Latency by Connection Type

[sven hauck]

I was wondering if there is any impact on latency based upon how a midi controller is connected. If you connected the same midi controller 3 different ways:

1. Midi
2. USB
3. Firewire

What is the impact, if any, of each connection to the latency?

[admin]

The midi one should have the most as midi itself is slower than both of the other options. The only reason I'd do th midi connection would be if the drivers for the other two options weren't stable. That being said even the midi option would only incur about 1ms of delay which shouldn't be noticeable at all.

[Rambunkcious]

To add to what medway was talking about the drivers, i remember reading somewhere that USB wasnt designed as a "realtime" or a "streaming" protocol, dont know if i used the right terminology there, so the driver is really taking care of that as opposed to Firewire, or midi.

I guess kind of the same reason that major DAW's prefer you use firewire, SCSI, or SATA instead of USB harddrives, I know Pro Tools does not accept USB hardrives at all, to record on or playback from.

[sven hauck]

True, I was just wondering since data from a keyboard/controller is relatively small when you bang out a few notes here and there, whether Firewire performed better than USB. My assumption was that the difference is negligible.

However, when it comes to moving large amounts of data, the bandwidth advantage lies clearly with Firewire.

[admin]

By rough calculations USB should be far away from the bandwidth needed for MIDI. A MIDI note is about 3 bytes and this takes about 1ms to travel. So thats 3000 Bytes per second. USB 1.1 is 1.5 Megs per sec, 2.0 is 60 Megs per sec, so quite a bit higher. Any jitter or latency should happen in the drivers/OS and not the bandwidth itself which is more than capable.

[admin]

In fact to put in perspective how slow MIDI is...back in the days before SCSI and USB we had to use MIDI to transfer samples from the computer and sampler. A single 4 bar loop would literally take 5 minutes...

[sven hauck]

I'd run out of patience with that thing. Thank god for the Digital Audio Workstation!

[admin]

It's amazing now to think I can run though gigs of loops all timed to my current bpm now no hassle. I can remember getting out a pen and paper to calculate sample positions based off time and sample rate for chopping loops

[sven hauck]

Now that shows you're old school.

[admin]

Oh and that was in hexidecimal too