Re: [Jack-Devel] Dispersing MIDI messages: one to multiple
JACK processing happens in "buffers" of "nframes" size. When you're
writing MIDI, you can specific at exactly what audio-frame this event
took place: that's the time parameter.
Dropouts are bad - regardless of how you want to use the software now,
design it to not drop out. Also, since audio and MIDI are
sample-accuratly in sync in JACK, if you drop audio frames, you're
also dropping MIDI data.
Did you fix the loop midi_event_get() code?
for(i = 0;i<n;i++){
res = jack_midi_event_get(&jev,in_port_buf,i);
You're not checking the number of events available - and attempting to
"get" one event for every frame. The code I posted previously has the
fix.
Cheers, -Harry
PS: When replying, keep the list in the CC; i made the mistake of a
direct reply on my first reply too - my bad :)
On Thu, Jan 29, 2015 at 1:19 PM, Marjan Mrak <[hidden]> wrote:
> Hey Harry, thanks for a quick answer.
>
> I think, dropout happens on "audio" level, not at MIDI. I recorded output to
> waw; during recording, sound on speakers "dropped" for a moment, but WAV
> contents was fine.
>
> Thanks for suggestion, however there is a flag in my code ( if(verb == 1)
> ), through which I can ommit printf-ing completely.
>
> Would you be so kind as to explain to me, what jack_nframes_t time parameter
> in jack_midi_event_write represents? Sequence? Can it be of same value for
> all calls?
>
> Bye,
> Marjan
>
> 2015-01-29 13:46 GMT+01:00 Harry van Haaren <[hidden]>:
>>
>> Hey,
>>
>> I'm not sure why it would "hang", and I'm not sure quite what you mean
>> with that: are notes not passed through at all, or is it that certain
>> notes are skipped?
>>
>> I hope its the latter.. because there's a little bug hiding in the
>> MIDI get code from JACK. It attempts to read *one* event, for every
>> "nframe" that is available. The following code snippet is taken from
>> the JACK example-clients - midisine.c
>>
>> jack_midi_event_t in_event;
>> jack_nframes_t event_index = 0;
>> jack_nframes_t event_count = jack_midi_get_event_count(port_buf);
>>
>> if(event_count > 1)
>> {
>> printf(" midisine: have %d events\n", event_count);
>> for(i=0; i<event_count; i++)
>> {
>> jack_midi_event_get(&in_event, port_buf, i);
>> printf(" event %d time is %d. 1st byte is 0x%x\n", i,
>> in_event.time, *(in_event.buffer));
>> }
>> }
>>
>> I'm not sure if your code is "production ready" - printf locks a
>> mutex, a big no-no in RT code. Since MIDI handling and audio are in
>> the same real-time thread, its not wise to printf in production code.
>> It could cause xruns in JACK if the printf decides to lock and wait
>> too long.
>>
>> Hope the above helps the issue, cheers, -Harry
>>
>>
>>
>> On Thu, Jan 29, 2015 at 10:08 AM, Marjan Mrak <[hidden]>
>> wrote:
>> > Hello all,
>> >
>> > I have following question:
>> >
>> > I have developed JACK MIDI client, which grabs midi messages from MIDI
>> > keyboard on one port, and disperses it according to:
>> >
>> > * if message is controlled message (functional button was pressed on
>> > MIDI
>> > keyboard), it's changed to "volume control" and to certain channel and
>> > transmited
>> > * if message is "key up" or "key down", it's dispersed to channels from
>> > 1 to
>> > 4.
>> >
>> > It works, but if I am using it, totaly at random sound output "hangs"
>> > for
>> > like 10th of second.
>> >
>> > I suspect my code is the problem. I would just like someone to examine
>> > it -
>> > perhaps I am doiung something wrong here.
>> >
>> > Or is there a better way to "disperse" one MIDI message to several
>> > channels?
>> >
>> > I tried to find more detailed description of API than official docs
>> > (which
>> > is... basic, I'd say), but no luck.
>> >
>> > Thanks for any help or assistance in advanced!
>> >
>> > Following is my processing callback:
>> >
>> > static int process(jack_nframes_t nframes, void *arg)
>> > {
>> > int res = 0;
>> > int i;
>> > int j;
>> >
>> > //unsigned char* buffer;
>> > unsigned char jbuffer[3];
>> >
>> > void* port_buf = jack_port_get_buffer(output_port, nframes);
>> >
>> > //get events
>> > void* in_port_buf = jack_port_get_buffer(input_port, nframes);
>> > jack_nframes_t n = jack_midi_get_event_count(in_port_buf);
>> >
>> > jack_midi_clear_buffer(port_buf);
>> >
>> > if(n==0)
>> > return 0;
>> >
>> > jack_midi_event_t jev;
>> >
>> >
>> > if(verb == 1)
>> > printf("%i: Data arrived!\n", cnt);
>> >
>> > for(i = 0;i<n;i++){
>> >
>> > res = jack_midi_event_get(&jev,in_port_buf,i);
>> > if(res == 0){
>> > if(verb == 1){
>> > printf("Got event, %i bytes!\n",(int) jev.size);
>> > for(j=0;j<jev.size;j++)
>> > printf("%i: %i\n",j,jev.buffer[j]);
>> > }
>> > } else{
>> > if(verb == 1)
>> > printf("ERROR getting event!\n");
>> > return 0;
>> > }
>> >
>> >
>> > //transmit data
>> > cnt++;
>> > //buffer = jack_midi_event_reserve(port_buf, i, 3);
>> >
>> >
>> > //controll to MIDI channel 1!
