[mythtv-users] pcHDTV 5500 must be set as Analog V4L, hiss, boo

Jim Carter jimc at math.ucla.edu
Tue Jul 17 19:53:49 UTC 2007


On Mon, 16 Jul 2007, Michael Basus wrote:

> I'm trying to set up my 5500 for analog cable only and have hit a similar 
> brick wall.
> 
> I can get V4L working perfectly on my box--I can watch live tv and schedule 
> recordings--but if I switch in and out of "Watch TV" mode, the backend will 
> crash, sometimes taking the frontend down with it.  This isn't really 
> acceptable for media center use when someone might accidentally go to the 
> MythTV menu and want to jump right back live TV.

That's nasty.  But I can't offer any insights -- I've never had the backend 
crash.  However, when I was messing around with kdetv and with fbtv, I 
noticed that when I tuned to a channel with no signal, or possibly they 
had signals but not NTSC, those programs would eventually crash.  I 
interpreted it as the codec not being sufficiently garbage-proof, and dealt 
with the issue by Not Doing That.

(I have never yet found a HD signal on this basic cable, but that doesn't 
mean it's not there...  Or maybe even the free channels are encrypted; 
some providers do that.)

> Using DVB, when I set up just the "Television" input source, it doesn't 
> work.  When I go to Watch TV, I can change channels but all I get is a black 
> screen on all of them.  On the bottom of the screen is a message about 
> signal strength, which might mean that it's trying to use the DVB input 
> device to get Television channels, which of course won't work.  This is 
> despite the fact that MythTV has the DVB device set to "(None)".

I had the same behavior.  I interpreted it as trying and failing to lock on 
to the (nonexistent) QAM-256 channel at that frequency.  I also searched 
for QAM-64 and 8VSB, with no hits.

> I've gotten DVB drivers to work by setting up two input sources for the 
> card.  I set up the "Television" input source as normal, and set up the 
> "DVB" input source with some dummy data--in this case, the same analog cable 
> data as the "Television" source.  When I start live tv, it starts on the 
> blank DVB input source, but then I hit "C" and it switches to the Television 
> source and all is well--until I try to schedule a recording.  Every 
> recording I schedule has a "Recorder Failed" error that looks like this in 
> the log:

OK, you got farther than I did -- setting up the card as DVB, I never saw 
anything on the analog source.  I'll give it a try and see if, for me, it 
also bogusly tries to set up the DVB tuner.  You are using version 0.20 of 
MythTV, aren't you?  That's my version.

Hmm, if you select a show from the guide and tell the backend to record it, 
my understanding is that the backend is smart enough to pick the "best" 
data source, i.e. DVB.  Perhaps if the guide data attached to the DVB 
section lacked the show you wanted to record, the backend would pick the 
analog section and succeed.  Now, how do you create an empty or irrelevant 
programming source?  I used "none"; I'm assuming that my choice was 
ineffective.

> Back to your message, are you saying you got V4L to work without any hitches 
> on your 5500?  If that's the case I can look to updating drivers or a 
> reinstall to remedy my problems, and just use V4L since analog cable is all 
> I have.  

Right, as far as I can see there is no fault with the card or drivers if 
you use V4L (analog only).  There have been issues between keyboard and 
chair, and the machine is seriously underpowered (Pentium III "Coppermine" 
at 1.0 GHz, 256 Mb RAM,  40 Gb disc) but is just barely able to do a proof 
of concept before I blow away MCE and migrate to the new machine.


James F. Carter          Voice 310 825 2897    FAX 310 206 6673
UCLA-Mathnet;  6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA 90095-1555
Email: jimc at math.ucla.edu  http://www.math.ucla.edu/~jimc (q.v. for PGP key)


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