Current state of play with PVRs and DVD recorders?

On Thu, 11 Oct 2007 07:41:32 GMT, Bob Latham
wrote:

I have no idea if the Hummy has these problems I've not got one of those.

So your statement "I think this is very poor and I cannot think of any
other device so compromised" isn't based on any useful knowledge of
units on the market.

I am disappointed by this limitation as there is no way to make non
switched connections to a TV and to a DVD recorder and/or projector.

My Toppy feeds into my DVD recorder which chains into the TV just
fine.

For a
supposed premium product its very poor I cannot think of anything else so
limited. A Sky+ box is far better IMHO provided you already have a minimum
subscription.

If you like paying Sky, then fine. Not all of us do, and probably very
few people need the features you specified.
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In article ,
Bob Latham wrote:
In article ,
John wrote:

The HDRW720 went faulty recently and the insurance company provided a
Sony RDR-HXD870 DVD recorder. This has an analogue and a digital tuner,
a 160GB HDD, but no time-shift buffering. Sony's idea of pausing live
TV is, essentially, a "Record from now" button - absolutely bloody
rubbish.

Would you mind expanding on this please. Pausing live TV = "Record from
now" is exactly what I would expect, what did you expect? I presume you
can start watching again and continue with chasing playback?

What is time-shift buffering?

best guess Is you paragraph above talking about functions gained by
having the hard disc recording all of the time? Are you really complaining
about a lack of instant replay?

My Sky+ box can do this but I've switched it off to reduce the wear on the
hard disc and I don't find instant replay of any use, I'm not a football
fan.

This always makes me wonder ..the supposed 'wear'
on any HDD. It's just an assumption ..possibly
more belonging to the time when big tapes whipped
around in their air-cooled and conditioned cages...
I wonder just how much 'wear' really exists with an HDD?

Providing the HDD platters are turning constantly ..ie
are 'up to speed' and not consuming power (=heat) to get
to speed, then the only other thing that moves are the
almost mass-less armatures carrying the r/w heads.

These flick in and out continually, or else when
fractionally not in use, park waiting for the next
instruction.

Other than that, the r/w heads 'hover', as it were,
microns over the platten(ers), never actually coming
in direct physical contact with anything, other than
the molecules of air-stream created by the 5400/7200
passing draft of the platter surface...

So, apart from the motor, (or mag-drive), coming up
to speed - or magnetically braking when powered down
- there's little apart from the miniscule load on the
motor to 'wear out'.

Simply, if any of the component bits actually touch
each other, then the HDD and it's stored data is all
history in milliseconds flat!

Most HDDs, given the above, have a MTBF rate of at
least two years, with the more expensive rated at
a mean time before failure rate of 5 years. Most HDDs,
of course, will last many, many years longer than this.

The only HDDs that might just need continual powering
down when not in immediate use are probably the small
2.5" drives that are often found in laptop computers,
or other battery operated portable devices. The reason
for powering these HDDs 'up/down' is to save on battery
drain - not to save the drive.

(These smaller lighter drives are specifically designed
for this type of operation. There's a big difference
in the inherent 'inertial mass', if that's how it's
described, between a 2.5" drive and a standard 3.5").

...anyway ..just some background that I wonder if sometimes
that even the designers of PVRs, wrapped up as they are in
the tricky design of their project, may not always think
about.

It's possible that they place quite uneccessary HDD 'up/down'
power cycles into their software, putting a quite significant
strain on the mechanism that really just needn't be there.

(Perhaps the significant reason for the Technika PVR's HDD
failure that I had last week - it was continually 'up/down'
when there was absolutely no reason for it be so switched).

Just a thought.. ?)

Bill ZFC

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"Bob Latham" wrote in message
...
In article ,
John wrote:

The HDRW720 went faulty recently and the insurance company provided a
Sony RDR-HXD870 DVD recorder. This has an analogue and a digital tuner,
a 160GB HDD, but no time-shift buffering. Sony's idea of pausing live
TV is, essentially, a "Record from now" button - absolutely bloody
rubbish.

Would you mind expanding on this please. Pausing live TV = "Record from
now" is exactly what I would expect, what did you expect? I presume you
can start watching again and continue with chasing playback?

