[LAD] Midi Beat Clock to BPM

Hi

I try to fetch the bpm from the Midi Clock, and stumble over "jitter".
So I start to collect data for a larger amount of time, but it wouldn't
help.

Here is what I do:

else if ((in_event.buffer[0] ) == 0xf8) { // midi beat clock
             clock_gettime(CLOCK_MONOTONIC, &ts1);
             time0 = (ts1.tv_sec*1000000000.0)+(ts1.tv_nsec);
             static int collect = 0;
             static int bpm = 0;
             bpm += ((1000000000 / (time0-time1) / 24) * 60); // nanosec
to bpm
             collect+=1;

             if (collect >=30) {
               set_bpm_val(bpm/collect);
               collect = 0;
               bpm = 0;
             }
             timed = time0-time1;
            // printf("Midi clock event %X time0 %f time1 %f timed %f
ts1.tv_nsec %lu\n",in_event.buffer[0], time0, time1, timed, ts1.tv_nsec);
             time1 = time0;
         } else if ((in_event.buffer[0] ) == 0xfa) { // midi clock start
             printf("Midi clock start\n");
             //set_ctr_val(MIDICLOCK, 1);
         } else if ((in_event.buffer[0] ) == 0xfb) { // midi beat
clock continue
             //set_ctr_val(MIDICLOCK, 1);
             printf("Midi clock continue\n");
         }else if ((in_event.buffer[0] ) == 0xfc) { // midi beat clock
stop
             //set_ctr_val(MIDICLOCK, 0);
             printf("Midi clock stop\n");
         } else {
             printf("CC number %x\n", in_event.buffer[0] );
         }

tim0 and time1 are set as double.
I experience jitter around 1 or 2 beats around the "original bpm set in
the master.
When master is set to 360 I receive 374.

How do you usually fetch the bpm from Midi Clock, any pointer will be
welcome.

regards
hermann
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Received on Sun Nov 2 00:15:04 2014