[mythtv-users] Tuner cards that do HD?
R. G. Newbury
newbury at mandamus.org
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
<a href="http://www.w3.org/Protocols/">HTTP</a>
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