"Mark Carver" <mark.carver@invalid.invalid> wrote in message
news:irnqdsFkfh8U1@mid.individual.net...
> On 30/09/2021 21:20, NY wrote:
>> Going off at a tangent slightly, but I've always wondered? How large are
>> the playout files, compared with the roughly 1-3 GB/hour that is received
>> on Freeview after it has been compressed to within an inch of its life?
>
> They are AS-11 files, Rule of thumb I think is about 1GB per minute. As
> for transferring time etc, well, do the maths

Hmm. So they are roughly 50x the size of the SD file that the viewer
receives. That's a hell of a lot of compression and information thrown away
during multiplexing.

"Indy Jess John" <bathwatchdog@OMITTHISgooglemail.com> wrote in message
news:sj5dml$ooc$1@dont-email.me...
> On 30/09/2021 21:20, NY wrote:
>
>> As a colleague used to say, "Never
>> underestimate the baud rate of an artic full of mag tapes".
>>
> I was once asked to drive 170 miles with 2 reels of mag tapes in my car as
> the only practical way of getting that much data to its destination in
> time to meet a processing deadline.
>
> Of course, having delivered it, I had to drive the 170 miles back to where
> I normally worked. That was a tiring day!

That brings back memories of working at a customer site in rural Ireland in
the mid 1990s. We'd driven down from Dublin the night before and were about
to start work installing the new package that I was responsible for on the
server. But we discovered a show-stopping error in someone else's software.
The guy who "owned" it was only too pleased to give up his Saturday to work
on the modification, but he then needed to get it to us. We only had a slow
9600 baud modem connection for some reason (*). We did the maths and worked
out that it was *slightly* faster for us to wait for it to transfer, than it
was to drive to Dublin where it could be sent a lot more quickly, and then
return with the file on CD or QIC tape - but there was not much in it.

Fast-forward to a few years ago and we have a similar situation, scaled up.
We were living temporarily at a cottage with a very slow internet
connection - I think it was about 0.8 Mbps down and 0.3 Mbps up. I needed to
update the maps on my wife's satnav in her car. And that meant a download of
about 4 GB. That was a real "overnight and most of the next day" job :-(
4000*8/0.8 = 11 hours (approx).

The "truckload of tapes" comment was made at a time when we used big 12"
reels of tape, not QIC cartridges or 8 mm DAT tape. They were big and
heavy - and woe betide anyone who dropped a tape, because the end of the
tape would invariably unwind itself all over the floor, and the spool may
even shatter.

(*) I think the office had an internal 10/100 Mbps LAN which had no
connection to the outside world.

In article <sj6hkj$j6c$1@dont-email.me>, NY <me@privacy.invalid> wrote:

> Hmm. So they are roughly 50x the size of the SD file that the viewer
> receives. That's a hell of a lot of compression and information thrown
> away during multiplexing.

Lot of compression, but not as clear about how much information is
discarded.

JIm

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