[mythtv-users] Tuner cards that do HD?

Mon Apr 16 15:03:15 UTC 2007

Alex Malinovich wrote:
> On Mon, 2007-04-16 at 02:04 -0400, Mark Bobak wrote:
>> Rather than a tuner card, you might want to try an HDHomeRun.
>> http://www.silicondust.com/
>>
>> It's a standalone box, with two tuners and a network port.  It's fully
>> supported by Myth (as long as you use the 0.20-fixes branch).  Each
>> tuner supports OTA or cable tuning.  But, note that for cable tuning,
>> it will only tune unencrypted channels, which is going to be true for
>> any solution you come up with.
>>
>> The nice thing is, because they're a standalone device, you avoid the
>> whole kernel driver issue that you need to deal with when you're
>> running a tuner card.  I'm running two of them on my new Myth setup,
>> for a total of 4 tuners, strictly doing OTA in my case, and I'm happy
>> with them. 
> 
> Wow, looks like I'm behind the times here. So just to make sure I'm not
> missing anything here:
> 
> 1) I pay $169 to get the HDHomeRun
> 2) I plug in two coax cables and a network cord
> 3) I (somehow?) tell MythTV to use it
> 4) I watch TV?
> 
> Is it actually that easy? This looks like an awesome solution, I just
> want to make sure I'm not missing any important details before I dish
> out the $169. :)

There is one slightly difficult bit: Not in getting the hardware to 
work, but in matching it to your cable lineup (see below).
The hardware side is dead easy.

(Note that the HDHR gets its IP address solely by DHCP: you may have to 
turn on  the DHCP server in your router and give a DHCP range...this may 
also affect your wireless setup....)

If you have no idea what channels you might receive, you cannot yet 
really create a digital channel lineup on zap2it. But you have to at 
least create a digital listing, with some channels in it so that myth 
can find it when required.
Mythtv-setup has a tuner selection for the HDHR. You only need to know 
the unique ID of the box: it's printed on the bottom. It's like a MAC 
address. Create 2 tuners: HDHR-0 and HDHR-1.
Match each HDHR tuner with your digital source lineup on zap23it.
On one tuner, Quick Tuning set to Always (not 'Never') and ignoring 
encrypted channels,  do with a Full Scan, QAM256, us-cable and select 
whatever numbering style you like (that will get ignored).

You will get a largeish number of channels. If you look in the Channel 
Editor, the channels will show up as  74#3 etc. You can watch these with 
LiveTV.
WHAT they are is the difficult bit. Your cableco probably lists the 
channels by a virtual channel number: 125 or 402. Those numbers bear no 
relationship to the actual frequency the channel is transmitted on or 
the sub-channel (the __#3) or PID (serviceid in mythtv-language).

It helps to run a scan using the HDHR's own internal scanner, to get the 
frequency, real channel number and serviceid numbers. Note that that 
scan will include the encrypted channels and will likely be quite a 
large number of streams. (About 450 in total, for me).

Then you need to open a browser to the zap2it tv listings, and start 
watching LiveTV (really helps to have 2 computers!). When you find a 
match with the tv listing for the channel you are watching, use the 
Channel Editor (press 'E') and enter the real channel callsign or 
channel number (as reported by zap2it), then 'Probe'. Myth will query 
for and update the channel information and create the proper entries.

Unfortunately, there is no 'delete' option in the LiveTV Channel Editor 
and some streams (esp. FM audio feeds) can crash/hang your frontend. It 
is ESPECIALLY  useful if you run mythfrontend in a window at this point 
and call it from  one of a number of consoles so you can switch windows 
and kill the hung process.

You get rid of the unwatchable channels with mysql commanda or in the 
Channel Editor of mythtv-setup.
Now you can finalize your digital lineup at labs.zap2it.com. You know 
what you can actually receive and you can list the ones you want 
(ignoring promotional channels or video on demand or cartoons etc.)

If you already have a digital lineup and an HD card, just add the tuner 
and select the lineup...The hard work has already been done at some 
previous time.

If you already have a digital lineup, at least the universe of possible 
channels has been reduced.

There have been numerous posts about scanning failures in the recent 
past. Some of them are about actual scanning failures. Those seem to 
have been fixed in recent SVN changesets. But some posts complain that 
myth fails to properly define the channels it finds.
THAT is NOT a myth failure, nor a deficiency of the hardware. THAT 
arises because myth does not have nor can it possibly obtain the proper 
information it needs, just from the digital streams it receives.

Cablecos have a lot of freedom in how they broadcast channels on the 
wire. Channels which are simulcasts of local OTA channels are probably 
on the same channel (and sub-channel if digital). Otherwise the cableco 
can put any channel anywhere else in the spectrum and use any 
sub-channel it wants. Definitive channel information will not be 
transmitted with the digital stream. Partial information may be sent, 
but in a format intended solely for the cableco's own set top boxes.

So although myth can identify 'a' channel, at 74#3 it has NO knowledge 
about how that stream is identified at zap2it. It is up to the user to 
determine that the one originally called '74#3' is really described as 
125 by your cablco....and that 125 is xmltvid 10123, callsign WXYZ.

Once you tell myth that you want the channel tuned at 74#3 described as 
'Channel 125' and 'WXYZ' (as listed by zap2it) it knows how to pull down 
the listings for the channel, and to tune that channel when requested.

Now whether the mythfilldatabase listings actually match the tv 
listings, and whether you have actually discovered the correct channel 
are......unknown...

Geoff

-- 
              R. Geoffrey Newbury			
             newbury at mandamus.org

        Helping with the HTTP issue
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