[mythtvnz] Sky is renumbering its channels on 1-May-2013

[Stephen Worthington]

On Wed, 1 May 2013 11:40:18 +1200, you wrote:

>I've renumbered manually via mythweb but I've got the impression (maybe
>wrong) from this thread that its possible to use a DVB-S2 card, a card
>reader and a Sky card to receive Sky but without the sky box.
>
>I'd love to do this so that I don't suffer the degradation of the s-video
>link between the Sky STB and an analog video card.
>
>Is it possible? I don't have a problem with the subscription, I'd just
>like to get the quality I'm paying for!!

I agree entirely, the S-Video recordings I make from my Sky decoder
are twice the size of the DVB-S data it is receiving and suffer from
interference (50 Hz hum).  So I want to be able to record the real
DVB-S using my DVB-S2 cards, just as a MySky box does.  I do not want
all of the limitations of an actual MySky box (eg far too little
storage, having to swap between MySky and MythTV).

The short answer is: Yes, you can use sasc-ng to decode the encrypted
video.  Sasc-ng uses the dvbloopback driver to create new DVB-S tuners
that connect to the real DVB-S tuners but decrypt the encoded video
stream on the way through, using decryption keys from your Sky card
which it needs access to.

The long answer is: The setup is fairly complicated - it took me quite
a while to get it to work.  At present I have it set up with just one
Sky channel (Living Channel) for testing purposes, but now that I have
all the data I need from the process I went through to get the
renumbering data, I should now be able to automate the setup of all
the other Sky channels and move over to using sasc-ng full time.

The most fundamental problem is that it only works with some of the
Sky cards that they supply.  It does not work on the gold coloured
cards that come with MySky boxes, for example, and apparently with
some of the cards supplied with standard decoders.  The blue card I
have that came with my Pace decoder works fine, as apparently do all
suck cards.  I have put photos of it here so that you can compare it
to yours:

  http://www.jsw.gen.nz/mythtv/Blue_Sky_card_top.jpg
  http://www.jsw.gen.nz/mythtv/Blue_Sky_card_bottom.jpg

You need a card reader that can read the Sky card and provide access
to it for getting decryption keys.  My setup has an Openbox S10
satellite receiver as the card reader, which itself can record from
Sky to a USB 2 hard drive.  It has the option to set up a card server
that talks via TCP/IP in one of the protocols supported by sasc-ng.
Other card readers are ones such as the Phoenix one from a Jaycar kit
that needs an RS-232 port or commercially available USB ones.

The next complication is that apparently your Sky box has to update
its card every so often from data Sky broadcasts or it will stop
working.  Standard card readers do not do this updating, and I do not
think my S10 will either.  Apparently, this is needed at least every
month, so you need to put the card back in a real Sky box every so
often for up to one day for it to update.  I have not tested this yet,
as I have never run sasc-ng for longer than a few hours at a time.
There is one obvious way around this problem, which is to pay Sky for
a second decoder.  Then you will have two cards and can just swap the
cards between your sasc-ng card reader and one of the real Sky boxes
and always have one working card.  The downside of that is paying Sky
another $25? per month for an extra decoder.  Without two cards, you
would need to swap back to using S-Video from the real Sky decoder for
one day a month.  I think I have worked out how to do that, using a
script to update the videosource database to disable one source and
enable another, but I need to actually test it.  Having two decoders
would mean that you would legitimately be allowed to record from two
DVB-S2 cards at once though, without cheating on Sky.

The final complication is sasc-ng itself - you need exactly the right
version of it, set up exactly correctly, otherwise it does not work.
And it needs a patch done to the V4L code somewhere, which means you
need to compile V4L from source.  I have two DVB-S2 tuners, a TeVii
S470 PCIe card and a TBS 5922 USB one.  The S470 works with current
kernels, but the TBS card comes with V4L drivers to compile and
install to make it work, so I have just set up a batch file to add the
sasc-ng patch into their code before compiling, and that works fine
with both cards.  I have to do that again every time an updated kernel
is installed, and then recompile sasc-ng against the kernel.  But that
just means installing the new kernel, rebooting, running the two batch
files, and then rebooting again, so it is not really a problem.
Getting it set up was.

My other complication is that I need 100% communication with the S10
box, and the ethernet driver for my motherboard is flakey -
particularly under high traffic loads (when I am copying big files
from my Windows PC to the MythTV box, for example), it can just stop
working.  I have a Python script that pings my gigabit switch and
detects that it has stopped working, then reloads the driver and
restarts Samba and all is well again.  But that takes a number of
seconds at best, and new decryption keys are needed faster than that,
so sasc-ng would stop recording from Sky if that happened.  I am not
sure if it would recover, leaving me with just a hole in my recording,
or whether it would stop working completely.  So my current plan it to
use one of the spare slots in the MythTV box to add one of my old 100
Mbit PCI ethernet cards dedicated to talking to the S10 (which is only
100 Mbit/s anyway).

If you would like to attempt to set this up, then I would be happy to
help - I can provide the correct sasc-ng code, the patch and the batch
files and so on.