ardour/ardour
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fix incorrect handling of MIDI data by AsyncMIDIPort

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This type of MIDI port fetches all of its data from inside ::cycle_start(),
and delivers it to a FIFO connected to another thread (typically a
control surface).

Unlike regular MidiPorts, which will be read from inside a Session::process()
call, these ports will read their data once per AudioEngine::process() cycle.
They therefore cannot use MidiPort::get_midi_buffer() which scales and adjusts
event timestamps as if the data is being accessed from within Session::process().

It is still an open question whether or not AsyncMIDIPort::cycle_start() should
still scale event timestamps by speed. In some respects it seems more appropriate
to do so, and the reading thread (e.g. a control surface) doesn't care about
the "nframes" limit on timestamps that exists for calls within a Session::process()
tree. For now, leave the timestamps unscaled by speed.
This commit is contained in:
Paul Davis 2020-02-24 18:44:45 -07:00
parent 42c13607a2
commit 4749fcef86
1 changed files with 24 additions and 13 deletions
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37
libs/ardour/async_midi_port.cc
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@ -131,23 +131,35 @@ AsyncMIDIPort::cycle_start (MIDI::pframes_t nframes)
*/
if (ARDOUR::Port::receives_input()) {
MidiBuffer& mb (get_midi_buffer (nframes));
samplecnt_t when;
if (have_timer) {
when = timer ();
} else {
when = AudioEngine::instance()->sample_time_at_cycle_start();
}
void* buffer = port_engine.get_buffer (_port_handle, nframes);
const pframes_t event_count = port_engine.get_midi_event_count (buffer);
for (MidiBuffer::iterator b = mb.begin(); b != mb.end(); ++b) {
if (!have_timer) {
when += (*b).time();
for (pframes_t i = 0; i < event_count; ++i) {
pframes_t timestamp;
size_t size;
uint8_t const* buf;
port_engine.midi_event_get (timestamp, size, &buf, buffer, i);
if (buf[0] == 0xfe) {
/* throw away active sensing */
continue;
}
input_fifo.write (when, Evoral::NO_EVENT, (*b).size(), (*b).buffer());
samplecnt_t when;
if (have_timer) {
when = timer ();
} else {
when = AudioEngine::instance()->sample_time_at_cycle_start() + timestamp;
}
input_fifo.write (when, Evoral::NO_EVENT, size, buf);
}
if (!mb.empty()) {
if (event_count) {
_xthread.wakeup ();
}
@ -346,4 +358,3 @@ AsyncMIDIPort::is_process_thread()
{
return pthread_equal (pthread_self(), _process_thread);
}