RT MIDI

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Drumfix
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Re: RT MIDI

Postby Drumfix » Fri Dec 07, 2018 7:23 am

If using a USB audio/midi device make sure that the ksoftirqd process on the core where the USB host controller irq is running is also running at realtime priority. And move away all other irqs from this core.

merlyn
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Re: RT MIDI

Postby merlyn » Mon Dec 10, 2018 8:44 pm

raboof wrote: Looks like the MPU-401 had a Pulses-Per-Quarter-Note (PPQN) of 24


24 seemed like a strange number until I realised the significance of 24 = 2 * 3 * 4

1 tick = 64th note triplet
2 ticks = 32nd note triplet
3 ticks = 32nd note
4 ticks = 16th note triplet
6 ticks = 16th note
8 ticks = 8th note triplet
12 ticks = 8th note

That means this old standard had a musical time base, in contrast with a modern system that uses the sample rate as the time base.

merlyn
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Re: RT MIDI

Postby merlyn » Wed Dec 12, 2018 1:54 am

I found this on the Ardour blog :

Paul Davis wrote:There is a lot of work to do on Ardour's MIDI workflow. But before that can happen, there are several subtle errors that are caused by the way released versions of Ardour have handled musical time. When you edit and move a MIDI note forward by a quarter note, that process would actually involve several conversions back and forth between time measured in samples and time measured in musical units, and the result is (often) small errors accumulating that lead to the note beginning and end being "wrong".

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khz
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Re: RT MIDI

Postby khz » Thu Mar 07, 2019 1:21 pm

- https://www.midi.org/articles-old/the-midi-manufacturers-association-mma-and-the-association-of-music-electronics-industry-amei-announce-midi-2-0tm-prototyping,
- https://www.midi.org/articles-old/rtp-midi-or-midi-over-networks.

This article describes limitations of the MIDI standard and shows ways to get around several issues by increasing transmission speed and controller resolutions. Read here about the limitations of MIDI.

Source: http://www.96khz.org/oldpages/enhancedmiditransmission.htm
Most PC's limit seems to be 460kBaud, which I achieved using Linux and the wxWidgets Library. See my PDF-document here for a detailed explanation provided for Joachim Bürmann. http://www.iftools.com (CTB library). With 460kBaud piano control in real-time is principally possible. With special hardware, even 920kBaud is possible using Linux. So from the PC side, it was possible to switch to an enhanced MIDI standard with increased speed.

The article is from the year 2000. :-)
FZ - Does humor belongs in Music?
GNU/LINUX@AUDIO ~ /Wiki $ Howto.Info && GNU/Linux Debian installing >> Linux Audio Workstation LAW
    I don't care about the freedom of speech because I have nothing to say.


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