[mythtv-users] Silicon Dust HDHR5-4K

John P Poet jppoet at gmail.com
Sun Nov 8 18:30:47 UTC 2020

On Tue, Nov 3, 2020 at 6:59 PM Gary Buhrmaster <gary.buhrmaster at gmail.com>

> On Mon, Oct 26, 2020 at 6:17 PM John P Poet <jppoet at gmail.com> wrote:
> > Have you looked at Gary's ExternalRecorder for the HDHR?
> > https://github.com/garybuhrmaster/mythhdhrrecorder
> FD: I do not have, nor do I have any current
> plans to purchase, one of the new HDHR5-4K
> tuners for testing (and for that matter, my
> market does not currently have a transmitter
> (except by press release)) so any improvements
> will be based on guesses as to how to make
> things work better.
> While I believe that that recorder should be
> able to perform recording (although playback
> is still an issue), one will likely need to carefully
> configure the recorders and/or videosources
> and/or tuner priorities to achieve results you
> will find acceptable during testing.
> Some complexities (based on my current
> understanding, and not personal experience
>   - the HDHR5-4K has two ATSC 3.0/1.0
>     tuners, and two ATSC 1.0 (only) tuners
>   - In many markets the same (virtual)
>     channel is used for both 3.0 and 1.0
>     broadcasts from the same station.
>   - In most markets, not all channels are
>     both ATSC 3.0 *and* ATSC 1.0 that a
>     particular combo tuner may have
>     access to (some stations will be ATSC
>     1.0 only on the combo tuner).
>   - If a request for the new HTTP streaming
>     request is made to the tuner, and if the
>     (virtual) channel is available both 3.0
>     and 1.0, a 3.0 tuner will be chosen if
>     one is available (otherwise it will fall
>     back to a 1.0 tuner if a 1.0 tuner can
>     tune that (virtual) channel, but if the
>     virtual channel is 1.0 only, and no 1.0
>     tuners are free the device will use a
>     a ATSC 3.0/1.0 tuner).
> So, for the HDHR5-4K with mixed capabilities,
> and for applications such as MythTV, this
> can result in some artifacts that reportedly
> even SD is trying to think through (should
> there be a way to disable ATSC 3.0 selection
> so that the ATSC 1.0 versions show through
> (perhaps to allow apps that don't support
> AC-4 today to still operate?), should there
> be a way to make sure that the ATSC 3.0
> capable tuners are *only* used for ATSC 3.0
> channels if any exist in the market (so that
> they don't get used for an ATSC 1.0 channel
> that could be found on another tuner?),
> should ATSC 1.0 stations on a mixed
> capability tuner (that has any ATSC 3.0
> stations broadcasting?) have a priority
> lower than "normal" so that that tuner is
> selected only as a last resort for legacy
> stations, and lots of other possibilities).
> Right now there would appear to be no
> consensus as to what will work well for
> everyone (and having hundreds of knobs
> to adjust behavior is likely to just cause
> confusion and lots of holes in feet, and is
> in opposition to the "KISS" principle that
> most apps are targeting).
> With the latest external recorder version
> (and when I say latest, I mean as of today),
> the code has been modified such that
> combination tuners that have active ATSC
> 3.0 reception will be prioritized to be used
> first only for ATSC 3.0 channels, and the
> remaining ATSC 1.0 channels will be
> deprioritized such that the combo units
> will mostly be reserved for use by ATSC
> 3.0 channel requests, but can still
> fallback if there are not other tuners
> available for ATSC 1.0 channels.  This
> will not result in optimal results if one
> has multiple mixed-mode tuners (we
> need more control there), but it is
> probably good enough for initial testing.
> So, in some ideal world, converting all
> your OTA HDHR tuners to use the
> external recorder might mostly *just work*,
> but the reality is that we currently can't
> playback recordings with AC-4.
> So, ignoring that right now you can't
> play back any recording, what I would
> recommend for record only testing
> is to create two external recorders
> explicitly defining the combo tuner
> (and do not define the combo tuner
> to MythTV), and create them with
> a higher priority than your existing
> tuners, and create them with a videosource
> that only has the ATSC 3.0 channels
> that exist in your market defined.
> That will, essentially, "reserve" the
> tuner(s) for an ATSC 3.0 broadcast.
> Good luck.

For reference:

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