What is time-shift buffering?

best guess Is you paragraph above talking about functions gained by
having the hard disc recording all of the time? Are you really complaining
about a lack of instant replay?

Right, time shift buffering - your assumption is basically correct. Philips
implement it in such a way that you can think of it as a conveyor belt that
can hold up to 6 hours of live TV, so as an example, say I sit down to watch
TV at 6.00pm until midnight, the programmes go into the buffer (just a
section of the hard drive) so that I can pause the live stream if I need to.

It's a "rolling" 6 hour buffer, with the oldest programme "dropping off" the
end of the "conveyor belt" to make way for the latest stuff. If I just go to
bed at midnight and switch the recorder off, the buffer is flushed as the
machine is turned off.

However, if my brother rings me at 11.00pm and says that he has just got
home to find that his VCR didn't record that programme he wanted between
8.00 and 9.00pm, because that programme is in my time-shift buffer, I can
then "mark" it as a recording and it won't be flushed from the buffer. It
will then be a recording on the hard drive that I can then burn to DVD for
him.

Another example - suppose my wife's out for the evening and I'm 10 or 15
minutes into a programme and then think "oh crap, I should be recording this
for her", all I do is mark it in the buffer and it's done. Sony, Panasonic,
Pioneer and other DVD/Hard Drive recorders don't have the time shift buffer
so I would have missed the first part of the programme for her.

Because of the lack of a buffer on the Sony HXD870, when you pause live TV,
it sets off a true recording event that continues until you press the "Stop
Rec" button. You may only pause it for 3 minutes at 7.00pm, but if you
forget (or don't know) to press the Stop Rec button, it will record 5 hours
of TV to the hard drive before you turn the machine off at midnight. And
then you have to remember to delete it manually or your hard drive soon
fills up, it doesn't just get flushed out like a buffer does.

My Sky+ box can do this but I've switched it off to reduce the wear on the
hard disc

Hard drives don't fail easily. One of my 4 computers here is switched on and
off at least 6 times a day and it's still on it's original (5-year old) hard
drive. The Philips DVDR725H DVD/Hard drive recorder has been in daily use
for over 3 years and it's still perfect. I think you're cutting off your
nose to spite your face here because you're losing one of the main functions
of the Sky+ box.

and I don't find instant replay of any use, I'm not a football fan.

I hate football, but have you never watched anything and thought "what did
he say?" or "what happened then?" - being able to jump back 30 seconds or a
minute or whatever is brilliant.

John

Java Jive wrote:

There is a very sound logical justification for such a generalisation
- it's a generalisation! As a general principle, the average person
who doesn't know any better should always replace like with like, to
maximise the chances of the repair working. Accordingly, that is the
best general advice to give, and I make no apologies for giving it.

The average person that doesn't know any better should in general not be
making a repair. I credit the OP with more common sense than you
evidently do.

The advice that it might be a good idea to replace a desktop drive with
a laptop drive is not to be interpreted as "stick in any old laptop
drive and that'll do".

However, I've now checked up on the throughputs, and though my
recollection is basically correct, I hadn't realised there are still
quite so many older, slower IDE desktop drives about, so yes,
particularly in this case, I would agree that it would be best to
check the specs as well.

*Always* check the specifications.

Actual specifications for Data Transfer Rate of *every* IDE laptop
drive here is 100 MBps ...
....
So, as I hinted, depending on the specs of the original drive, you run
the risk of slowing down your machine by doing this.

Oh dear. The relevant rate to consider is not the interface rate but the
actual minimum, sustained data rate that can be written to the drive.
You should also note that an entire DVB-T *multiplex* doesn't exceed 32
Mbits/sec and so 100Mbytes/sec has plenty of spare head room and there
is no risk of 'slowing down' on those grounds.

In any case, as far as response times are concerned it is the *seek
times* that are relevant.

So, for the same price as this laptop drive, you can get a desktop
drive with 133% of its capacity and 333% of its life expectancy.

Do you know why a laptop drive MTBF is lower than a desktop drive?
Here's a clue - laptop drives are usually found in laptops.

If you start to take account of the full cost and environmental impact
of making hard drives, their use, and disposing of dead ones, perhaps
it's not such a good idea, financially, environmentally, or
performance-wise, to replace a desktop drive with a laptop drive.

