Hi, I resume this old thread because I compiled pd with Miller's advices to disable MIDI buffering. I tested it with a patch (attached) and this configuration: vkeyb-MidiOUT(ch1) -> pd-MidiIN pd-MidiOUT -> pd-MidiIN so, every time I play a note, I see how much time it takes to pass through pd. I made this test because in my configuration I place pd between my MIDI devices and synth, samplers, etc. The first thing I noticed is that the latency no longer depends on JACK buffer(frames/period), even with the "-jack" startup flag, and the results are:
- With the "-jack" flag, the latency was always 1.45ms
- With the "-noaudio" flag, the latency was 0ms (sometimes 1.45ms)
Just to compare with the standard pd, the best result I achieved is 1.45/2.9ms with "-noaudio".
Nicola
Il 27/11/2012 18:50, Miller Puckette ha scritto:
I believe if you edit s_midi.c and change:
if (midi_outqueue[midi_outtail].q_time <= midirealtime)to
if (1)
and
if (midi_inqueue[midi_intail].q_time <= logicaltime)also to
if (1)
that will make it fast-as-possible. The queueing code should probably be surrounded by an ifdef to make this easier (perhaps someday...)
cheers M
On Tue, Nov 27, 2012 at 06:23:15PM +0100, Cyrille Henry wrote:
Is there a way to bypass all of this? my pd usage usually imply sending and receiving as fast as possible. sending delay usually annoy me. cheers c
Le 27/11/2012 18:06, Miller Puckette a écrit :
Pd tries to time-stamp MIDI on input and tries to delay sending MIDI output until the correct time; but Pd's accuracy in doing this is limited by the fact that it can't input or output MIID while it is either sleeping or running (only when the scheduler polls for what-to-do-next after either a task or a sleep has finished.)
It would be more accurate for Pd to rely on either software interrupts or even better on some underlying OS time-tagging mechanism (for instance by exploiting whatever portmidi does). But I have to admit I've never treated this as a high priority (which one might take as an implied value judgement about MIDI).
cheers Miller
On Tue, Nov 27, 2012 at 11:44:06AM +0100, Cyrille Henry wrote:
Le 27/11/2012 10:36, IOhannes m zmoelnig a écrit : ...
with MIDI, Pd doesn't do any buffering and no synchronisation to some external clock is done, so messages appear in bursts which you notice as a inaccurate timing.
There is 1 strange thing however : pd did some kind of buffering with midi, in order to synchronise with audio out. if you configure 100ms audio latency, then a midi loop will be between 100 and 105ms. with 10ms audio buffer out, the midi loop is between 10 and 15ms. but this buffer should not change anything on timing except adding latency. cheers c
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