[chuck-users] Latency Vs Midi timings precision

[Mario Buoninfante]

Hi Julien,

as far as I know the best thing to do should be to set the period buffer to
3, at this point you could easily decrease the buffer size both on Jack and
ChucK (you can find more info on Linux audio website or just googling). in
my setup at the moment I have the buffer size on Jack = 256 and on ChucK =
512 and it works fine. I've got an average Asus machine, i5 (5th or 6th
generation) with 8gb of RAM. but unfortunately MIDI on ALSA driver is not
as accurate as CoreAudio is. let's say it's well known to introduce jitter.
so I suspect the problem lies there.

cheers,
Mario

2018-03-19 16:03 GMT+00:00 Julien Saint-Martin <
julien.saintmartin at googlemail.com>:

> Hi Mario,
>
> In qjackctl my config is (my parameters names are in French so maybe my
> translation is not the exactly same) :
> Samples/Period: 4096
> Sample rate: 44100
> Period/Buffer: 2
>
> Midi Driver: None
>
> I call ChucK (Jack version) with parameter --bufsize8192
>
> What is the specific setup your are talking about ?
>
> Thanks!
> Julien
>
>
>
> 2018-03-19 15:16 GMT+01:00 Mario Buoninfante <mario.buoninfante at gmail.com>
> :
>
>> Hi Julien,
>>
>> I work on Linux as well, using Jack as audio core. there's a specific
>> setup I've got that uses ChucK as slave (an external hardware sends MIDI
>> clock to it and Pure Data). I have to say I've never experienced  anything
>> like this, but honestly this specific ChucK script I'm using is in sync
>> with everything, but doesn't need to be super accurate. So I've never
>> measured if performance in this situation. could you provide some info more
>> about your settings? how are you setting latency? buffer size on Jack,
>> ChucK?
>>
>> cheers,
>> Mario
>>
>> 2018-03-19 11:11 GMT+00:00 Julien Saint-Martin <
>> julien.saintmartin at googlemail.com>:
>>
>>> Hi there,
>>>
>>> I am trying to synchronize my ChucK Loops and Synth with a friend.
>>> We use midi messages and I am Slave.
>>> I use Linux with Jack server.
>>>
>>> To ensure ChucK processing without glitches I play with latency (usually
>>> 186 ms).
>>> But I noticed that perdiodic midi messages are randomly delayed (kind of
>>> jitter of about 80ms) when received in ChucK.
>>> I also noticed that the jitter decrease when I reduce Latency.
>>>
>>> Latency is not a problem for me, and it is needed for Chuck to compute
>>> without glitches (XRun in Jack server).
>>>
>>> Do you know where the Jitter comes from (Linux, Jack, ChucK) ?
>>> Is  there a solution to reduce it keeping some latency ?
>>>
>>> Happy Chucking,
>>>
>>> Julien
>>>
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>>>
>>>
>>
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