>> > if(jev.buffer[0] == 176 && jev.buffer[1] == 97){
>> > if(verb == 1)
>> > printf("MUTE CONTROL CH1 sent\n");
>> > //first button: set mute register on channel 1
>> > //buffer[0] = 176;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 176;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> > else if(jev.buffer[0] == 176 && jev.buffer[1] == 96){
>> > if(verb == 1)
>> > printf("MUTE CONTROL to CH2 sent\n");
>> > //second button: set mute register on channel 2
>> > //buffer[0] = 177;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 177;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> > else if(jev.buffer[0] == 176 && jev.buffer[1] == 66){
>> > if(verb == 1)
>> > printf("MUTE CONTROL CH3 sent\n");
>> > //third button: set mute register on channel 3
>> > //buffer[0] = 176;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 178;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> > else if(jev.buffer[0] == 176 && jev.buffer[1] == 67){
>> > if(verb == 1)
>> > printf("MUTE CONTROL to CH4 sent\n");
>> > //fourth button: set mute register on channel 4
>> > //buffer[0] = 177;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 179;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> > else if(jev.buffer[0] == 176 && jev.buffer[1] == 64){
>> > if(verb == 1)
>> > printf("MUTE CONTROL to CH5 sent\n");
>> > //fifth button: set mute register on channel 5
>> > //buffer[0] = 177;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 180;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> > else if(jev.buffer[0] == 176 && jev.buffer[1] == 65){
>> > if(verb == 1)
>> > printf("MUTE CONTROL to CH6 sent\n");
>> > //sixth button: set mute register on channel 6
>> > //buffer[0] = 177;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 181;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> > else if(jev.buffer[0] == 176 && jev.buffer[1] == 7){
>> > if(verb == 1)
>> > printf("MUTE CONTROL to CH7 sent\n");
>> > //seventh button: set mute register on channel 7
>> > //buffer[0] = 177;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 182;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> > else if(jev.buffer[0] == 176 && jev.buffer[1] == 10){
>> > if(verb == 1)
>> > printf("MUTE CONTROL to CH8 sent\n");
>> > //eighth button: set mute register on channel 8
>> > //buffer[0] = 177;
>> > //buffer[1] = 7;
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = 183;
>> > jbuffer[1] = 7;
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> > }
>> >
>> >
>> >
>> >
>> > else if((jev.buffer[0]& 0xF0) == 128 || (jev.buffer[0]& 0xF0) ==
>> > 144){
>> > //note key, pass through
>> > if(verb == 1)
>> > printf("SOUND PASSED-THROUGH\n");
>> > //notes; let them pass
>> > //buffer[0] = jev.buffer[0];
>> > //buffer[1] = jev.buffer[1];
>> > //buffer[2] = jev.buffer[2];
>> > jbuffer[0] = jev.buffer[0]; //CH1
>> > jbuffer[1] = jev.buffer[1];
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time , jbuffer,
>> > 3);
>> > jbuffer[0] = jev.buffer[0] + 1; //CH2
>> > jbuffer[1] = jev.buffer[1];
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time , jbuffer,
>> > 3);
>> > jbuffer[0] = jev.buffer[0] + 2; //CH3
>> > jbuffer[1] = jev.buffer[1];
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time , jbuffer,
>> > 3);
>> > jbuffer[0] = jev.buffer[0] + 3; //CH4
>> > jbuffer[1] = jev.buffer[1];
>> > jbuffer[2] = jev.buffer[2];
>> > res = jack_midi_event_write(port_buf, jev.time , jbuffer,
>> > 3);
>> > }
>> >
>> > //res = jack_midi_event_write(port_buf, i, jev.buffer, 3);
>> > //res = jack_midi_event_write(port_buf, jev.time, jbuffer, 3);
>> >
>> >
>> > }
>> >
>> > return 0;
>> >
>> > }
>> >
>> >
>> >
>> > Jack-Devel mailing list
>> > [hidden]
>> > http://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org
>> >
>>
>>
>>
>> --
>>
>> http://www.openavproductions.com
>
>
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