[mythtv-users] A General Directions Question

Dewey Smolka dsmolka at gmail.com
Sat Jul 5 22:36:33 UTC 2008

Just wanted to clarify a few points.

On Thu, Jul 3, 2008 at 9:15 AM, Fred Squires <fsquires at gmail.com> wrote:
> On Thu, Jul 3, 2008 at 8:28 AM, NoName Anonymous <iwmdil at yahoo.com> wrote:
>> Actually, I haven't thought much about HD.  My TV is capable of it (HD) and
>> the day will come, but right now I'm worried about the Analog to Digital
>> switch.  To me, the HD switch is just a bandwidth and processing problem.  I
>> don't mind waiting a bit for MythTV HD code to get out of alpha, and won't
>> mind playing a bit with a beta.

Playing HD (via unencrypted MPEG or H264 streams) in Myth is solid and
stable, provided you have capable hardware. Capturing unencrypted
digital HD in Myth is also stable and solid with, e.g. the HDHomerun
or PCHDTV cards. Capuring digital HD over firewire is also supported
but the anecdotal evidence suggests that this is a trickier way to do
it, and the availability of channels varies widely depending on area
and provider.

The only Myth code around HD that is still alpha, though by all
reports developing rapidly, is the driver and support for the new
Hauppage HDPVR device, which relies on an external satellite or cable
STB. It is able to capture and encode analog HD signals from the
component outputs of the STBs.

> Right now with comcast you don't really need to worry about the Analog
> to Digital switch, they've announced that they're going to make the
> switch in 2010, but if enough people complain who knows if it will
> happen that soon.

Depending on where you live, you may not need to worry about it just
yet, you may need to start worrying about it right now, or it may be
too late. In Chicago, for example, pretty much all of what used to be
'basic cable' has been digital for the last two years, both with
Comcast and with RCN.

>> The big question then becomes whether the digital signal is
>> encrypted or not.  It it's encrypted then every TV (or PVR) would require
>> it's own STB and internal TV tuners would become worthless.

Internal TV tuners become useless. But not every PVR per se needs its
own STB. Every input you want to be able to record/watch
simultaneously needs its own STB to get channels from a cable or
satellite provider. If you want to record two Directv feeds at a time
(or record one and watch one live) you'll need two STBs. But you can
have two STBs with a single Myth BE/FE combo, or two STBs feeding a
single BE that in turn feeds as many FEs as your network can support.
The number of STBs you need is a function of how many channels you
want simultaneously, not of how many Myth systems you want to run or
to how many TVs.

> The FCC requires that cable companys provide a set top box with an
> active Firewire port to any HD subscribers that request it.  The only
> problem is that it's not required to output anything unencrypted
> (except possibly local OTA stations), so you might or might not get
> anything useful with it.

They are required to broadcast OTA stations in the clear. But they are
not required to give you access to any other digital or HD stations.

> One advantage of firewire is that it can be
> used to record from and also to change channels, so even if it doesn't
> output anything useful you can use it to change channels more reliably
> than with an ir blaster.

The most reliable way to change channels is through direct control via
the serial port. Unfortunately there are not many STBs that have low
speed data ports at all, or have the ports enabled. I was never able
to get a serial-controllable box from Comcast, though the standard
Directv boxes do have this ability, and it's very easy to get working.

>>      +  DirecTV is via an HDPVR (wanting a second) and I don't understand
>> how the signal gets to MythTV (or if it does at all).  What viable options
>> might exist to get DirecTV signals to a MythTV box (Generic PVR)?

1) Analog output (best is S-video) with aux audio output to a HW
encoding card like the Hauppage PVR series; control via serial->null
modem adapter->9-pin serial-USB cable.

2) Analog output (best is S-video) with aux audio output to a HW
encoding card like the Hauppage PVR series; control via IR blaster.

3) Analog output (best is S-video) with aux audio output to a
framegrabber card; same control options.

4) With the HD recievers, components outs to HDPVR (still
expirimental); not sure about contol options.

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