Ableton Forum

For All of you broken midi folks out there...

I have the same problems with midi latency, except in Pro Tools, not live... I have had several issues bought to my attention about midi latency problems.

1) How long are your midi cables to and from your instruments? Midi cables are just like resistors, the longer they are, the greater the impeadance, this can equal latency. Keep your cable runs as short as possible and use good quality cables.

2) Midi gets processed through a number of sources. Just like a long midi cable adding latency, so too, delays can be caused by the midi signal being processed through multiple stages, processors, from the APP into the midi driver, then into the interface, then the instrument, and back to the computer, and back into the app. I have seen this add up to several ticks or more depending on the amount of processing in-line. Each element in the chain takes a small amount of time to process. This can add up, and the time is variable in every instance.

3) I have noticed, in Protools, that if I play a midi instrument back using midi only and buss it to an audio record channel as a monitor, that the track lines up fine on playback... but when I commit the midi track to an audio by recording it, I see that latency is a result. I beleive that going through the audio engine to the disk adds several Milliseconds of latency, so my audio files also do not line up as well.

What I am saying in short is that, while we would all like to blame a peice of software for all of these problems, that latency compensation is not a miracle... It can't judge the length of your cable, or the quality, or how many stages the midi signal travels through in the external world to get back into the internal.

I have found myself carefully measuring the lost ticks, or samples, and moving or advancing the track to compensate for this. I have observed that the number I come up with is often not the same number that compensation algorithms come up with.

Just like in the audio realm, where there are various causes of signal degradation and audio latency, so too this exsists in the midi realm. One has to take the responsibility of an audio engineer, and analytically engineer an understanding of, and a workaround for these issues.

That is what engineering is... We can't expect Ableton or digidesign to be psychic about what we're doing inside and out of our rigs. As well, it is unfair to expect that while electricity moves at the speed of light, that everything in between will offer no resistance or latency.

I beleive that there needs to be certain conditions present for this to occurr.

1) Everything in the system must be either cooled to absolute zero, or cooled to about minus -473 degrees farenheit. Or must be bathed in liquid nitrogen cooling.

2) The circuits must be located in the perfect vaccuum of outer space if the previous cooling suggestions cannot be used. This will also provide the appropriate cooling for electrical circuits to operate with 0 resistance.

I dont expect either Ableton or Digidesign to release a version like that any time soon. And I'm sure that the cost would be astronomical.

Regards
Sunsinger

All Puns intended

Length of cable does not affect latency. There is some propagation delay within the cable but this is measured in nanoseconds not anything one could hear.

Any midi cable will degrade the signal due to its collective resistance and capacitance. At around 5m long this degradation could be severe enough to cause hung notes, missed notes and other erroneous behaviour. A poorly constructed cable would be worse in this respect, but even the best cables have problems over 10m.

Midi thru outputs do suffer from some delay compared to the input signal. But, some do it better than others.

Some have what is called 'soft thru', this means that the CPU of the hardware unit has actually processed the signal and there will be some delay. Its usually pretty quick these days though.

Hardware thru outputs are very quick and any latency can normally be ignored. However, what they can do is introduce skew. This is complex to explain fully, but all you need to know is that the midi signal does become degraded slightly as it passes through the hardware. Too many thru chains and you could find your midi signal becoming corrupted enough to notice. Particularly if there is a lot of information going through it, multiple channels, CC messages, MTC etc.

Generally one should avoid midi daisy chains of more than three units. With todays multiple midi output ports there is no need for this anyway.