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Re: IIgs RGB to YPbPr Component experiment
jsnospam@cimmeri.com wrote:
Linards Ticmanis wrote:
I wonder why they never caught on in the US? Here in Europe you'd be
very hard pressed to find any non-portable TV set that doesn't have an
RGB input.
When did you all start having RGB via SCART? And did you have
consumer devices that output RGB?
I think here in the USA, the only consumer devices that might have
benefitted from RGB video would have been the laserdisc, and possibly
SVHS.. until the DVD came out. But I don't know if these early formats
internally had separate color streams. They might have been recorded
in NTSC video? However, LD and SVHS usually had S-Video out. So
maybe Luma and Chroma streams?
Only after DVD machines (esp. those with progressive scan 480p) with
their separate color streams became available, did we start seeing TVs
with Component RGB video. Some TVs prior to progressive scan had
Component RGB 480i inputs, but I never saw any difference between
S-Video input and Component RGB 480i. Maybe the same people who can
hear the difference between 16ga. zipcord and expensive Canari speaker
cables can also see differences with 480i Component RGB.
So I think that these negligible gains for 480i video via RGB are why
we never had pervasive RGB until more recently: it just wasn't a big
enough improvement for a mass market that wants convenience over
performance (eg. VHS vs. Beta).
Certainly, though, once HD DVD becomes commonplace, component video or
digital video will certainly provide the dramatic, convincing
improvements, and will be necessary as well for 1080i, 720p, etc.
The push for digital has many reasons, but I note that again, cabling
convenience is one of them. I've got 5 cables handling analog [sound
+ RGB Component], versus one digital HDMI cable doing the same thing.
I agree that the benefit of an RGB or component connection is marginal
at best with SD TV. Even the improved bandwidth of SD DVDs is easily
supported with S-Video.
Looked at from a system perspective, an RGB connection saves matrixing
to YUV in the monitor, but that is a minor cost (comparable to RGB-->YUV
matrixing we have been discussing). And the saving comes with other
costs: 1) every video source (DVD player, tuner, etc.) must matrix its
native YUV to RGB before transmission, cancelling any monitor savings
many times over, and 2) any level inaccuracy in RGB tranmission results
in hue errors, while level inaccuracies in YUV transmission are much
less perceptible, tending more toward changes in contrast or saturation
than hue shifts.
Further, all three (RGB) channels must be sent with high bandwidth,
while in YUV, only the Y channel *requires* high bandwidth.
As things go digital, many of these attributes persist, with Y getting
more bits than U and V channels, while RGB would demand a more nearly
equal sharing of bits.
The cabling problem is actually unique to North America, where we have
persistently defaulted to the single-channel "RCA connector" for all
baseband coaxial signals. This means that even a combined cable must
terminate in a "three-headed" RCA fanout!
We could have had single video cables, and even single audio+video
cables, a long time ago, but the only thing that competing manufacturers
could agree on was...the default RCA connector. ;-(
Differential digital signalling certainly allows much smaller, simpler
cables. Too bad it arrives in the form of fully handshaked, mutually-
authenticated, encrypted interfaces (HDMI).
-michael
Parallel computing for 8-bit Apple II's!
Home page: http://members.aol.com/MJMahon/
"The wastebasket is our most important design
tool--and it is seriously underused."