On Sun, 6 Nov 2005, [UTF-8] Bernhard Fr??hmesser wrote:
> Hmm, i think that one is a bit to expensive for me :-) And i am not sure
> if it would run on my Apple iBook G4, so far i think there is no version
It would run on a iBook G4. The render times would be somewhat lengthy
though :)
> for Linux, where i do all video stuff.
That's why I've moved all of the video stuff to OSX :)
> Well, in the sourcevideo there is a black border on the left and bottom.
How large is the border?
Use y4mshift to center the active image and blacken the borders. If
you're working with 4:2:0 there are contraints on the granularity
of shifting (multiple of 2 horizontally, multiple of 4 vertically).
> > If the final output is for "DVD" (and viewing on a TV) there are a
> The final output should be for DVD (to store) and also for PC, as i need
Ok, then the DVD frame size is a constraint that must be observed.
> > Crop to 704xN - that will save ~2% on the encoding time and save a
> > few bits (which can be used for the image rather than the borders).
>
> 704? I thought DVD-PAL is 720?
> For all commercial DVD i own i get 720x576 when i watch them via mplayer
> or xine. Is 704 the NTSC variant?
They're lazy and don't crop the extra pixels ;)
No, 704 is not NTSC specific.
The DVD frame (like the DV frame) includes a few extra pixels on
each side. Broadcast is 704xN where N is either 480 or 576
http://www.dvddemystified.com/dvdfaq.html#3.4
DVD frame size is 720x576, 704x576 or 352x576 (with corresponding
x480 for NTSC).
There is a 3rd edition of the DVD Demystified book due out now - the
"available on the shelf" mentions November. I have a copy ordered so
it should be arriving soon.
Analog TV is 704x576 (or 704x480). So when an analog->digital
conversion is done (with a Canopus DV converter or other capture
device) you will see 8 'garbage'/black pixels, 704 active (the real
image) pixels, and 8 black/garbage pixels. Depending on the stability
of the signal, and other factors, the active 704 may not be exactly
centered. That's when y4mshift is useful - it can center the image
and blacken the borders in one step. Then later you can crop or not.
The left and right 8 pixels can either be 1) cropped or 2) turned to
black (they're nothing but noise/junk which will waste a lot of bits
during encoding).
The bottom 6 to 8 pixels of an capture from a VHS tape are trash
from the VCR. Sometimes the top 2 to 6 lines are just as bad. Since
the number of lines is fixed (480 or 576) and upscaling is Bad for
quality the only thing that should be done is blacken the top and
bottom lines (so the encoder doesn't spend bits encoding trash).
At least a couple percent at the top and bottom are not visible at
all on a TV (unless you have a production monitor with "underscan"
capability).
TVs overscan a lot - 5% is considered low - so on a TV you don't see
30+ pixels at the edges. Out of 720 pixels on a line you're lucky
to see 600 on a TV.
> > Preprocess the data with FCP - I've found the filters and plugins for
> > very effective (especially the color correction and level adjustments).
>
> Unfortunately there doesn??t seem to be a version for Linux...
Rather than wait for the tools to be available (which could be a
Very Long Wait) I shifted to an environment with a richer set of
tools. Combining the two worlds of free and commercial has worked
out well.
> Hmm, so far that looks a bit better, but there are still some errors,
> pay attention at the orange flag in the bottom of the image as well as
I'm not 100% certain but I am fairly sure that is being caused by
upscaling interlaced material. That's a side effect of going from
564 to 576.
> Is there a method to get rid of these small lines?
Don't upscale interlaced material is the only thing that comes to
mind. The source is interlaced so still images that capture two
fields will always show "lines" - nothing can be done about that.
But upscaling interlaced material will make things look worse (in
addition to skewing the aspect ratio).
When creating still images from interlaced sources you're going
to get 2 fields from different points in time - so if there's any
motion then you'll see "lines" (the "comb" effect). That's the
nature of interlaced video. You could try to find a scene with
no motion - a still image then would look better.
You could try using 'yuvdeinterlace' - maybe that will do what you
want. If you still want to upscale then deinterlace first - that
should minimize the artifacting.
Good Luck!
Cheers,
Steven Schultz
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