Oh yes, your 'evidence' is overwhelming! That's why small form factor
drives are a thing of the past! No manufacturer would ever dream of
putting one in a PVR!

You got me. I fed the troll.

ESB

"Bob Latham" wrote in message
...
In article ,
John wrote:

"Bob Latham" wrote in message
...
In article ,
John wrote:

The HDRW720 went faulty recently and the insurance company provided a
Sony RDR-HXD870 DVD recorder. This has an analogue and a digital
tuner, a 160GB HDD, but no time-shift buffering. Sony's idea of
pausing live TV is, essentially, a "Record from now" button -
absolutely bloody rubbish.

Would you mind expanding on this please. Pausing live TV = "Record
from now" is exactly what I would expect, what did you expect? I
presume you can start watching again and continue with chasing
playback?

What is time-shift buffering?

best guess Is you paragraph above talking about functions gained by
having the hard disc recording all of the time? Are you really
complaining about a lack of instant replay?

[Snip explanation]

[Snip examples of usage]

I can see that you find this useful. Under unusual circumstances so would
I but they would be unusual.

Because of the lack of a buffer on the Sony HXD870, when you pause live
TV, it sets off a true recording event that continues until you press
the "Stop Rec" button. You may only pause it for 3 minutes at 7.00pm,
but if you forget (or don't know) to press the Stop Rec button, it will
record 5 hours of TV to the hard drive before you turn the machine off
at midnight.

Yes, I think my Sony does that.

And then you have to remember to delete it manually or
your hard drive soon fills up, it doesn't just get flushed out like a
buffer does.

Are you sure about this? I have a Sony RDR HXD910, it erases its "pause
live tv" buffer as soon as you've caught up or finish with it
automatically.

It (or at least my 870) doesn't have a "pause live TV buffer" to erase. Yes,
you can catch up with the live programme but the machine will still be
recording until you press the "stop rec" button, because it is a true
recording event.

Sony use the phrase "TV Pause" to actually mean "start recording now" and
yes, you can go to make a brew or whatever, then press "Play" and even catch
up with the live broadcast, but the machine will still continue to record
until you press "Stop Rec". That recording is then permanently on the hard
drive until you erase it.

Oh, and I wasn't having a go at you Bob. I just get infuriated that such a
useful function as the time shift buffer (that's been around for more than 3
years and is one of the major benefits of having a hard drive to record to
instead of tape) isn't implemented on machines rolling off the production
line today.

Technological progress means that things should get better, not have such a
basic and useful thing left out. My only experience with DVD/HDD recorders
has been with Philips and I just thought that all machines were the same in
this respect. I was *so* disappointed when I got the Sony that it didn't
incorporate a buffer. I was just glad that I didn't have to pay for it
myself )

John

On Thu, 11 Oct 2007 13:15:13 +0100, Ernst S Blofeld
wrote:

Java Jive wrote:

The average person that doesn't know any better should in general not be
making a repair.

How does the average person ever get to be any more than the average
person? By trying to do things for oneself! Generalisations such as
the one I gave are a useful guide in such a situation.

it is the *seek
times* that are relevant.

Since you mention them (items previously linked):

Laptop: Average Seek Time 12 ms
Desktop: Average Seek Time 8.9 ms

So, even by the criteria of your choice, the desktop drive still comes
out about 35% better.

You got me. I fed the troll.

If, as you appear clearly to, you think you're winning an argument,
then why risk any credibility that you think you've thereby achieved
by bothering to stoop to abuse?

In message , Bob Latham
wrote

Hang on here I'm not having a go, I'm just curious to understand why you
said your pause live tv was useless when to my mind it does exactly what
it says on the tin. What you wanted I think was instant playback.

Another reason for using a time shift buffer (on the hard disk) is skip
adverts. If you watch something that is, say, one hour old you can
easily skip through the adverts - until the real time end of the buffer
is reached.


--
Alan
news2006 {at} amac {dot} f2s {dot} com

In message , Ernst S Blofeld
wrote

Do you know why a laptop drive MTBF is lower than a desktop drive?
Here's a clue - laptop drives are usually found in laptops.


But not when they test them to establish the figures.

--
Alan
news2006 {at} amac {dot} f2s {dot} com