On Tue, 24 Aug 2004, Anne Wilson wrote:
> On Tuesday 24 Aug 2004 21:23, Selva Nair wrote:
> > On Tue, 24 Aug 2004, Anne Wilson wrote:
> > Out of curiosity, how did you end up with a 768x576 interlaced PAL avi?
That's the square pixel PAL full frame size of course ;)
768/576 = 4/3
> My capture card is a DC10+ under v4l - that's the resolution it captures at
> full size. On my previous small project I used -d 2, but I think on this one
> I used -d 1 in lavrec.
Yep - and DC10+ cards generate square pixels (or, if they can provide
Rec.601 pixels then the drivers/software aren't requesting that
format). Thus the need to resample/scale to the DVD frame size.
This:
http://www.mir.com/DMG/aspect.html
and the paragraph with:
An image with a standard display aspect ratio of 4:3 (i.e. TV) with 576 lines
(i.e. PAL) would thus have:
* 768 square pixels per line, or
* 702+54/59 non-square 59:54 pixels per line
So, a DVD frame of 720x576 is really (and we'll round up a pixel or so)
a 704x576 area inside a 720x576 frame! You'll have 8 pixels of black
on each side in a correctly resampled 768x576 to 720x576 frame. Don't
worry about seeing the black borders though - they'll be hidden by
the thief (TV overscanning) ;)
If you have y4mscaler this is what should do the job for you:
... | y4mscaler -I sar=1:1 -O sar=PAL -O preset=DVD -O option=sinc:4 | ...
Of course you could just go with the 704x576 frame size - just change
the "-O preset=DVD" to be "-O size=704x576", I think that should do
the trick.
Good Luck!
Steven Schultz
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