[mythtv-users] HDHomeRun tuners and network switches

[Peter Bennett]

On 1/20/22 8:51 AM, James Abernathy wrote:
> I'm trying to fix some issues with mythtv having breakups in the 
> signal that could be a number of things like antenna placement, 
> original signal quality, or networking issues.
>
> My production mythtv backend is using a WinTV quadHD PCI3 tuner card 
> and I generally don't have issues with those recordings.  It's always 
> the HDHomerun tuners that are connected to a test backend.
>
> I watch either backend using FireTV 4K sticks or Nvidia Shield TV with 
> the mythfrontend and Leanfront apps. So lots of networking potential 
> problem areas.  All of the streaming devices and backends are wired 
> with either CAT5e or CAT 6 cables.
>
> I have at the top of the tree a TP Link AX50 WiFi 6 AP/router.  Each 
> of the ports are connected to 8-port GbE switches in other cabinets or 
> rooms.
>
> The problem got bad enough this morning that I decided to dig deeper 
> into the situation.  While watching the recorded morning news, the 
> picture kept pixelating with lost sound a lot more than is tolerable.  
> I checked the HDHR tuner with their signal app and the quality and 
> stability of the signal looked great.
>
> The Shield TV and mythtv test backend that was recording the program 
> are on the same switch 1 in a cabinet and the HDHR tuner was connected 
> to another switch in another cabinet.  So I moved the cables around so 
> that one of the GbE switches had the HDHR, mythtv backend, and the 
> cable running to the cabinet with a switch for the streaming devices. 
> This seems to fix the issue.  However if the cable going to the 
> streaming devices is plugged into the switch above then I have issues. 
> An attempt at a schematic below to make it clearer.
>
> AP-router-----> switch 1 in closet (test mythtv-backend, HDHR tuner)
>                |-----> switch 2 in closet
>                |-----> switch 3 in cabinet with streaming devices 
> (FireTV, Shield)
>
> The above has the most break ups when watching
>
> However, moving the cable leading to switch 3 from the AP/router to 
> switch 1 seems to work best.
>
> Does this make sense or point to a problem?
>
> Jim A
>
>
I had this problem a few years back with the HD Homerun Prime. 
Pixellation every minute or so. After lots of messing around it turned 
out that if the signal from the HDHomerun Prime to the backend traveled 
through the router, sometimes a UDP message was dropped. I forget the 
router brand. Reconfiguring the network so that the signal only traveled 
through a switch solved it. It looks like this does not happen in your 
case, maybe the switch between the hd homerun and the backend is the 
problem.

I verified it with this test, from the manual for the hd homerun prime, 
see below. When the signal passed through the router, occasional errors 
were reported in the dots. Without the router between there were no errors.

*Saving a stream:**
*
The hdhomerun_config command can be used to automate the process of 
saving to the local
filesystem:
format: hdhomerun_config <id> save /tuner<n> <filename>
eg:     hdhomerun_config FFFFFFFF save /tuner0 capture.ts
While saving the stream, a single period “.” will be displayed every 
second. Additionally, as of the
20080609 release, the hdhomerun_config will detect reception and network 
errors, replacing the
“.” with an alternative character to indicate the problem.
Example output:
............n...............................n..........ts..........
-- Video statistics --
23323 packets recieved, 2 network errors, 1 transport errors, 1 sequence 
errors

*Advanced:* A filename of “null” indicates no file should be created, 
allowing the use of the save
command as a diagnostic tool.

Peter



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