These days, every possible accessory seems to be "bluetooth" / USB
interfaced. But I've never seen a "USB" monitor advertised. (neither
bluetooth, of course) Neither CRT (who buys those!? :) ) nor LCD.

Why is that? A bandwidth limitation? Or a need that doesn't exist? I doubt
that is the reason since if I can want a USB headset why not a USB monitor?

Besides there are "good" quality headsets available even on bluetooth. Is
"acceptable-quality" sound transmission fundamentally a lower bandwidth
process than "acceptable-quality" images? What is the ratio of the max
bandwidth attainable over USB vs bluetooth vs "traditional-monitor-
connections".

I cannot think of any other peripheral that isn't available in a USB
version if not bluetooth. Do others have examples of they know? Just
curious....


--
Rahul

On Wed, 16 Jul 2008 01:17:57 +0000, Rahul rearranged some electrons to
say:

> These days, every possible accessory seems to be "bluetooth" / USB
> interfaced. But I've never seen a "USB" monitor advertised. (neither
> bluetooth, of course) Neither CRT (who buys those!? :) ) nor LCD.
>
> Why is that? A bandwidth limitation? Or a need that doesn't exist? I
> doubt that is the reason since if I can want a USB headset why not a USB
> monitor?
>
> Besides there are "good" quality headsets available even on bluetooth.
> Is "acceptable-quality" sound transmission fundamentally a lower
> bandwidth process than "acceptable-quality" images? What is the ratio of
> the max bandwidth attainable over USB vs bluetooth vs
> "traditional-monitor- connections".
>
> I cannot think of any other peripheral that isn't available in a USB
> version if not bluetooth. Do others have examples of they know? Just
> curious....

Example for a medium resolution:

1024 x 768 pixels x 24 bits per pixel x 30 frames per second
= 566 Mbits/sec.

USB 2.0 high speed = 480 Mbits/sec

Rahul wrote:
> These days, every possible accessory seems to be "bluetooth" / USB
> interfaced. But I've never seen a "USB" monitor advertised. (neither
> bluetooth, of course) Neither CRT (who buys those!? :) ) nor LCD.
>
> Why is that? A bandwidth limitation? Or a need that doesn't exist?
> I doubt that is the reason since if I can want a USB headset why
> not a USB monitor?
>
> Besides there are "good" quality headsets available even on
> bluetooth. Is "acceptable-quality" sound transmission fundamentally
> a lower bandwidth process than "acceptable-quality" images? What is
> the ratio of the max bandwidth attainable over USB vs bluetooth vs
> "traditional-monitor- connections".
>
> I cannot think of any other peripheral that isn't available in a USB
> version if not bluetooth. Do others have examples of they know? Just
> curious....

http://www.xbitlabs.com/articles/oth...g-sm940ux.html
http://www.everythingusb.com/samsung...0ux_11970.html

Google is not your enemy.

--
Shenan Stanley
MS-MVP
--
How To Ask Questions The Smart Way
http://www.catb.org/~esr/faqs/smart-questions.html

Rahul wrote:
> These days, every possible accessory seems to be "bluetooth" / USB
> interfaced. But I've never seen a "USB" monitor advertised. (neither
> bluetooth, of course) Neither CRT (who buys those!? :) ) nor LCD.
>
> Why is that? A bandwidth limitation? Or a need that doesn't exist?
> I doubt that is the reason since if I can want a USB headset why
> not a USB monitor?
>
> Besides there are "good" quality headsets available even on
> bluetooth. Is "acceptable-quality" sound transmission fundamentally
> a lower bandwidth process than "acceptable-quality" images? What is
> the ratio of the max bandwidth attainable over USB vs bluetooth vs
> "traditional-monitor- connections".
>
> I cannot think of any other peripheral that isn't available in a USB
> version if not bluetooth. Do others have examples of they know? Just
> curious....

