This note-mode had no effect on anything at all, at least as far back
as 5.12. There is a note-mode in the GUI which affects the duration of notes
added using the GUI, and that remains in place. It is not clear
if the _percussive member of Evoral::Sequence ever had any effect on
the actual MIDI event stream the Sequence could generate.
Code within the method was using @param start_time rather than start, which is a modified
value required to generate the correct results.
This comment also contains some logical reordering, optimization and commenting
on this rather complex method.
Note that the value is still defined in Beats (ticks) rather than seconds
which means that the interpolation density is tempo-dependent. This
should still likely change one day.
Region-gain (unlike other automation) is specific to the
region and independent of the source. Region::start() offset
does not apply. When region-start is trimmed the region's
envelope is modified (not just offset). The event-list is truncated.
Any audio-region envelope does (and must) have a point exactly
at the start and end of the region.
truncate_start() can thus calculate the earliest position of
valid events with the new length relative to the last event.
The mathematical operator for that is subtraction, not distance.
we screen midi files for some aggregate info:
used channels, used patches, and note-count
you can't do this from open() because there are cases (after importing)
when the source exists but it is not yet written to disk
Files that have many tracks, each with tempo information
were near impossible to load (30+ mins on modern 4.2Ghz CPU!),
because tempo is parsed incrementally:
```
For each new track:
for each new tempo-event:
rewind()
for each loaded track so far:
for each event on this track so far
```
This reduces the complexity from O(tracks^2 * tempos^2)
to O(tracks * tempos).
"Come Thou Fount Tempo Map.mid" has 238 Tracks and 56168 total
Tempo Changes (236 per track). This now requires only 56168 iterations
in smf_create_tempo_map_and_compute_seconds, rather than 1.64e+9
iterations
Now that we use superclock_t for audio time, it is possible for the square of an audio time value to overflow int64_t quite easily.
This change fixes that (and cleans up other code a little), but probably a different solution would be a good idea
