[mythtv-users] Wierd recording problem on HDHR tuners

Jay Foster jayf0ster at roadrunner.com
Wed Nov 20 19:47:41 UTC 2019


On 11/20/2019 9:52 AM, Kenneth Emerson wrote:
> I have 2 HDHR tuners: a quttro and a dual. All programming is OTA. All 
> recordings are perfect except for 1 channel (NBC). Watching recordings 
> from this channel breaks up for 1 second or less whenever there is a 
> large change in the picture like when the broadcast throws up an ID 
> banner for the news program. It's as if the stream is missing a type 
> 'A' frame so it pixelates until it gets the next A frame.
>
> So I have experimented as follows:
> Check signal with HDHR app: 100% for all three measurements
> use all the tuners (total of 6) -- all have the problem
> Connect a different antenna: same problem
> Disable commercial flagging: same problem
> Connect antenna to TV (live-no mythtv): perfect picture
> Use smart TV's software to connect directly to HDHR: perfect picture
>
> This tells me something is happening while reading/writing the stream 
> by the backend. I'm running v30 on Ubuntu 16.4. None of the other 
> channels exhibit this behavior. The problem is definitely in the 
> recording and not the playback.
>
> The recordings aren't unwatchable, just (very) annoying. I don't know 
> what else to try besides reinstalling everything including upgrading 
> to Ubuntu 18.04. Does anyone have any ideas less drastic?
>
> -- Ken Emerson
>
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It might not be the recording, but the playback.  Many NBC stations 
changed their MPEG2 encoding parameters a while back which results in a 
data stream that the Nvidia VDPAU driver/hardware does not handle well.  
If you are using VDPAU for playback, you might try switching to OpenGL 
or software decoding as a test to see if that makes a difference.  You 
could also try viewing the channel with vlc from the hdhomerun_gui 
application.
Jay
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