Drive the HDHomeRun directly and record ourselves; drop Tvheadend

Airwaves had outgrown Tvheadend: it owned the lineup, guide, recording
rules and signal history, and used Tvheadend only to tune the HDHomeRun
as a dumb pipe and write files, through a second source of truth kept in
step every minute. Tvheadend's over-the-air guide grabber also held a
tuner for minutes at a time for listings nothing used.

airwavesd now uses the device natively. The lineup is the HDHomeRun's
own scan (lineup.json with frequencies and programs), and Scan for
channels in Reception scans again. A tuner manager (internal/tuner) is
the device's only client: each RF channel in use is streamed once and
every viewer, recording and HDHomeRun client gets its own program from
it, so watching 9.2 while 9.1 records takes one tuner. With every tuner
taken, a recording takes one from a viewer, a viewer one from Measure
now, and a viewer changing channels gets their own tuner back; a tuner
lingers on its RF channel for a moment so coming back is instant.
Signal readings are the device's strength, quality and symbol quality,
with errors counted in what actually arrived.

Recording is Airwaves' own: files in the recordings folder, a folder per
show, described in dvr.json with the rules. Coming up says which airings
won't get a tuner and why. A recording under way can be watched from
the start, extended, or stopped keeping what it has; losing the tuner or
signal makes a gap rather than an end, a restart carries on, and a
finished recording says what it's missing. Playback reads the files
directly, so it seeks. A corrupt dvr.json is set aside instead of
stopping the server.

Gone with Tvheadend: its container, the demo channels, the USB tuner
overlay and dB/BER readings no tuner here had, and the app's "needs
another tuner" notes for ATSC 3.0.

commit

e13385562eec65051385ecf4d432559ee507c389

parent

e3bf70d34ac5793b1e1c7a20632b70f6203d73d5

author

FelineStateMachine <226808055+FelineStateMachine@users.noreply.github.com>

kind

feat risk score 3.0 of 3, Jev's estimate