Reference Manual

587 MIDI Fact Sheet

converter‘s output is then recorded into a new audio clip in Live. In an ideal system, each event

in the MIDI clip would occur simultaneously with the corresponding event in the audio clip. Thus

the difference in timing between the MIDI and audio events in the two clips can be measured to

determine Live‘s accuracy.

In order to assess MIDI performance under a variety of conditions, we ran the tests with three

different audio/MIDI combo interfaces at different price points, all from well-known manufac-

turers. We will refer to these interfaces as A, B and C. All tests were performed with a CPU load

of approximately 50% on both OS X and Windows machines, at both 44.1 and 96 kHz and at

three different audio buffer sizes, for a total of 36 discrete test conﬁgurations.

Windows:

•Interface A: The maximum jitter was +/- 4 ms, with the majority of the jitter occurring at +/-

1 ms.

•Interface B: For most of the tests, the maximum jitter was +/- 3 or 4 ms. At 96 kHz and

1024 sample buffer, there were a small number of events with +/- 5 ms of jitter. At 44.1

kHz and 512 sample buffer, occasional events with +/- 6 ms occurred. In all cases, the

majority of the jitter occurred at +/- 1 ms.

•Interface C: For most of the tests, the maximum jitter was +/- 5 ms. At 96 kHz and 512

sample buffer, there were a small number of events with between +/- 6 and 8 ms of jitter.

At 44.1 kHz and 1024 sample buffer, there were a small number of events with jitter as

high as +/- 10 ms. In all cases, the majority of the jitter occurred at +/- 1 ms.

OS X:

•Interface A: At 44.1 kHz and 1152 sample buffer, jitter was fairly evenly distributed be-

tween +/- 4 and 11 ms. For all other tests, the maximum jitter was +/- 5 ms. In all tests, the

majority of the jitter occurred at +/- 1 ms.

•Interface B: For most of the tests, the maximum jitter was +/- 4 or 5 ms. At 44.1 kHz and

1152 sample buffer, there was a fairly even distribution of jitter between +/- 2 and 11 ms.

In all cases, the majority of the jitter occurred at +/- 1 ms.

•Interface C: In all tests, the maximum jitter was +/- 1 ms, with most events occurring with no

jitter.

We also performed a similar procedure for testing the timing of outgoing MIDI events, as repre-

sented in the following diagram: