[mythtv-users] Strange Issue with Myth and HDHomeRun

[MythTV]

John,

A crazy thought based upon the comment about it only happening with  
the HDHR.

Could it be RF interference with the HDHR?  If the HDHR is next to a  
switch or other computing equipment they could be generating RF that  
interferes with reception. (The system running IPCop would explain  
why it only happens when the frontend is running.)

Also, a 100Mb network can become saturated with HD recording and  
LiveTV.  An OTA channel can have up to 19Mbps and a cable channel can  
be up to 38Mbps.  Now most broadcasts utilize a portion of that  
channel for each stream and I believe that the HDHR uses HW PID  
filtering so the entire transport stream is not sent.  If you do  
happen to get to the 19Mbps stream and you are recording and watching  
LiveTV your network would have to maintain a sustained 57Mbps.  Any  
additional burst traffic or significant packet loss could cause issues.

Run ifconfig from the terminal and it should show you the network  
stats including errors, dropped packets and overruns.

I have 2 HDHRs on a backend with 4 PVR-250s with 3 frontends all on a  
gigabit network and I haven't had any issues.

Just some thoughts, good luck.

Mino

On Feb 12, 2007, at 9:03 PM, John Welch wrote:

> Or maybe something with the HDD that the HDHR is streaming to? I'm
> not sure if bringing up the F/E would cause the B/E to hit the HDD at
> all. You may have been over it already but some hdparm -tT output on
> the B/E might be useful. Note that you could also try running hdparm -
> tT _while_ the HDHR is streaming to the HDD to see if you can trip it
> up. Do this test on the B/E local console to avoid influencing the
> network traffic.
>
> Good thought.  I hadn't really been focusing on the HDD at all.  My  
> only question there would be if it is a hard drive issue wouldn't I  
> see similar problems when I record from the PVR-150 or (especially)  
> the HD-3000?  Because I don't.  I've never seen any programs  
> recorded from the two tuner cards get corrupted, no matter what I  
> did on the F/E.  The one difference is that the HDHR is streaming  
> over the network, which is why I was looking toward the network.   
> I'll certainly do some hdparm tests though; it can't hurt that's  
> for sure.
>
> If you after you stop the F/E does the video return to normal? Have
> you tried running mythtvbackend with "-v all", start a recording, and
> then fire up the F/E to see if any messages are logged? If nothing
> else this might give you a good idea of what the F/E and B/E are
> doing together that could lead resource starvation of the HDHR.
>
> I've tried having the F/E running before a recording from the HDHR  
> starts, and in this case the recording gets corrupted right from  
> the get go.  I've also tried letting a recording go for a while and  
> then firing up the F/E in the middle of the recording.  In this  
> case the beginning of the recording is fine, but when I get to the  
> spot when I turned on the F/E it goes bad.  I've only done one  
> small test of what you suggest; turning off the F/E after a  
> recording started and the recording did go back to normal after the  
> F/E was off.  I haven't tried turning up the debugging on the back  
> end yet.  The funny thing is when the recording is going bad I  
> don't see anything special in the logs, but when the commercial  
> flagging processing the recording I get literally thousands and  
> thousands of messages in the log.  Here's just a real small sample:
> [mpeg2video @ 0x4dc9c4]invalid cbp at 73 10
> [mpeg2video @ 0x4dc9c4]Warning MVs not available
> [mpeg2video @ 0x4dc9c4]ac-tex damaged at 38 56
> [mpeg2video @ 0x4dc9c4]Warning MVs not available
> [mpeg2video @ 0x4dc9c4]current_picture not initalized
> 2007-02-12 18:33:36.669 AFD Error: Unknown decoding error
> [mpeg2video @ 0x4dc9c4]current_picture not initalized
> 2007-02-12 18:33:37.520 AFD Error: Unknown decoding error
> [mpeg2video @ 0x4dc9c4]mb incr damaged
> [mpeg2video @ 0x4dc9c4]Warning MVs not available
>
>
> Looking to the netowrk, with the HDHR the switch itself is usually
> the weak spot, as seen in the forums. Before helping diagnose network
> troubles a network diagram of switches, systems, and zones would be
> helpful.
>
> I must have just been typing my response to the first reply when  
> you posted this message.  See my last message for a description of  
> my network.
>
> Thanks for your help.
> John
>
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