[mythtv-users] announce: script for locating QAM channels

[Brian Wood]

On Mar 4, 2006, at 11:08 PM, Mike wrote:

> Brian Wood wrote:
>> Interesting, and I'll give it a try.
>>
>> You say you have "signal strength" problems. "Unwatchably choppy"
>> might describe what I have seen when using the azap/mplayer method on
>> the 288 streams that atscscan found on my system.
>>
>> But the BER shows zero on all of these channels, so I don't think it
>> is a signal strength problem.
>>
>> What did your system show for BER ?? I wonder if you are having the
>> same problem I am. If I just run azap it shows "FE has lock" on every
>> line, but when I run mplayer to try and watch a stream I then see
>> many lines without the lock message, although a lot of them have it
>> also.
>>
>> Why would watching the stream affect the lock (if it really is). I
>> get a lot of breakup when using -nosound, and it gets even worse if I
>> try and use sound as well. I also get "too many packets in the
>> buffer" messages from mplayer.
>>
>> So I've had no real luck with QAM, with sumptoms similar to yours,
>> but I really don't think it is a signal strength problem.
>>
>> I have only one OTA atsc signal here, so if I can't get QAM signals I
>> have a pretty expensive off-air demod, especially since my TV has a
>> built-in atsc tuner.
>>
>> But I'll play with your script and see where it leads me, thanks.
>
> Just curious, but what motherboard do you have? (more specifically,  
> what
> south bridge chipset) I had a problem that sounds very similar to  
> yours
> where my tuner would lock on and off of the channel when I did  
> anything
> more than capture the stream. (like use mplayer to view it at the same
> time, or listen to music on the soundcard at the same time)
>

I have had the same symptoms with two different motherboards.  
Originally I tried this with a Via-based K8M8  board with an amd64  
3700 CPU, and I have since moved the card to a Dell machine with an  
Intel 82850-based board with a P4/2.4Ghz. Identical results on both  
machines.

Off-air reception of ATSC was perfect on the K8 system, I have not  
tried it on the P4.

Both these systems were running a 2.6.15 kernel.