Shenan Stanley wrote:
> http://www.xbitlabs.com/articles/oth...g-sm940ux.html
> http://www.everythingusb.com/samsung...0ux_11970.html
>
> Google is not your enemy.

Go a step beyond...
http://www.wi-fiplanet.com/news/article.php/3715636

--
Shenan Stanley
MS-MVP
--
How To Ask Questions The Smart Way
http://www.catb.org/~esr/faqs/smart-questions.html

Rahul wrote:
> These days, every possible accessory seems to be "bluetooth" / USB
> interfaced. But I've never seen a "USB" monitor advertised. (neither
> bluetooth, of course) Neither CRT (who buys those!? :) ) nor LCD.
>
> Why is that? A bandwidth limitation? Or a need that doesn't exist? I doubt
> that is the reason since if I can want a USB headset why not a USB monitor?
>
> Besides there are "good" quality headsets available even on bluetooth. Is
> "acceptable-quality" sound transmission fundamentally a lower bandwidth
> process than "acceptable-quality" images? What is the ratio of the max
> bandwidth attainable over USB vs bluetooth vs "traditional-monitor-
> connections".
>
> I cannot think of any other peripheral that isn't available in a USB
> version if not bluetooth. Do others have examples of they know? Just
> curious....
>
>

This monitor has a USB2.0 interface to drive the video display
(as well as the more ordinary and higher bandwidth interfaces).
It uses a compressed data stream, to compensate for the limitations
of USB2 bandwidth.

http://www.everythingusb.com/samsung...0ux_11970.html

You can also find display adapters, with USB on one end, and VGA
on the other end. The resolution options offered are not that
good, which is a limitation. Presumably one of those chips is
what is hiding inside the Samsung monitor.

Also, there is a subtle difference, between VGA, DVI, and USB. The
first two are being used to retransmit a full frame image, over
and over again. The USB is used to carry difference information
(repaint areas of the screen that have changed), because sending
the full frame over and over again, would make the screen impossibly
slow. As it is, USB devices like this, tend to offer a "slide show",
and you would notice the transmission method affecting your perception
of the experience.

Bluetooth is 3 megabits/sec max as far as I know. USB2.0 is 480 megabits/sec
theoretical, and somewhat less in practical usage.

http://en.wikipedia.org/wiki/Bluetooth
http://en.wikipedia.org/wiki/Usb

It wouldn't be fair or meaningful, to compare DVI to those two. But just
for kicks, a single link DVI uses three diff pairs RGB with data streams on them.
At a so-called 165MHz clock, each diff pair runs at 1650 megabits/sec, or
a total of 4950 megabits/sec. Dual link uses two instances of the interface,
for double that bandwidth (but dual link is not commonly used for your
average cheap LCD monitor). Just to offer some perspective with respect
to USB2.0.

http://en.wikipedia.org/wiki/Digital_Visual_Interface

Paul

"Rahul" <nospam@nospam.invalid> wrote in message
news:Xns9ADCCE2A53BF66650A1FC0D7811DDBC81@85.214.9 0.236...
> These days, every possible accessory seems to be "bluetooth" / USB
> interfaced. But I've never seen a "USB" monitor advertised. (neither
> bluetooth, of course) Neither CRT (who buys those!? :) ) nor LCD.
>
> Why is that? A bandwidth limitation? Or a need that doesn't exist? I doubt
> that is the reason since if I can want a USB headset why not a USB
> monitor?
>
> Besides there are "good" quality headsets available even on bluetooth. Is
> "acceptable-quality" sound transmission fundamentally a lower bandwidth
> process than "acceptable-quality" images? What is the ratio of the max
> bandwidth attainable over USB vs bluetooth vs "traditional-monitor-
> connections".
>
> I cannot think of any other peripheral that isn't available in a USB
> version if not bluetooth. Do others have examples of they know? Just
> curious....
>

It is perfect feasible to run a computer display via the USB interface (and
there are examples of this in practice). However, having said that, the USB
interface is far from an ideal choice for the job. The biggest limitations
are the limited bandwidth and that the host USB port (the one on the PC)
requires a considerable amount of CPU support when transmitting and
receiving data. Since this will be happening more or less continuously, the
CPU will have difficulty finding enough time for all the other activities
that it has to support. In general, it is most desireable to take as much
of the graphic functions away from the main CPU as possible. This is why
PCs have a dedicated Graphics Processor with its own dedicated interface
with the monitor. Then the CP can get on with doing what it does best.

