Bc2000 (for the BCF2000 & BCR2000)

--- In bc2000@yahoogroups.com, "ashasha3" <ashasha3@...> wrote:
> I'm trying to get to the bottom of a buffer underflow issue.  I can
> get the data to pass from my device to the PC properly using a
> MidiSport 2x2.
[]
> This is the exact same command running through the BCF2000:
[]
> Now I know that's a lot of numbers to dig through, but the jist of
> all of this is that it doesn't match up at all.
> Any idea of what the heck is going on?

I think this is a bug in the BCF2000 (and the BCR2000).
I encountered this bug one or two years ago. I'm still planning to get to the bottom of this and write a report in my "BC MIDI Implementation.pdf", but haven't got round to this yet.

If I remember my tentative conclusions correctly, this is roughly what happens:

Whenever the BCF2000 passes on a long SysEx message from an input port to an output port, it swallows 3 bytes after every 1020 (or so) bytes.

If this is true, in your case (a single message of 2060 bytes) two sequences of three bytes should get swallowed, leaving you with 6 bytes less: indeed exactly what your output shows.

This bug definitely occurs for USB-based MIDI outputs; but I'm not sure about the "standard" MIDI ports.

The only "solution" is to avoid sending messages larger than 1020 bytes via the BCF2000/BCR2000 (or at least via a USB-based MIDI output port).

Best wishes,
Mark van den Berg.