Re: Questions on data in MIDIPackets
Re: Questions on data in MIDIPackets
- Subject: Re: Questions on data in MIDIPackets
- From: Brian Willoughby <email@hidden>
- Date: Mon, 11 Feb 2002 16:11:37 -0800
Herbie Robinson <email@hidden> wrote:
[ I already added a bug asking for clarification as to whether the
[ time-stamp applies to the beginning or the end of the packet. If
[ no clarification ever comes, then I would assume the time-stamp
[ applies to the END of the packet (i.e. the instant the last byte
[ has finished transmitting), because that's when any real hardware
[ will be able to start responding to the last event in the packet.
I have to disagree for a couple of reasons:
First of all, I can think of a few examples where a MIDI device can either
completely or at least partially respond to a message before all bytes have
arrived - e.g. a Note Off event directed to a voice which does not respond to
Note-off Velocity could easily respond to the message before the third byte
arrives. It's true that the simplest MIDI firmware might wait for all bytes
before starting to respond, but more aggressive devices could get very creative
about responding earlier to specific types of messages - and therefore the
timing of the beginning of the packet should be the focus.
More importantly, the timing of the beginning of the packet more closely
correlates to a physical event, while the end of the packet is merely an
artifact of the transmission medium, and will vary from interface to interface.
Most MIDI events originate from a Human Interface Device, and so the
time-stamp of the beginning of the packet most closely reflects the real event.
Most musicians probably don't care about preserving the latency introduced by
multi-byte packets on traditional MIDI, and sequencers certainly shouldn't
preserve (slow) MIDI timings when playing back on higher resolution interfaces
such as USB.
Brian Willoughby
Sound Consulting
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.