At 07:44 PM 6/3/2000 -0500, you wrote:
On the scope, I see the video signal shows up like this: (adventure
startup screen)
+0.75
_________________
XXX XXX
0 | |
| XXXXXXX------- ---------
| | |
-------
-0.75
Is this a vectorscope/waveform pattern?
Could Glenn, (or someone else) give us a lesson in what the parts of this
signal are, and which parts the TV is actually responding to?
I don't know about video down to the individual scanline. I do know that
video has various properties, like black level, hue, saturation.. When
calibrating video you make sure the darkest (lowest) and brightest
(highest) video line up with the prescribed settings. To compare this with
audio, the middle part becomes the effective dynamic range of the
image. The video level, contrast, and brightness adjust this range,
compressing, expanding, and sliding it around.
Composite video has a luminance and chrominance attribute. Both of them
are waves intertwined kinda like stereo audio. This was done in order to
add color to B&W NTSC without breaking backwards compatibility. As this
gets decoded, noise or crosstalk is introduced, which is what we see as dot
crawl and fuzziness and such. The color itself is determined by the phase
shift of the chrominance signal. I think the saturation is determined by
the depth of the wave. The 2600 therefore, in order to generate color
video, needs only to generate this basic color wave and then modify its
phase and amplitude. Color is therefore 16 degrees of delay of the color
signal.
Glenn Saunders - Producer - Cyberpunks Entertainment
Personal homepage: http://www.geocities.com/Hollywood/1698
Cyberpunks Entertainment: http://cyberpunks.uni.cc
--
Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/
