[PD] midi latency

[Johannes Taelman]

Hi all,

On win2k I observed 25 ms latency over a midi loopback with about 2.5 ms
jitter on average. Is there a way to reduce the midi latency? Where is
the bottleneck? Is it better on linux?

I also observed that my hammerfall dsp midi interface does 25ms while my
midiman usb midisport 4x4 needs 30ms.

regards,
 j#|@


here's a test patch (midilatency.pd):

#N canvas 291 416 644 359 12;
#X obj 9 43 tgl 15 0 empty empty test 0 -6 0 8 -262144 -1 -1 1 1;
#X obj 113 174 timer;
#X obj 97 123 ctlin 1;
#X floatatom 92 34 5 0 0 1 midi_port_number - -;
#X obj 92 77 + 1;
#X obj 92 54 * 16;
#X floatatom 113 196 5 0 0 1 latency - -;
#X floatatom 113 237 5 0 0 1 average_latency - -;
#X msg 9 152 0;
#X obj 113 215 average 100;
#X obj 9 122 metro 100;
#X text 5 8 measure the midi latency with a loopback cable;
#X obj 9 174 ctlout 1 1;
#X obj 148 149 select 1;
#X obj 94 258 -;
#X obj 94 282 abs;
#X floatatom 94 326 5 0 0 1 average_jitter - -;
#X obj 94 304 average 100;
#X msg 45 91 50;
#X text 238 60 hammerfall dsp \, win2k \, ASIO -> 25 ms;
#X text 239 76 midisport 4x4 \, win2k \, ASIO -> 30.5 ms;
#X connect 0 0 10 0;
#X connect 1 0 6 0;
#X connect 2 1 13 0;
#X connect 3 0 5 0;
#X connect 4 0 12 2;
#X connect 4 0 13 1;
#X connect 5 0 4 0;
#X connect 6 0 9 0;
#X connect 6 0 14 0;
#X connect 7 0 14 1;
#X connect 8 0 12 0;
#X connect 9 0 7 0;
#X connect 10 0 1 0;
#X connect 10 0 8 0;
#X connect 13 0 1 1;
#X connect 14 0 15 0;
#X connect 15 0 17 0;
#X connect 17 0 16 0;
#X connect 18 0 10 1;