View Issue Details
|ID||Category||Date Submitted||Last Update|
|0008054||bugs||2020-04-24 19:33||2020-05-27 11:12|
|Platform||GNU/Linux x86_64||OS||Debian||OS Version||sid|
|Fixed in Version|
|Summary||0008054: MIDI calibration does not produce expected results like Audio calibration does|
|Description||After calibrating audio, if the cable used for calibration remains connected, Ardour’s metronome click is routed through that cable, and an audio track’s input is feed with the hardware input where that cable is connected, once several beats are recorded for that audio track, it will capture the metronome click wave perfectly synchronized with every beat line. However, that is not the case for a MIDI track.|
|Steps To Reproduce|| 1. Go to “Window” > “Audio/MIDI Setup” > “Midi Device Setup” and calibrate any MIDI device.|
2. Calibrate any MIDI device. Do not disconnect the cable used for calibration.
3. Create two MIDI tracks without any instrument.
4. Route the output of the first MIDI track to the MIDI out port where the calibration cable is connected.
5. Route the input of the second MIDI track to the MIDI in port where the calibration cable is connected.
6. Add some quarter notes per beat in the first MIDI track.
7. Arm the second MIDI track, toggle on the record button and click the play button.
Expected: The recorded MIDI notes from the second MIDI track are synchronized with the beat lines, like in the first MIDI track.
Actually: The recorded MIDI notes from the second MIDI track are not synchronized with the beat lines.
|Tags||No tags attached.|
bug6.png (149,579 bytes)
bug6.png (149,579 bytes)
I have just realized that below results I got with more experiments and I posted in the forum are better to be added here:
I have been investigating and I have observed some interesting behavior when changing the buffer size, that I didn’t realize the first time I did these tests. The recorded notes from the armed MIDI tracks (see above image) have a delay that is proportional to the audio size buffer. For instance, with a buffer of 256 samples, I got a delay of 234 and 261 samples, and with a buffer of 1024 samples, I got 998 and 1098.
So, in some way MIDI is tied to audio, no? Also, switching the periods from 3 to 2 arose these results:
1024|3: detected roundtrip latency 3141 samples (65,4 ms); systemic latency 1093 (22,8 ms).
1024|2: detected roundtrip latency 2119 samples (44,1 ms); systemic latency 71 (4,5 ms).
However, the recorded notes are delayed by the same amount in both cases, no matter the number of periods.