Whats the point of Freeview?

Java Jive wrote:
I wouldn't attempt to broadcast HD on DTT. If they gave us lossless
SD, most of the motivation for HD would be removed.

Even the transmission of lossless SD (digitally) is a non starter.

--
Mark
Please replace invalid and invalid with gmx and net to reply.

Why?

On Mon, 20 Oct 2008 20:21:06 +0100, Mark Carver
wrote:

Java Jive wrote:
I wouldn't attempt to broadcast HD on DTT. If they gave us lossless
SD, most of the motivation for HD would be removed.

Even the transmission of lossless SD (digitally) is a non starter.

Java Jive wrote:
On Mon, 20 Oct 2008 20:21:06 +0100, Mark Carver
wrote:

Java Jive wrote:
I wouldn't attempt to broadcast HD on DTT. If they gave us lossless
SD, most of the motivation for HD would be removed.
Even the transmission of lossless SD (digitally) is a non starter.

Why?

Lossless SD requires 270 Mb/s. If you lump together the total available bit
rate of all 6 DTT muxes running at 64QAM you've only got 144 Mb/s, and that's
for one channel ?

Even at 48 Mb/s you'd only get three SD channels in. That's not beancounter
friendly !

I assume we're playing 'fantasy broadcasting' here ?

--
Mark
Please replace invalid and invalid with gmx and net to reply.

In article , Java Jive
wrote:
The definition of HiFi, though it was never actually
standardised as such, would have been a flat frequency response
between about 15-23,000Hz (and suitable SNR and THD),

A definition that wasn't standardised? What's one of those? I didn't
realise there was a definition of "hi-fi" with actual numbers in it
anyway. I thought it was just a verbal expression meaning "good
quality" that anybody could interpret according to their personal
preference.

Rod.
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I think you missed something?

On Mon, 20 Oct 2008 21:10:04 +0100, Roderick Stewart
wrote:

In article , Java Jive
wrote:

would have been
^^^^^^^^^^^^^^^^^^^^^^

A definition that wasn't standardised? What's one of those? I didn't
realise there was a definition of "hi-fi" with actual numbers in it
anyway.

Not if we used *all* the current analogue bandwidth after DSO?

On Mon, 20 Oct 2008 20:31:17 +0100, Mark Carver
wrote:

Lossless SD requires 270 Mb/s. If you lump together the total available bit
rate of all 6 DTT muxes running at 64QAM you've only got 144 Mb/s, and that's
for one channel ?

Mark Carver wrote:
Java Jive wrote:
On Mon, 20 Oct 2008 20:21:06 +0100, Mark Carver
wrote:

Java Jive wrote:
I wouldn't attempt to broadcast HD on DTT. If they gave us lossless
SD, most of the motivation for HD would be removed.
Even the transmission of lossless SD (digitally) is a non starter.

Why?

Lossless SD requires 270 Mb/s. If you lump together the total available
bit rate of all 6 DTT muxes running at 64QAM you've only got 144 Mb/s,
and that's for one channel ?

Even at 48 Mb/s you'd only get three SD channels in. That's not
beancounter friendly !

I assume we're playing 'fantasy broadcasting' here ?


Also, I doubt many people would notice the difference between a lossless
signal and one which is lossy and at a slightly lower bitrate.

Also remember that the average TV is probably setup really poorly or is
technically low quality (hence the huge difference in cost between a
domestic and a broadcast reference quality monitor).

And at the screen sizes and quality of equipment you might notice,
you'll start being more concerned with the lower resolution than what
compression is being used.

Java Jive wrote:
Why?


How about we look at it in the other direction? What sort of picture
could we fit in the available bandwidth?

Now these figure are going to be wrong for various reasons, but at least
give a vague idea of the concept.

Assume each pixel is RGB (not true, but easy) and is a single 8 bit byte
per pixel. That gives 3 bytes per pixel.

Now assume you want 16:9 widescreen. That means for a 16 x 9 pixel
screen you would have 144 pixels, which is 432 bytes so far.

They update at 25 frames per second, so we are now at 10800 bytes per
second.

Now we want to convert that to bits per second, so we assume each bit
can be mapped to one bit on the wire. So we are now at 86,400 bits per
second.

Assuming powers of a thousand (which is often the case for communication
links) that is 86.4kbits/sec.

We have 30Mbits/sec to use, so 30,000,000 bits/sec, so we can "fit"
about 350 of those little blocks in that space. That would be a grid of
about 20x20.

That equates to a screen resolution of 320 x 180.

A 2:1 lossless compression would give you 60Mbits/sec to play with,
which increases your resolution to 400 x 225

On Mon, 20 Oct 2008 21:10:04 +0100, Roderick Stewart wrote:

I didn't realise there was a definition of "hi-fi" with actual
numbers in it anyway.

Presumably DIN 45 500 (now replaced by EN 61 305) does have some actual
numbers in it related to frequency response and total harmonic distortion.

http://de.wikipedia.org/wiki/High_Fidelity

In article , J G Miller wrote:
I didn't realise there was a definition of "hi-fi" with actual
numbers in it anyway.

Presumably DIN 45 500 (now replaced by EN 61 305) does have some actual
numbers in it related to frequency response and total harmonic distortion.

http://de.wikipedia.org/wiki/High_Fidelity

Does this mean that anything failing to live up to this cannot be described
as "hi-fi"?

Rod.
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