This is never for inline references to parameters, only for starting parameter
documentation blocks. The "@p" command is for this, although unfortunately
Doxygen doesn't actually do anything with it and it's just an alias for code
text.
Graph::prep is a private function called initially from the main
process-callback before doing any work, and later at the end of
each process cycle. This sets up the process graph-chain and
process trigger queue.
Tempo information is irrelevant here.
This is required to collect relevent undo/redo information, notably
automation-data changes from Playlist::update_after_tempo_map_change and
DiskReader::playlist_ranges_moved.
The realtime thread should not move regions to begin with, and debug
builds woudl also assert since no undo operation was started.
MIDI clock start at the next beat (round_up_to_beat), so
here we have to round the current tick, rather than fall
back to a tick that is not yet complete, as 14da117bc8 does.
Reproduced with the Session from #9027
Start loop at bar 40 with MClk generator enabled.
```
#3 in __GI___assert_fail (assertion=0x7fedd86c4fd5 "clk_pos >= pos", file=0x7fedd86c38b7 "../libs/temporal/tempo.cc", line=3336, function=0x7fedd86c4f60 "void Temporal::TempoMap::midi_clock_beat_at_or_after(Temporal::samplepos_t, Temporal::samplepos_t&, uint32_t&) const") at assert.c:101
#4 in Temporal::TempoMap::midi_clock_beat_at_or_after(long, long&, unsigned int&) const (this= 0x560187e92c00, pos=20691033, clk_pos=@0x7fedc02178b8: 20691032, clk_beat=@0x7fedc02178c4: 11472) at ../libs/temporal/tempo.cc:3336
#5 in ARDOUR::MidiClockTicker::tick(long, long, unsigned int, long) (this=0x56018eed6db0, start_sample=20691033, end_sample=20692057, n_samples=1024, pre_roll=0) at ../libs/ardour/ticker.cc:170
#6 in ARDOUR::Session::send_mclk_for_cycle(long, long, unsigned int, long) (this=0x56018a216340, start_sample=20691033, end_sample=20692057, n_samples=1024, pre_roll=0) at ../libs/ardour/session.cc:7495
#7 in ARDOUR::AudioEngine::process_callback(unsigned int) (this=0x5601881a4f20, nframes=1024) at ../libs/ardour/audioengine.cc:563
```
This is the first step to fix various MIDI edit issues for sessions with
tempo-changes.
The old code, using .earlier returned an absolute position when
calculating a relative distance. This is only valid if the session has a
fixed tempo, and the origin is irrelevant when converting the timepos.
This resulted in follow up issues since there is a difference when
summing two positions (each with an origin) vs adding an offset to a
position.
Note: this API changes breaks compilation until the GUI is updated.
This fixes various rounding issues. Notably superclock to sample
conversion must always round down when playing forward.
`::process (start, end, speed = 1)` uses exclusive end.
Processing begins at `start` and end ends just before `end`.
Next cycle will begin with the current end.
One example where this failed:
- New session at 48kHz
- Change tempo to 130 BPM
- Enable snap to 1/8 note
- Snap playhead to 1|3|0
- Enable Metronome
- Play
`assert (superclock_to_samples ((*i).sclock(), sample_rate()) < end);`
end = 177231 samples == superclock 1042118280
A grid point is found at superclock 1042116920 (that is < 1042118280).
However converting it back to samples rounded it to sample 177231 == end,
while actual location is 1360 super-clock ticks before end.
The metronome click has to be started this cycle, since the same
position will not be found at the beginning of the next cycle, with
start = 177232.
Similarly a samplecnt_t t, converted to music-time and back must not be
later than the given sample.
```
timepos_t tsc (t);
assert (timepos_t::from_ticks (tsc.ticks ()).samples () <= t);
```
IOW. When playing forward, all super-clock time between 1|1|0 and 1|1|1
should round down to 1|1|0. "We have not yet reached the first tick".
This allows to export a session from the commandline tool
```Lua
AudioEngine:set_backend("None (Dummy)", "", "")
s = load_session ("/path/to/session", "snapshot")
assert (s);
e = s:simple_export()
assert (e:check_outputs ())
e:run_export ()
e = nil
```
This fixes an issue when destroying VST plugin UIs
rather than hiding them. Even though is hidden before destroying it,
the vistracker is also destroyed in the same function call, before
the event can be processed. The window state remains visible="1"
Music-time has a significantly reduced resolution.
When evaluating parameter automation using sample-time, different
samples can be mapped back to the same beat-tick. This can result in
endless loops.
The same automation event is found again:
```
start: 112640 next_event.when: b13334 -> dist a5892029@a662323200 in dist.samples: 1002
start: 113642 next_event.when: b13334 -> dist a269@a668214960 dist.samples: 0
```
Note this fix may not be correct, since time-domains are mixed.
"end" is using sample-time. Furthermore The loop is only entered
if there is an event found using timepos_t(start).
Further work will be required (ideally use the same resolution for
all time-domains, or force everything that is evaluated in RT-context
to a single time-domain)
