Harsh, "aliased" sound with digital TV converter box.

Arny Krueger wrote:
"Arny Krueger" wrote in message

"trotsky" wrote in message
news%[email protected]_s21
Arny Krueger wrote:
"trotsky" wrote in message
news:[email protected]_s21
Did Dolby do their homework and
do sufficient blind tests to "prove" that their codec
was transparent to people?
AFAIK, Dolby never claimed that DD was perfectly
transparent.
And your working definition for "perfectly transparent"
is what, exactly?
Passes a bypass test with under any relevant test
condition without audible alternation.

Correction:

Passes a bypass test with under any relevant test
condition without audible alteration.


You're still not speaking English.

"William Sommerwerck" wrote ...
Not so. Think about it. Saturation (which is what the amplitude of the
color-difference signal represents) "never" (well, hardly ever) changes
as
rapidly as luminance.

You need to be careful here. While saturation is a function of color
differences, it needs to be normalized by the intensity.

That is PRECISELY the point. Subtracting Y from
R, G, or B provides the normalization and produces a
saturation -- color-difference -- signal from which
brightness information has been removed. This is what
we want.

The original reason for even matrixing R-G-B into Y-*-*
was to preserve monochrome compatibility for those who
have B&W receivers. And then to produce a color signal
that could be relatively easily compressed and encoded
onto a subcarrier and then decoded at the receiver.

This is not necessarily "what we want" for those who prefer
their video ucompressed and uncompromised. It was a
kludge workaround to fit the 15-pound color signal into the
5-pound monochrome sack (channel bandwidth).

More than 50 years ago, Electronics magazine published
pictures of the NTSC color signals, based on real scenes.
The colors are completely "flat" -- they are of constant
saturation, with no variation in brightness.

Then you were looking at the color difference signals. (Pb,
Pr, etc.) after the luminance (Y) had been removed. We
will have to disagree whether to call those signals "color".
They are maybe "color difference" at best. If you saw the
original Red Green Blue signals, they have plenty of contrast.

It's important to understand that NTSC and PAL are
non-redundant systems. None of the three signals contains
information present in another.

It is equally important to remember that in NTSC and PAL,
the color-difference part of the signal is artifically frequency-
limited to save bandwidth during transmission/storage. Any
time you execute this kind of lossy compression, you irretrievably
lose information. Whether you are talking about audio or video.

Richard Crowley wrote:

The original reason for even matrixing R-G-B into Y-*-*
was to preserve monochrome compatibility for those who
have B&W receivers. And then to produce a color signal
that could be relatively easily compressed and encoded
onto a subcarrier and then decoded at the receiver.

There's really no future in it. People don't really _want_ color
anyway. I'm waiting until it's perfected before I buy a color set.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote ...
Richard Crowley wrote:
The original reason for even matrixing R-G-B into Y-*-*
was to preserve monochrome compatibility for those who
have B&W receivers. And then to produce a color signal
that could be relatively easily compressed and encoded
onto a subcarrier and then decoded at the receiver.

There's really no future in it. People don't really _want_ color
anyway. I'm waiting until it's perfected before I buy a color set.

You missed the peak. Even as screen sizes increase and we
get "High Definition" 16x9 video, lossy compression is being
cranked up and turning video into watery puddles of what
used to be pictures.

I was trying to watch "Bone Detectives" on the Discovery
Channel on DishNetwork last night and the compression
was so high that it couldn't even keep up with the guy
walking across the sand. It was almost un-watchable on
my 13-inch video monitor. It would have looked like water-
damaged wallaper on a big screen TV.

For the decline of technical quality, along with the decline
of programming worth watching, I'm letting my satellite
subscription just expire.

"Richard Crowley" wrote in message
...
"William Sommerwerck" wrote ...
Not so. Think about it. Saturation (which is what the amplitude of the
color-difference signal represents) "never" (well, hardly ever)
changes
as
rapidly as luminance.

You need to be careful here. While saturation is a function of color
differences, it needs to be normalized by the intensity.

That is PRECISELY the point. Subtracting Y from
R, G, or B provides the normalization and produces a
saturation -- color-difference -- signal from which
brightness information has been removed. This is what
we want.

The original reason for even matrixing R-G-B into Y-*-*
was to preserve monochrome compatibility for those who
have B&W receivers. And then to produce a color signal
that could be relatively easily compressed and encoded
onto a subcarrier and then decoded at the receiver.

This is not necessarily "what we want" for those who prefer
their video ucompressed and uncompromised. It was a
kludge workaround to fit the 15-pound color signal into the
5-pound monochrome sack (channel bandwidth).

More than 50 years ago, Electronics magazine published
pictures of the NTSC color signals, based on real scenes.
The colors are completely "flat" -- they are of constant
saturation, with no variation in brightness.

Then you were looking at the color difference signals. (Pb,
Pr, etc.) after the luminance (Y) had been removed. We
will have to disagree whether to call those signals "color".
They are maybe "color difference" at best. If you saw the
original Red Green Blue signals, they have plenty of contrast.

It's important to understand that NTSC and PAL are
non-redundant systems. None of the three signals contains
information present in another.

