[mythtv-users] HD-PVR strange behavior - solved!

[Michael T. Dean]

On 06/06/2019 12:10 AM, Will Dormann wrote:
> I've got a strangely-behaving HD-PVR 1212 where I haven't been able to
> pinpoint the problem (until just recently, and I'm sharing this story in
> case it helps anybody else here).  The symptoms are:  When I turn my A/V
> equipment (TV, HDMI Audio receiver) on or off, the HD-PVR stops recording.
...
> Just as I was about to give up and ask for advice here, I figured out
> the problem!
>
> My cable box (from Verizon FiOS) has both HDMI output going to the AV
> receiver *and* component output going to the HD-PVR.  The purpose here
> was in case I had the very-rare occasion where I'd want to bypass the
> entire MythTV system to see the output directly from the cable box. The
> symptoms I noticed were that if I turned on the AV equipment while an
> HD-PVR recording was going on, I'd notice the red light on the box go
> off for a couple seconds, and eventually recover.  The recordings were
> mostly OK, except for a drop-out around the time that the light went
> off.  In some cases, the corrupt video was enough to crash mythfrontend!
>
> Anyway, as a last resort I tried unplugging the HDMI cable from the
> cable box.  Bingo!  No amount of turning the receiver and/or TV on/off
> would interrupt the HD-PVR recording!
>
> Theory: When an interconnected HDMI device (TV or AV receiver) is power
> cycled, it sends some sort of signal

Sounds like HDMI CEC (Consumer Electronics Control) and your TV is 
sending a System Standby command.

See https://en.wikipedia.org/wiki/Consumer_Electronics_Control and 
https://www.howtogeek.com/207186/how-to-enable-hdmi-cec-on-your-tv-and-why-you-should/

Don't you love it when your devices are "smart" (read "smart enough to 
mess things up")?

Mike