"Shenan Stanley" <newshelper@gmail.com> wrote in news:uZEZDiu5IHA.1176
@TK2MSFTNGP02.phx.gbl:

>
> http://www.xbitlabs.com/articles/oth...g-sm940ux.html
> http://www.everythingusb.com/samsung...0ux_11970.html

Thanks Shenan! This is definately news to me. Very interesting, these USB-
monitors.

--
Rahul

"M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in
news:487d9e82$1_1@glkas0286.greenlnk.net:

>the CPU will have difficulty finding enough
> time for all the other activities that it has to support. In general,
> it is most desireable to take as much of the graphic functions away
> from the main CPU as possible.

Why specifically graphics? Let's say I'm watching a movie with a VGA-DVI
linked LCD screen but USB-linked speakers. The sound processing for USB
still falls onto the CPU. Is sound processing as a rule "cheaper" than
video?

>This is why PCs have a dedicated
> Graphics Processor with its own dedicated interface with the monitor.

They used to have "dedicated sound cards" too, I remember. I'm just curious
how those (and their "dedicated" interfaces) dissappeared much before the
VGA/DVI. Is sound processing fundamentally "easier" (or lower bandwidth)
than video or is it just an artifact of the specific way technology has
developed.


--
Rahul

Paul <nospam@needed.com> wrote in news:g5jl95$lc5$1@aioe.org:

> Bluetooth is 3 megabits/sec max as far as I know. USB2.0 is 480
> megabits/sec theoretical, and somewhat less in practical usage.
>

Thanks Paul. Does anyone know of scales that compare the bandwidth required
to get an "acceptable" human-perceived level of sound vs video. Again,
harps on my point of whether video *needs* a higher bandwidth channel than
sound.

Do my eyes capture at a higher bandwidth biologically than my ears? Only of
academic interest.

--
Rahul

Rahul <nospam@nospam.invalid> wrote:
> Is sound processing as a rule "cheaper" than video?

Yes. Remember the good old days when audio was stored on compact casettes
and also video was stored on VHS tapes? If I remember right the compact
audio tape casette was a lot smaller than a VHS video tape.

Today the physical size isn't such an obvious difference. A CD for music
has exactly the same size as a DVD which stores video. However, the CD and
the DVD are completely different media and if you compare those media when
it comes to storing data you will find that an audio CD usually stores
data equvalent to about 700 MB. A dual layer video DVD is capable to store
about 8 GB which is more than ten times as much as the audio CD.

The audio CD can contain up to 80 minutes of uncompressed sound sampled at
44.1 kHz with 16 bits per sample.

The DVD typically contains up to two hours of video and sound, but then
the video as well as the sound is heavily compressed with different mpeg
technologies.

If you use such compressions technologies on an audio CD you
can burn your music as mp3 files. Doing so you will find that you can
easily put ten times as much music on a single CD.

So in short, video takes about 100 times as much bandwidt as audio and
then we are still only looking at TV resolution which is something like
720x576 at 25 Hz. Today a 24 inch computer monitor has a typical
resolution of 1920x1200 pixels and is typically updated in 60 Hz. Compared
to the TV resolution this increases bandwidth with yet another factor of
about 10.

So when you compare your computer speakers with your computer
monitor you are comparing bandwidths which differ approximately 1000 times.

regards Henrik
--
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