[alsa-devel] Help with editing the Raw Midi data with ALSA?

[Ember Autumn Rose Leona]

Dear Clemens,

I just figured it out... Thank you... I had to use sudo
$sudo gcc -o keyflipd5 KeyFlip.c

Now I see it in aconnect. ^-^
You are kick awesome!! thank you!!!!
-Ember

On 9/8/13, Ember Autumn Rose Leona <emberleona at gmail.com> wrote:
> Thank you Clemens!
>
> You pretty much wrote it all for me, I made a minor edit so that it
> flips the keyboard on D5.
> I know that this should work... but I am getting compiler errors with
> undefined reference...
>
> here's the error: http://pastebin.com/41WAvjCs
>
> I even looked into the ld in /usr/bin/ which was a link to ld.bfd I
> redirected it to ld.gold... I still get errors. I already have the
> library libasound2-dev installed  and I even compiled from source
> cmake . then make  and put the all the /include/ files in the program
> directory....
>
> It must be something I am doing wrong... if you can help that would be
> nice.
> PS>$ pkg-config --libs alsa
> -lasound
>
> This is what I changed.
>
> if (snd_seq_ev_is_note_type(ev))
>                     if (ev->data.note.note < 125)
> ev->data.note.note = (((127 - (ev->data.note.note & 127)) - 3) & 127)
>
> I might end up using an array I think there will be less latency...
> The ANDs make sure that it is within the byte range  0-127 before and
> after... -3 is the offset for D5 -27 for D4 I am going to put these in
> an array. I want to allow the user to choose what note to mirror on.
>
> I have tried -lasound I even put the entire alsa lib in the project
> root and changed the .c file to include "asoundlib.h"
> include "seqmid.h"  //this is where most those macros and functions are
>
> Well, I really tried b4 bugging you again...
>
> Thanks for you help thus far,
> Ember
>
>
> On 9/7/13, Clemens Ladisch <clemens at ladisch.de> wrote:
>> Ember Autumn Rose Leona wrote:
>>> I just joined the mailing list on after being referred to it.
>>
>> Please note that, regardless of what others might say, this is the list
>> where you are most likely to get an answer.
>>
>>> Is it possible for me to edit the Raw Midi data with ALSA...
>>
>> It would be possible to write your own tool that does the editing.
>>
>>> What I want to do is edit the Midi Messages, re-mapping the notes. I
>>> simply
>>> want to flip the progression of the keys on a midi piano from high
>>> notes to low notes.
>>
>> See the example program below.  It modifies MIDI messages received at
>> its input ports and re-sends them from its output port.  Insert it into
>> your routing like this:
>>
>>   Keyboard  -->  KeyFlip  -->  Synth
>>
>> (Use aconnect to make the connections.)
>>
>>
>> Regards,
>> Clemens
>>
>> --8<---------------------------------------------------------------->8--
>>
>> #include <stdio.h>
>> #include <stdlib.h>
>> #include <alsa/asoundlib.h>
>>
>> #define CHECK(fn) check((fn), #fn)
>> static void check(int err, const char *fn)
>> {
>> 	if (err < 0) {
>> 		fprintf(stderr, "%s failed: %s\n", fn, snd_strerror(err));
>> 		exit(EXIT_FAILURE);
>> 	}
>> }
>>
>> int main(void)
>> {
>> 	snd_seq_t *seq;
>>
>> 	/* create I/O ports */
>> 	CHECK(snd_seq_open(&seq, "default", SND_SEQ_OPEN_DUPLEX, 0));
>> 	CHECK(snd_seq_set_client_name(seq, "Keyboard Flipper"));
>> 	CHECK(snd_seq_create_simple_port(seq, "KeyFlip",
>> 					 SND_SEQ_PORT_CAP_READ |
>> 					 SND_SEQ_PORT_CAP_WRITE |
>> 					 SND_SEQ_PORT_CAP_DUPLEX |
>> 					 SND_SEQ_PORT_CAP_SUBS_READ |
>> 					 SND_SEQ_PORT_CAP_SUBS_WRITE,
>> 					 SND_SEQ_PORT_TYPE_MIDI_GENERIC |
>> 					 SND_SEQ_PORT_TYPE_SOFTWARE |
>> 					 SND_SEQ_PORT_TYPE_APPLICATION));
>>
>> 	for (;;) {
>> 		snd_seq_event_t *ev;
>> 		int err;
>>
>> 		/* read one event from the input port */
>> 		err = snd_seq_event_input(seq, &ev);
>> 		if (err == -ENOSPC)
>> 			continue;
>> 		CHECK(err);
>>
>> 		/* modify the note value */
>> 		if (snd_seq_ev_is_note_type(ev))
>> 			ev->data.note.note = 127 - (ev->data.note.note & 127);
>>
>> 		/* send the event from the output port */
>> 		snd_seq_ev_set_subs(ev);
>> 		snd_seq_ev_set_source(ev, 0);
>> 		snd_seq_ev_set_direct(ev);
>> 		CHECK(snd_seq_event_output_direct(seq, ev));
>> 	}
>> }
>>
>