[Jsynthlib-devel] Signal Errors on Mac OSX

[Jeff W. <jww...@ya...>]

Just a note Mac OSX signal errors. I tried Plumstone
but was unable to get it working. However I did some
experimentation with CAProvider yesterday and
discovered a couple of modifications to the
core.MidiUtil.java class that will at least cut down
on the frequency of signal errors. First of all, I was
having a lot of problems with the Behringer FCB1010.
This device only has one type of patch with a length
of 2352. Since it's a fairly large patch and since I
wasn't getting as many signal errors as with the other
devices, I suspected that the problem might be some
kind of a timing issue.

First, I changed the value of BUFSIZE from 0 to 256
which causes the MIDI data to be sent in multiple
blocks of 256 bytes. Then I added a 100 millisecond
delay at the end of the send(Receiver rcv, MidiMessage
msg) method. The whole thing looks like this:
    /**
     * MIDI Output buffer size.  If set to '0', Whole
Sysex data is
     * sent in one packet.  Set '0' unless you have
problem.
     */
    private static final int BUFSIZE = 256;

    /**
     * Send a <code>MidiMessage</code>.  If BUFSIZE is
non-zero, data
     * size will be limited to the size.
     */
    public static void send(Receiver rcv, MidiMessage
msg)
        throws MidiUnavailableException,
InvalidMidiDataException {
            int size = msg.getLength();
            
            if (BUFSIZE == 0 || size <= BUFSIZE) {
                rcv.send(msg, -1);
                log("XMIT: ", msg);
            } else {
                // divide large System Exclusive
Message into multiple
                // small messages.
                byte[] sysex = msg.getMessage();
                byte[] tmpArray = new byte[BUFSIZE +
1];
                for (int i = 0; size > 0; i +=
BUFSIZE, size -= BUFSIZE) {
                    int s = Math.min(size, BUFSIZE);
                    
                    if (i == 0) {
                        System.arraycopy(sysex, i,
tmpArray, 0, s);
                        ((SysexMessage)
msg).setMessage(tmpArray, s);
                    } else {
                        tmpArray[0] = (byte)
SysexMessage.SPECIAL_SYSTEM_EXCLUSIVE;
                        System.arraycopy(sysex, i,
tmpArray, 1, s);
                        ((SysexMessage)
msg).setMessage(tmpArray, ++s);
                    }
                    rcv.send(msg, -1);
                    log("XMIT: ", msg);
                    try {
                        Thread.sleep (100);
                    } catch (Exception e) {}
                }
            }
        }

I realize this is only a temporary workaround. While
it doesn't totally eliminate signal errors I'm getting
way fewer of them than I was getting.

I have only made these changes to my local copy and I
don't plan on committing the changes, since they would
only apply to Mac users and would only be a temporary
workaround at best. But for any of you who are Mac
users and don't want to use Plumstone, this might be
another alternative.



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