The AMT8 have a similar system to reduce the timing errors. In fact the sequencer device in the midi windows API does have a similar scheme: you send blocks of data in which every midi message is time stamped. I imagine the driver does the clock translation for you.
Sebastien ----- Original Message ----- From: "martijn sipkema" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, December 21, 2001 12:15 PM Subject: Re: [linux-audio-dev] Introducing DMIDI > > > I agree. The idea of combining messages into a packet might > > > be interesting > > > when the source of the MIDI stream is a sequencer application instead > > > of a human playing on a MIDI keyboard. Here MIDI events can be known > > > ahead of time and could be sent in in bursts and the MIDI > > > stream is often > > > less sparse when coming from a sequencer. > > > > You can't still do anything with the MIDI bytes before you get the last > one! > > With MWPP there are always complete MIDI messages in a packet, not > just MIDI stream bytes. It doesn't support an arbitrary MIDI stream. > > > So it makes sense to put MIDI event(s) into a packet, but it shouldn't be > > restricted to one MIDI event / packet as it's not efficent. Put there > either > > one (human player, or if he /she is so superfast then put as many as > he/she > > can play) or as many as can fit (computer player) as use some reasonable > and > > standard way for timestamping. In this case it could be the LTB (Linear > > Time Base MIDI Time Stamping method, see > > > > > http://www.steinberg.net/infocenter/discoveries/lineartimebase/index.phtml?s > > id=06023461 > > A delta-time (with respect to the RTP packet timestamp) can be used for > multiple events in the MIDI payload, as was already said. > > The link to steinberg's LTB experiment doesn't say anything about how the > protocol works, but even if it did, LTB is a proprietary protocol for > communication between a computer and a MIDI interface over a serial > connection (USB), so it hardly has anything to do with MWPP. > > The way LTB works as I read it in the german KEYS magazine is that the > MIDI interface has it's own clock and the computer sends timestamped > messages to the interface which the interface uses to adjust its clock. The > interface schedules MIDI events it received from the computer using this > clock. Anyway, I have an Emagic AMT8 MIDI interface :) > > --martijn > >
