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@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@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));

} }