It is equally important to remember that in NTSC and PAL,
the color-difference part of the signal is artifically frequency-
limited to save bandwidth during transmission/storage. Any
time you execute this kind of lossy compression, you irretrievably
lose information. Whether you are talking about audio or video.

I'm not going to beat this to death, because what I've said is 100% correct,
and a bit of though will confirm that.

Simply limiting the bandwidth of a signal is not "compression" in any
ordinary sense. The real compression -- which is not lossy -- is subtracting
Y from the primary color signals. This permits the color-difference signals
to more "advantageously" use their limited bandwidth.

I've stopped discussing this. A few nights from now, when you're mulling
this over in bed, and the light goes on, you can post a "Oh, yeah... Now I
get it." response.

"William Sommerwerck" wrote ...
I'm not going to beat this to death, because what I've said is 100%
correct,
and a bit of though will confirm that.

Simply limiting the bandwidth of a signal is not "compression" in any
ordinary sense.

It most certainly is information compression in the truest sense.
The people that worked on the telephone system have known
it for nearly a century. Perhaps you need a bit more thought.

The real compression -- which is not lossy -- is subtracting
Y from the primary color signals. This permits the color-difference
signals
to more "advantageously" use their limited bandwidth.

That is not compression at all. That is simply changing the
format of the information. Your view of this appears to be
fundamentally incorrect.

I've stopped discussing this. A few nights from now, when you're mulling
this over in bed, and the light goes on, you can post a "Oh, yeah... Now I
get it." response.

Perhaps YOU will have that experience. I don't need it.

"Richard Crowley" wrote in message
...
"William Sommerwerck" wrote ...

The real compression -- which is not lossy -- is subtracting
Y from the primary color signals. This permits the color-difference
signals to more "advantageously" use their limited bandwidth.

That is not compression at all. That is simply changing the
format of the information. Your view of this appears to be
fundamentally incorrect.

Changing the format is one way of presenting the information in a
more-compact, more-useful fashion.

The "compression" produced by subtracting the luminance is the removal of
redundant information.


I've stopped discussing this. A few nights from now, when you're mulling
this over in bed, and the light goes on, you can post a "Oh, yeah... Now
I
get it." response.

Perhaps YOU will have that experience. I don't need it.

You will. YOU WILL...

On Feb 28, 1:56 pm, (Scott Dorsey) wrote:
In article , pj wrote:
Scott Dorsey wrote:
William Sommerwerck wrote:
Since the s-video output and the composite output are both NTSC,
it is impossible for either the s-video output or the composite output
to have *more* output than the NTSC output -- they *ARE* NTSC
outputs.
This might be true in practice, but "it ain't necessarily so".

How would they not be NTSC?

A case for S-Video in preference to Composite:

Oh, there are many strong cases for S-Video over composite. But both are
NTSC. The S-Video is also NTSC, it's just not RS-170.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Unless the S-video signal is based on the PAL standard! :-)

On Feb 29, 1:51*pm, "William Sommerwerck"
wrote:
"Richard Crowley" wrote in message

...

"William Sommerwerck" *wrote ...
The real compression -- which is not lossy -- is subtracting
Y from the primary color signals. This permits the color-difference
signals to more "advantageously" use their limited bandwidth.
That is not compression at all. That is simply changing the
format of the information. Your view of this appears to be
fundamentally incorrect.

Changing the format is one way of presenting the information in a
more-compact, more-useful fashion.

The "compression" produced by subtracting the luminance is the removal of
redundant information.



I've stopped discussing this. A few nights from now, when you're mulling
this over in bed, and the light goes on, you can post a "Oh, yeah... Now
I
get it." response.
Perhaps YOU will have that experience. I don't need it.

You will. YOU WILL...

Just FYI, the transcoding from RGB to Y, R-Y, B-Y is a lossless
transform and does not one iota of bandwidth change _until_ you run
the components through the bandpass filters on the way to the balanced
modulators. Also, there most certainly is equiband encoding going on.
I was working on a BetaCam SP just yesterday and the filters in the
encoder have the same part numbers. How could they be differrent? The
Sony broadcast cameras are the same story as is the Accom D-122
digital encoder - all of which were VERY common in Hollywood. You'd
have a mauch harder time finding a true IQ encoder. As I said earlier,
the last IQ encoder I saw was an RCA studio camera from 1976

GG

jwvm wrote:
On Feb 28, 1:56 pm, (Scott Dorsey) wrote:
In article , pj wrote:
Scott Dorsey wrote:
William Sommerwerck wrote:
Since the s-video output and the composite output are both NTSC,
it is impossible for either the s-video output or the composite output
to have *more* output than the NTSC output -- they *ARE* NTSC
outputs.
This might be true in practice, but "it ain't necessarily so".

How would they not be NTSC?

A case for S-Video in preference to Composite:

Oh, there are many strong cases for S-Video over composite. But both are
NTSC. The S-Video is also NTSC, it's just not RS-170.

Unless the S-video signal is based on the PAL standard! :-)

Or SECAM for that matter!
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."