On Fri, Nov 21, 2008 at 12:34:17PM -0800, Albert Santoni wrote: > A quick calculation here shows a possible source of the problem: > The MIDI baud rate is 38400 bps, and if each MIDI LED command is 16- > bits, and is being sent 1000 times/second (1ms latency), then that > uses up about half of the MIDI bandwidth we have.
For anyone attempting detailed calculations on this... According to http://www.srm.com/qtma/davidsmidispec.html the MIDI baud rate is actually 31250bps +/- 1%, and the protocol has each byte sent as 1 start bit, 8 data bits, and one stop bit. Thus, each data byte takes 10 serial bits, and is sent in 320 microseconds. In other words, a "16-bit message" actually requires 20 bits on the serial line, for which 0.64ms should be allowed. Some MIDI messages are 3 bytes so you might need upto 0.96ms between those. So in theory something sending every 1ms, even on only one channel, could be using up almost the entire bandwidth. Ben ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Mixxx-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mixxx-devel
