[mythtv-users] Wierd recording problem on HDHR tuners

[David Engel]

On Wed, Nov 20, 2019 at 11:52:05AM -0600, 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?

Are you using an Nvidia Shield as your frontend or are you using an
Nvidia video card in your PC-based frontend?  This sounds very much
like the well known, mpeg2, decoding issue that plagues Nvidia devices
on some channels.  If that's the case, your only recourse is to
disable MediaCodec/VDPAU decoding and use software/ffmpeg decoding
instead.

David
-- 
David Engel
david at istwok.net