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MIDI Messages Are Crashing My Patch – How to Fix?

Nov 20 2010 | 12:58 am

Hi – I am using the MIDI sequencer on an Elektron Machinedrum to send midi messages to a jitter patch of mine. There’s 5 channels of midi, each with 6 CC messages. The jitter patch worked beautifully for hours when not connected to the machinedrum. Now that it is connected, and MIDI messages are being sent, the patch is consistently crashing after 5-20 minutes of use. How might I prevent this? Are there queue messages or something to discard MIDI info if the queue is getting too filled up?

Nov 20 2010 | 2:47 am

I don’t know about clearing the MIDI "cache", if there is one in Max or the OS, but you could try [change] and especially [speedlim] to thin out how many CC messages you’re getting. Try [speedlim 50] first, which is fast enough to seem like there’s nothing throttling it, then adjust to fit. This has helped me a lot in the past with similar issues.

If you find that something like [speedlim 250] will keep things from crashing better, and the update rate isn’t good enough, use [line $1 250] to smooth out the values (you could set the [line] time grain to 50 perhaps). While this will send more values to your eventual usage of the numbers (so it would seem like it’s a step backward), your crash might be related to the transfer of MIDI beforehand, not the values going into the jitter patch. To experiment, see if a patch will crash if you just show the raw CC messages as numbers, which I imagine it won’t. Then you can trace where the overrun happens, step by step… could be a backlog of jitter drawing/op commands down the line.

Nov 20 2010 | 2:56 am

Are you formatting the MIDI data by means of a message box (that is not getting cleared)?

Nov 20 2010 | 3:36 am

change and speedlim are excellent ideas.

"Then you can trace where the overrun happens, step by step… could be a backlog of jitter drawing/op commands down the line. "

"step by step" debugging is really hard when the crash is inconsistent. something could appear to be running fine, but actually be the culprit of the crash if it’s causing a memory leak, or something insidious like that.

to spectro, the MIDI messages are being sent to number boxes then scale objects.

Nov 20 2010 | 4:01 am

seems to be running smoothly after putting a change/speedlim message in front of every ctlin. also halved the size of the two objects to 320-240.

May 18 2011 | 10:44 am

Could I see your patch? Trying to experiement a bit with midi messages from my monomachine and in the future possibly a machinedrum, but it is a little harder to grasp than I thought.

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Forums > MaxMSP