problems with allegro's midi

problems with allegro's midi

Mark Oates

Member #1,146

March 2001

I'm writing a sequencer and I'm using allegro's midi routines. Each time I start the program, allegro (or something) throws out midi messages to all 16 channels to set their respective volumes to 0. So I wrote this simple program:

1#include <allegro.h>
2 
3void note_on(int channel, int pitch, int vel)
4{
5   unsigned char msg[3];
6 
7   msg[0] = 0x90+channel;
8   msg[1] = pitch;
9   msg[2] = vel / 2;
10 
11   midi_out(msg, 3);
12}
13 
14 
15void main()
16{
17     allegro_init();
18     
19     install_sound(DIGI_NONE, MIDI_AUTODETECT, NULL);
20     
21     note_on(0, 60, 64);
22     
23} END_OF_MAIN();

and the output of my sampler (Gigastudio) shows the following messages are sent to it once I run the program:

1 
2Time
3Stamp   Port   Chan    Event        Data 1      Data 2    Flags
4============================================================================================== 
572649  1  1  Note On      C3      32 (velocity)  0x0  
672649  1  1  Controller Change  7 Channel Volume (7)  0    0x0  
772649  1  2  Controller Change  7 Channel Volume (7)  0    0x0  
872649  1  3  Controller Change  7 Channel Volume (7)  0    0x0  
972649  1  4  Controller Change  7 Channel Volume (7)  0    0x0  
1072649  1  5  Controller Change  7 Channel Volume (7)  0    0x0  
1172649  1  6  Controller Change  7 Channel Volume (7)  0    0x0  
1272649  1  7  Controller Change  7 Channel Volume (7)  0    0x0  
1372649  1  8  Controller Change  7 Channel Volume (7)  0    0x0  
1472649  1  9  Controller Change  7 Channel Volume (7)  0    0x0  
1572649  1  10  Controller Change  7 Channel Volume (7)  0    0x0  
1672649  1  11  Controller Change  7 Channel Volume (7)  0    0x0  
1772649  1  12  Controller Change  7 Channel Volume (7)  0    0x0  
1872649  1  13  Controller Change  7 Channel Volume (7)  0    0x0  
1972649  1  14  Controller Change  7 Channel Volume (7)  0    0x0  
2072649  1  15  Controller Change  7 Channel Volume (7)  0    0x0  
2172649  1  16  Controller Change  7 Channel Volume (7)  0    0x0  
2272649  1  1  Controller Change  All Notes Off (123)  0    0x0  
2372649  1  1  Controller Change  All Sounds Off (120)  0    0x0  
2472649  1  2  Controller Change  All Notes Off (123)  0    0x0  
2572649  1  2  Controller Change  All Sounds Off (120)  0    0x0  
2672649  1  3  Controller Change  All Notes Off (123)  0    0x0  
2772649  1  3  Controller Change  All Sounds Off (120)  0    0x0  
2872649  1  4  Controller Change  All Notes Off (123)  0    0x0  
2972649  1  4  Controller Change  All Sounds Off (120)  0    0x0  
3072649  1  5  Controller Change  All Notes Off (123)  0    0x0  
3172649  1  5  Controller Change  All Sounds Off (120)  0    0x0  
3272649  1  6  Controller Change  All Notes Off (123)  0    0x0  
33 
34Time
35Stamp   Port   Chan    Event        Data 1      Data 2    Flags
36============================================================================================== 
3772649  1  6  Controller Change  All Sounds Off (120)  0    0x0  
3872649  1  7  Controller Change  All Notes Off (123)  0    0x0  
3972649  1  7  Controller Change  All Sounds Off (120)  0    0x0  
4072649  1  8  Controller Change  All Notes Off (123)  0    0x0  
4172649  1  8  Controller Change  All Sounds Off (120)  0    0x0  
4272649  1  9  Controller Change  All Notes Off (123)  0    0x0  
4372649  1  9  Controller Change  All Sounds Off (120)  0    0x0  
4472649  1  10  Controller Change  All Notes Off (123)  0    0x0  
4572649  1  10  Controller Change  All Sounds Off (120)  0    0x0  
4672649  1  11  Controller Change  All Notes Off (123)  0    0x0  
4772649  1  11  Controller Change  All Sounds Off (120)  0    0x0  
4872649  1  12  Controller Change  All Notes Off (123)  0    0x0  
4972649  1  12  Controller Change  All Sounds Off (120)  0    0x0  
5072649  1  13  Controller Change  All Notes Off (123)  0    0x0  
5172649  1  13  Controller Change  All Sounds Off (120)  0    0x0  
5272649  1  14  Controller Change  All Notes Off (123)  0    0x0  
5372649  1  14  Controller Change  All Sounds Off (120)  0    0x0  
5472649  1  15  Controller Change  All Notes Off (123)  0    0x0  
5572649  1  15  Controller Change  All Sounds Off (120)  0    0x0  
5672649  1  16  Controller Change  All Notes Off (123)  0    0x0  
5772649  1  16  Controller Change  All Sounds Off (120)  0    0x0

It seems to make sense that the "all notes off" commands come as the program is closing, but what's with the volume changes?

In my sequencer program, I noticed that the vol changes are only sent after the first midi message is sent, not when it does the install_sound().

does anybody know what might be causing this?

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