AVS script:

crop(0,0,720,566)
AddBorders(0,0,0,10)

As you know PAL has a D1 resolution of 720x576 so the crop command here cuts 10 pixels (or lines) from the bottom then the AddBorders line restores those lines (with black) so that you get back to the proper height of 576

This AVS script method of course assums that the canopus captures at 720x576 for PAL captures or that you resize it to that if the capture size is less (such as 640x480 or whatever).

- John "FulciLives" Coleman

If you want to use the AVS script method and "center" the clip after the crop command then do this for the AddBorder command:

AddBorders(0,5,0,5)

This will put 5 lines of black on the top and 5 lines of black on the bottom.