Go Back   Cockos Incorporated Forums > REAPER Forums > REAPER Q&A, Tips, Tricks and Howto

Reply
 
Thread Tools Display Modes
Old 11-23-2015, 11:55 AM   #1
Airal
Banned
 
Join Date: Nov 2015
Posts: 406
Default Timing Jitter Loop Back Test Setup(Participation Request)

This test uses an electronic drum kit since it can be controlled using audio. By hooking up an audio output to the input of a drum sensor, you can trigger a "drum hit" that the E-drum module will convert to midi.

This can be represented by the loop

[Reaper] Click Track -> [Audio Interface] Line Out -> [EDrums] Sensor -> Module -> Midi Out -> [Audio Interface] Midi In -> [Reaper] Recorded Midi Track.

With such a setup, we can compare the latency between the click track in reaper and the final recorded track.

Having done so, my results are around 6ms average and 11ms max jitter. From reading online, this seems to be a bit unacceptable.

I've written a python script that computes the jitter between midi note clusters(notes within 50ms or so are considered to be in the same group) in a midi item. Once the track is recorded, you'll have to add the midi notes by hand(or glue a pre-created midi click to the recorded one).

I'm interested in what kind of results others gets.

The gear used in the test: i7-6700k, 16GB DD4 mem, etc; US-1800 Audio Interface, Roland V Drums.

---

The test was just hacked together when I get the bright idea to use the drums as a way to do midi loop back timing test using audio as a controller(since the drums I have do no have an input which can then). One can achieve a similar test that only includes the audio interface(loop back on the midi ports). I suppose that is the next test to do, as it will allow one to know the jitter the midi drums have themselves, which allows one further break down the analysis.

If someone has an improved testing method with scripts to do the calculations or ways to improve the jitter, I'd appreciate it. Obviously as a drummer, it is important to minimize all latency and jitter issues as milliseconds matter.

(I have a theory that if you have x ms latency and use an E drum kit, then when you practice, you compensate by x ms to "be on the beat". Then when you get on an acoustic kit you tend to rush by x ms because the latency is not there. This is generally not a big deal until you start trying to sync stuff up with an acoustic kit and your constantly in front of the beat, yet your fine on your e-drums)

Last edited by Airal; 09-04-2016 at 04:49 PM.
Airal is offline   Reply With Quote
Old 11-24-2015, 01:11 PM   #2
Caustic
Human being with feelings
 
Caustic's Avatar
 
Join Date: Jan 2009
Posts: 317
Default

i have done similar tests with mpc2500 which has a large amount of jitter itself, it cant be tested in the same way except with threshold sampling but the mpcs sequencer jitter is whats really inconsitent and changes timing a little bit on each beat, i gave up testing when i worked this out.
Caustic is offline   Reply With Quote
Old 11-28-2015, 10:52 PM   #3
Airal
Banned
 
Join Date: Nov 2015
Posts: 406
Default

Unfortunately it is a serious issue since ms's do count but most non-musical people(programmers?) don't get this and they create their programs that lack the capability to deliver consistently.
Airal is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 12:03 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.