[mythtv-users] ATSC 3.0 HDHR Quatro

David Engel david at istwok.net
Thu Apr 23 02:34:32 UTC 2020


On Wed, Apr 22, 2020 at 12:56:01PM -0700, Nick Kelsey wrote:
> 
> >> Not sure if Mythtv could be made to support it but it's interesting.
> >
> > I would expect the internal support should be possible.
> > It is even possible it will all just work out of the box.
> >
> > The 3rd party external recorder supporting HDHR
> > tuners also might just work without changes since the
> > new tuner will be using the same HTTP streaming
> > protocols as previous devices.

My expectation is that both internal and external [MythTV] recorders
would not need much to get them working.

> > But in any case until the device(s) ship no one will
> > have one to test and develop with so it is mostly
> > theoretical at this point.
> >
> > If someone really wants early support one might ask
> > on the developers mail list if a developer living in one
> > of the early cities for ATSC 3.0 would prioritize such
> > work in exchange for a free (to them) device for their
> > work and then purchase one for you and one for them
> > (or alternatively be prepared to write the patches
> > yourself as needed).  There are only a few devs who
> > have historically tended to the tuner/recorder codes.
> > I don't know the overlap between the experienced
> > devs and their locations for early ATSC 3.0 channels.

I live in one of the early cites and would be willing to do the work
as long as it doesn't have to start right away.  I'm too overwhelmed
with other things to do much of any MythTV work right now but should
free up in a month or two.

> > It should be noted that the upstream hdhomerun
> > library had initial updates for the new devices back
> > in early March.  I doubt most distros have updated to
> > that newer version of the library, and more updates
> > may be necessary, so the project may end up being
> > forced to bundle the library again for a time (as I
> > recall, the change was to recognize the new tuner
> > type as being a valid tuner, but I only skim commit
> > logs so there may be more).
> 
> The HDHomeRun remuxes the video to MPEG-TS to make it easy to work with -
> mythtv should be able to record it like ATSC/DVB.
> 
> The DEV version support saving and replaying pcap files so a developer who
> isn't in a region with a ATSC 3.0 broadcast can replay a capture from
> someone who does have a local broadcast.
> 
> It should work with an older version of libhdhomerun. The atsc3 patch fixes
> the logic that recommends what color to use when displaying the signal level
> (ie green because the signal strength is good).
> 
> Tuning needs to be by virtual channel number or by frequency-program (ie
> SPTS).

I have two main concerns.  Everything else is hopefully straight
forward.

The first concern is handling channel scanning.  Does the new HDHR
work similarly to the older, ATSC 1 ones, just with new modulation(s)?

The second concern is the scheduling.  As I understand it, there are
two, ATSC 3 tuners and two, ATSC 1 tuners.  The simplest thing to do
would be to treat it as two, independent, 2-tuner devices, one which
does only ATSC 3 and the other only ATSC 1.  The complexity comes in
if the ATSC 3 tuners can fall back to ATSC 1 or virtual channel
numbers are shared between ATSC 3 and 1.

David

> Video is HEVC. Figure 4k content needs HEVC support in the GPU.
> 
> Audio can be AC4 - there is a ffmpeg fork with AC4 support.
> 
> Interactive content (HTML/JS apps) is complex but not required to watch TV.
> 
> Nick
> 
> 
> 
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-- 
David Engel
david at istwok.net


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