[MPlayer-users] Converting DivX4 -> MPEG ?

[Novak Levente]

Tuukka Toivonen tuukkat at ee.oulu.fi wrote:

>>I told about horizontal, not vertical lines, because that's how it's
>>called in the VCR/camcorder world. It corresponds to the _horizontal_

>Unfortunately I lost my clue. Everything I understand, is that the
>more horizontal (scan)lines one has, the more vertical resolution he has.

>The more vertical resolution one has, the more the display can show
>distinct horizontal lines.

>You are saying otherwise, but I just don't get it.

>>resolution of an analog output. For most PAL Hi8 camcorders, the
>>resolution is 480 analog horizontal lines per 576 of vertical scanlines

>Scanlines are horizontal! From left-to-right.

OK, it is not very easily understandable because this silly analog source
parlance.

PAL Hi8 video resolution is 480x576, NOT 576x480! It has more resolution
vertically than horizontally. Additionnally, the vertical lines (what you
and everybody else effectively call lines) are "real" lines, e.g. there is
a sync signal which delimits them, so verically if you sample 576 lines,
you preserve the original resolution (eg. you don't need to sample 2x576
y-pixels with your grabber card).

On the opposite, the HORIZONTAL resolution of 480 is NOT in pixels, PAL is
an analogue broadcast standard! It is the visual "resolution" you get but
it is not directly related to the pixels (these are digital units).
Roughly speaking, the analog signal can vary 480-times during its
course from the leftmost to the rightmost part of its horizontal
trajectory through a horizontal scan session. And sadly enough this
_horizontal_ resolution is also called "line" (not a column as it would
seem more logical and you would call it).

In fact it is even more complicated, you should consult a dedicated
book/page if you are interested in the details.

In short, you have to sample twice the horizontal "analog resolution" but
the exact same vertical one to be on the safe side.

Levente