[mythtvnz] Hello from Newbie

[Stephen Worthington]

On Wed, 6 Nov 2013 15:53:34 -0800 (PST), you wrote:

>Hi,
>
>I am new to this but am intending to build a HTPC to run MythTV on Ubuntu 12.04LTS.
>I am currently in my research phase but have quite a few questions I would like to ask.
>Not sure of the correct etiquette but what I will do is outline what i am trying to achieve and then ask a couple of questions.
>
>I am currently using Sky HD for my TV and do not have a computer at home as I just use my work laptop.
>I want to get rid of sky and use a PC primarily to record and shift TV (must do HD). I am going to buy another PC to use for web-surfing, bit of Android development, project work, music, etc.
>
>I have a DVD Home theatre player and PS3 to play Blu-ray so really only interested in playing TV through HDMI to my
>Panasonic Vierra TV (supports full 1080p).  I have two aerials in my house
> an old UHF (never got a good picture on this) and currently use the satellite dish from Sky.
>
>
>So
>
>
>1. Which aerial should I use for HD recording DVB-T or DVB-S.

For the free-to-air channels, HD is available for TV One, TV2 and TV3
only, and only on DVB-T.  So you need to resurrect your UHF antenna
(or install a new one).  Ideally, to be able to record everything at
any time, you need three DVB-T tuners, one for each multiplex (TVNZ,
Mediaworks and Kordia).  But a lot of people seem to get by on just
two DVB-T tuners.  You can record from the +1 channels for TV One, TV2
and TV3 one hour later if you get a clash, but the +1 channels are SD
only.  You do need a good enough antenna that ensures a signal that
can be split into at least 3 or 4 different feeds - one for the TV
directly, and the others to each of your DVB-T tuners.

If you want to digitally record from Sky still, but using MythTV, then
I do have that working, but not perfectly - I still get bad Sky
recordings when I record too much at once, and occasionally just for
no reason at all.  So I do some manual fiddling with my recording
schedules to make sure I record Sky programs in the middle of the
night when nothing else is recording.  The setup I use has two DVB-S2
tuners and it decrypts the Sky data using the Sky card from my Pace
STB put in a card reader that makes it accessible to MythTV via some
special software.  This process does not work unless Sky has given you
the right sort of card - the ones in MySky boxes probably will not
work.

Sky also broadcasts some HD channels, but you have to pay them for an
"HD ticket".  I do not pay the extra, so I have not tried recording HD
from Sky.

>2. I am thinking of running front-end and back end on one computer in my living room dedicated to TV. Is this a good option and can I keep this quiet enough.

Yes.  My setup and my mother's are like that and I find that I do not
notice the noise from the PC when watching TV.  However, both of those
boxes use silent Nvidia video cards (big heat sinks instead of fans).
Silent video cards usually take two slots as the heat sink has to be
quite big to cope with the heat output of the card.  Video card fans
tend to be quite small and hence quite noisy.  PC builds with recent
hardware tend to be pretty quiet except for the video card fan.  There
are good low noise power supplies and cases, and both AMD and Intel
CPUs are normally provided with decently quiet fans now.

>3. Can I post a hardware spec for advice on whether this set-up will cope with both front-end and back-end for my requirements,

The basic need for the frontend box or combined backend/frontend box
is to be able to play HD H.264 (1080p, 1080i and 720p) video
perfectly.  There are now several options that can do that.

Firstly, the traditional MythTV way is to use an Nvidia video card
with a high enough specification that it can do all the hard work in
the GPU, using the Linux VDPAU API calls.  I use an Nvidia GT 220
based card (now obsolete).  The card needs to do the full deinterlace
(Temporal 2x in MythTV terms).  So a bottom end card does not work.
When I got my GT 220 card, the GT 210 was much cheaper, but not up to
the job.  I have not looked at the specs for the current Nvidia cards,
but if you download the Nvidia drivers, there is usually a full set of
documentation in the download that says somewhere in it what each chip
is capable of.  On my MythTV box with Nvidia V304 drivers, it is here:

  R:/usr/share/doc/nvidia-304-updates/html/supportedchips.html

Look for a card that is listed as doing VDPAU features at C or
preferably D level.  It also needs to have sufficient shaders - but I
am not sure just how many and how good they have to be.  There used to
be a need for at least 512 Mbytes of video RAM on the card also, but I
am not sure if that still applies.  In any case, most cards have more
than that now.

The second way to do it is to have a powerful enough CPU that it can
do it all by itself, no matter what the video card is.  The AMD
FX-8150 (quad core) in my current MythTV box seems to be able to do
that, as does the Intel Core i7-3610QM (quad core with hyperthreading
= 8 core) in my laptop.  But that involves running the CPU quite hard
on more than two cores - I found setting the MythTV video settings to
use only 1 or 2 cores did not work properly.  So it makes the box hot
and also use more electricity.  As a result, I still prefer to use a
good Nvidia card.

The third option is to use the VAAPI interface in the latest Intel
drivers, and use an Intel processor with a recent HD 4000 video
builtin.  My laptop can do that, but the standard Intel drivers that
get installed with a lot of Linux distributions are not up to the job
and I had to install the latest from the 01.org web site.  And since
then, the 01.org web site has removed support for my Mythbuntu 12.04
setup - you would need to install Ubuntu 13.10 to get 01.org to work,
and that is not a supported MythTV setup.  So I regard the Intel VAAPI
option as a bit experimental still, but worth trying if you already
have the right hardware (such as an existing laptop).

Very experimental, but reported to work, is to use some recent ATI
Radeon video cards and VAAPI or VDPAU with the latest ATI drivers. ATI
drivers on Linux tend to be even buggier than the Windows ATI drivers,
so this option is not yet really worth considering yet.

Since this is a PC that will likely be on for a fair part of the day,
or even 24/7, it pays to buy better quality parts that will run at low
power when not being fully used.  So the latest generation CPUs and
motherboards are recommended - I just updated my 5 year old Windows PC
from a dual core Intel to an 8 core AMD at nearly twice the CPU clock
speed and four times the RAM, and the power used in normal work went
down from 140-150 W to around 130 W.

And get a good power supply - at least an 80 Plus Bronze rated one,
and preferably an 80 Plus Gold rated one.  That keeps the power supply
efficiency above 80% even when the box is idle, and usually ensures a
power supply that is not going to just stop working a week after the
warranty runs out.  The 80 Plus Gold one I just bought (to replace one
that died) actually has a 5 year warranty.  Cheap power supplies are
not worth it - a high efficiency one will likely pay for itself in
reduced electricity costs in about two years.

It is also worth considering how you are going to use your MythTV box.
Some people just record a few programmes, watch them and then delete
them.  For those people, a setup with two hard drives is just fine,
and even just one drive might be OK.  But I turned out to be the sort
that records lots of things I feel I might want to watch, and never
wants to delete them - so I have wound up with over 12 Tbytes of
recordings on five drives now.  With a Sky box you have no option to
just add more storage, but with MythTV if you turn out to be like me,
it pays to have planned ahead and got a motherboard with lots of SATA
ports and a case that is large enough to hold lots of drives.  Another
consideration is if you are going to load all your DVDs and CDs onto
the box as well as having it do TV recording - that also uses up lots
of disk space.

>Thanks,
>
> 
>Alex Marshall
>Mob: 027 444 0759