MIDI track, external synth and loop region

[vdh2137]

Hi,
I have some strange issue when using MIDI with external synth: when I create a loop region, it plays fine for the first time, next rounds are somehow chopped at the beginning. Same issue on 8.12 and 9. It is only related to loop, everything works fine, even if I’m playing on external USB MIDI keyboard.

The upper audio track is a first take from looped recording, the bottom one is from second loop.

It works fine for software synth. Same results on a2jmidi and pipewire.

[x42 (Robin Gareus)]

Looks like the incoming Audio is delayed. The latency (midi out → audio in) is not compensated for.

Have you calibrated systemic latency?
With Arodur/ALSA that is directly available in Ardour Menu > Window > Audio/MIDI Setup

With pipewire, you have to manually measure it (e.g. jack_iodelay, and set it manually).I don’t know if this became easier these days or of pw-cli is still the way to go:

How does PipeWire perform with Ardour?

Keep in mind that configuring low latency with Pipewire still requires some significant knowledge, particularly with USB devices. Another aspect that is rather complex is to configure systemic-latency. For jackd those are simply command-line options -d alsa -I <num> -O <num>. and jack_iodelay directly suggests those. You will notice that when recording overdubs in Ardour. They won’t align with pipewire. The solution here is to first measure the round-trip latency (using jack_iodelay). Then y…

[songo (Krzysztof Gajdemski)]

@x42

Looks like the incoming Audio is delayed. The latency (midi out → audio in) is not compensated for.

But if you look closely at the recorded audio, only the first note is seriously “delayed”. In fact, it’s somewhat chopped at the beginning… which is strange. Maybe the characteristics of the OP’s device and/or patches have something to do with it.

But I’m investigating a very similar issue right now, which I think may be related. As can be seen, in my case the first looped note is also chopped – but just after the beginning:

This happens because when the loop restarts, Ardour sends the All Notes Off messages (and Damper Pedal Off as well, though it is irrelevant here):

Although the All Notes Off messages arrive first at the beginning of the loop, it is enough to silence the first note shortly after it starts. I don’t yet know the exact mechanism behind this, but filtering out controller 123 solves the issue for me.

Checked it on two different MIDI interfaces and several synths, and the behavior is the same. Please note that sending the messages to all channels also stops other sustained notes that might be played across the loop, breaking the performance… It would be extremely useful to have an option to disable this behavior.

To the OP: maybe try filtering out Controller 123 and see if that helps? Not sure if it’s possible in Ardour because this is added after the processors AFAIK. I’m doing this in the hardware.