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RedBaron
Topic Author
Posts: 345
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Re: Disadvantages of Large Process Buffer Range

Thu May 09, 2013 1:10 pm

Mark R wrote:
Idsz wrote:
...in my experience the buffer size has a tremendous impact on midi timing. I've set it to small after I tried to work for way too long with a large buffer range and was struggling with staccato's and percussion.


I can verify that when using Direct MIDI Input (such as a live keyboard) software instruments in Logic 9 will exhibit the "MIDI quantization by duration of the sample buffer size errors" discussed in the eigenzone.org MIDI Jitter link.

The same channel strip driven by a Recorded MIDI Region will play back fine however. (Perhaps in this more leisurely mode, Logic is programmed to take more care with exact MIDI timing while calculating the instruments audio output.)




Yeah, the eigenzone MIDI input Jitter tests are a credible piece of work.


But I think Idsz was talking about the Process Buffer Range affecting MIDI timing, not the I/O Buffer. But I'm not sure which timing he's referring to: internal MIDI (software instruments) or external MIDI.

dD
Logic X 10.2.4 / v9, Mini i7 2 GHz, El Cap 10.11.6
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Mark R
Posts: 392
Joined: Thu Jan 26, 2006 9:50 am
Location: Tumwater, WA

Re: Disadvantages of Large Process Buffer Range

Fri May 10, 2013 12:20 pm

Hi RedBaron,

Yes, the article helped explain that what we were hearing was beyond just latency. The added quantization of perceived MIDI timing in "Live Mode" is something that I though could be easily missed in this discussion, and I wanted to amplify this knowledge and show that it was also easily verifiable (external kybd arpeggio example).

Not sure either which setting Idsz was talking about, but his experience echoes my own, in being frustrated sometimes with "Live" MIDI timing in Logic (and MainStage).

I'm also interested in this issue because it is probably the hidden reason why the developer of Kirnu has shied away from recommending his own AU plugin, saying to use the VST version instead if possible. This might be an unnecessary caution because I'm now getting nearly perfect timing from Kirnu AU with dense MIDI streams on my quad core i7 mac mini.

This morning I am on the road with my slower 2009 core 2 duo macbook pro. And am testing Logic using Kirnu Cream to stream out 4 note chords every 16th note at 120bpm. I'm recording Cream's virtual MIDI output to another track (with ES2) for analysis.

Amid the commotion I'm finding that stopping and changing the 'Process Buffer Range' doesn't change my recorded "Live Mode" results (on this here core 2 duo).
But I see a huge difference in Jitter as I change I/O Buffer Sizes.
Buffer set to 32 samples - I get 4 ticks of Jitter
Buffer set tp 1024 samples - I get 45 ticks of Jitter.

The takeaway is that small Audio I/O Buffer Sizes minimize not only latency, but also "Live" MIDI timing.
Logic 10.5.1 | Mojave | retina iMac 4GHz i7 32GB
Logic 10.4.8 | High Sierra | MacMini 2.3GHz, i7 16GB
 
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CShorte
Posts: 211
Joined: Tue Feb 19, 2008 9:38 am
Location: Washington DC Metro Area

Re: Disadvantages of Large Process Buffer Range

Tue Sep 23, 2014 8:57 am

Having read this thread and having been experiencing some MIDI note lag after the track had been prepped with some MIDI information, I tried lowering my buffer size from 128 to 32 KB. This produced more jitter and cracking and popping then was expected even while there was no sign that a processor was being overloaded. Then I tried a buffer size of 256; I was still getting the delayed MIDI notes.

In my case, the MIDI notes were being recorded but they did not sound while being recorded or during fast passages while playing. In the end, I decided to disable the iPad Logic Remote application. I have not heard any problem since disabling the iPad app. If there is a change to this status, I will update my response but for now, I will avoid the iPad Logic Remote app.
MacPro: 8-core 3 GHz, 1 TB SSD, 32 GB Memory, OSX 10.12.6;, HD: 4 Drive TB Array w/ 4 * 3 TB HDs
Audio: Apogee SymphonyAD/DA-16x, 2 Digimax FS

Software: LP v9.1.8; LPX 10.3.2; Cubase Pro v9.x; Halion v3.x; Finale 2016; Groove Agent v3; NI Kore v2, NI Komplete v10; Sibelius v7.5; Omnisphere; Waves Platinum, SSL 4000, CLA Signature Collection; VSL SE v1&2, Instruments Pro, VE Pro
 
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CShorte
Posts: 211
Joined: Tue Feb 19, 2008 9:38 am
Location: Washington DC Metro Area

Re: Disadvantages of Large Process Buffer Range

Wed Sep 24, 2014 10:00 am

CShorte wrote:
Having read this thread and having been experiencing some MIDI note lag after the track had been prepped with some MIDI information, I tried lowering my buffer size from 128 to 32 KB. This produced more jitter and cracking and popping then was expected even while there was no sign that a processor was being overloaded. Then I tried a buffer size of 256; I was still getting the delayed MIDI notes.

In my case, the MIDI notes were being recorded but they did not sound while being recorded or during fast passages while playing. In the end, I decided to disable the iPad Logic Remote application. I have not heard any problem since disabling the iPad app. If there is a change to this status, I will update my response but for now, I will avoid the iPad Logic Remote app.


Logic Remote has an update to v1.1.1; it appears that the issue stated above has been corrected. No more lost notes due to network accessing. However, whenever I change the focus from LP to another app, the Logic Remote disconnects from LP.

To the Moderator(s), if these comments should be in a separate thread, please let me know and I will create another thread. Thanks, CS.
MacPro: 8-core 3 GHz, 1 TB SSD, 32 GB Memory, OSX 10.12.6;, HD: 4 Drive TB Array w/ 4 * 3 TB HDs
Audio: Apogee SymphonyAD/DA-16x, 2 Digimax FS

Software: LP v9.1.8; LPX 10.3.2; Cubase Pro v9.x; Halion v3.x; Finale 2016; Groove Agent v3; NI Kore v2, NI Komplete v10; Sibelius v7.5; Omnisphere; Waves Platinum, SSL 4000, CLA Signature Collection; VSL SE v1&2, Instruments Pro, VE Pro