On Sat, Oct 13, 2001 at 06:22:41AM -0500, dave willis wrote: > Windows 98 or 2000" (from usb8x8.pdf). anyway, i don't think serial is > fast enough for 8 midi ports (educated guess). what would be wrong with > usb?
Well, it depends. One thing about MIDI is that it's extremely bursty, and so getting good performance isn't as much a matter of raw bandwidth as it is latency. Most of the time, MIDI cables are idle; and for a running song, only a small percentage of the total bandwidth is in use. The exception is continuous controller data, which does tend to come in thick streams, but even then they're lighter than the tremendous bursts that occur in most Western music. This is where USB fails. The real problem with USB is that it's a monarch system, and essentially unidirectional; all transactions must be initiated by the host. This isn't so much a problem for output - you can get pretty good latency there - but for input it's a real problem, because when bytes show up at an external MIDI interface, the interface can't do anything with them until the host asks it for them: USB input is entirely polled, and the minimum granularity is around 4 mS - not too good. So in some situations, an async serial link can actually _outperform_ a USB link. -- Michael Ashton <[EMAIL PROTECTED]> ---- Pray for: - the souls of those who have lost, and will lose, their lives, as a result of the US terrorist attacks; - the souls of those responsible, that they may see the destruction they have wrought, and repent, before it is too late; - the United States, that its people will return to God for strength, and forgive; for the attackers "know not what they do"; - the agents of justice on Earth, that they may speedily do God's will, whatever that may be. _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
