midi programing in C: sysex-problem

Miscellaneous
1

Hi,

i don´t know if anybody in here already did some

Midi programing in C?  (serge?) :wink:

we´ve got a problem with receiving sysex-messages. to receive a sysex message you have to call the method “midiInAddBuffer” to provice a buffer where the sysex-data can be stored in. you have to call it for every package of the message.

this works great so far - but the problem is if i close the Indevice now and try to open it again it crashes.

if i call “midiInAddBuffer” only once at the beginning, i can reveive only the first package for sure, but now i can close and open the device without any problems.

has anyone an idea what we do wrong?

thanks

tazumi

2

which API are you using?

Copy/paste the source code here :wink:

3

We’re using the standard Windows midi api.

I do not have the source code here, so I will try to explain what I do in the code.

I open a midi device with the midiInOpen function. I also defined a callback function, where I can receive the messages.

After opening the device I start the receiving with midiInStart and add a buffer with midiInAddBuffer.

Before adding the buffer I prepare it with midiInPrepareHeader. It all works fine. Now I can receive SysEx messages (and other midi messages).

But only the first block. To receive more than one block I make another call of midiInAddBuffer in the callback function (after I received a block). Now I can receive all the other blocks, too.

But the device doesn’t close (midiInClose) right now and I cannot open it anymore. Do I have to do something else, before calling the second time midiInAddBuffer.

I will post the source code as soon as possible.

4

Everything you did looks okay. Now use the complimentary midiInUnprepareHeader() too. Always unprepare before using each sysex and before closing.

Initialize:

  • open with midiInOpen() using callback function

  • prepare with midiInPrepareHeader() for next sysex

  • buffer with midiInAddBuffer() for next sysex

  • start with midiInStart()

In callback function:

  • unprepare with midiInUnprepareHeader() old sysex

  • analyze or use the sysex data retrieved

  • prepare with midiInPrepareHeader() for next sysex

  • buffer with midiInAddBuffer() for next sysex

  • exit

When closing application:

  • stop with midiInStop()

  • reset with midiInReset()

  • unprepare with midiInUnprepareHeader() old sysex

  • close with midiInClose()

Something like this helped me in windows c programming. This was extracted from my more complicated code so forgive any errors in the suggestions.

5

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