Impulse/MIDI bug with a little speed?

dachy · Post by **dachy** » Sat Jul 08, 2006 2:32 pm

Hi,
I am wondering if there is a known issue with Impulse playing two samples at the same time under extreme MIDI conditions? I have the following situation..

I have built a hardware sequencer that sends a MIDI ON followed after a few microseconds by MIDI OFF. A few microseconds later I send another (different) note on and off. I am using these to trigger a snare and a bass drum respectively. In theory, I should hear both of these sounds play at the same time...

At a low BPM, Impulse has no problems playing both samples exactly as expected. However, if I increase the BPM a bit, I now start to notice that the first of the samples (snare) will playback incorrectly (or not at all). It seems to either be quiet, or produce a very short 'kzz' glitch sound (perhaps it plays for a very short amount of time. The bass drum sample is unaffected.

This does not occur with other samplers, for example Kontakt 2.

Interestingly, if I _record_ the received MIDI, and play it back, the problem disappears.

Please, can you let me know if this is related to some kind of quantization problem, latency compensation, or whatever other timing issues that might affect it. Is the recorded MIDI quantization somehow different from that played 'live' when using the monitor?

If this is an issue with abletons representation of midi time, I'd like some details. If it's simply an issue with Impulse, I can happily ignore it. I use live 5.0.3

justin · Post by **justin** » Sat Jul 08, 2006 6:08 pm

could this be caused by the record quantization setting?

perhaps if you switch it to off it will behave better...

dachy · Post by **dachy** » Mon Jul 10, 2006 12:25 am

I've had a look with MIDI-OX to examine the MIDI, both going into Ableton and out again. My live input consists of a note on, note off, note on and note off again, each on a consecutive timestamp. If this is recorded (without record quantization) and then played back, Ableton has destroyed this timing, instead it has, somewhere in the record/playback, manage to adjust the timing (sometimes up to 20 timestamps, but ususally by 3 or 4). I presume this modification is allowing Impulse to work correctly, but it's quite annoying.

It'd be very nice if someone can take a close look at their MIDI timing and let me know if they notice something similiar. If Ableton can suggest a workaround , that'd be super.

Thanks