mail from tim thompson:

From: "Tim Thompson" <###@###.###>
To: <###@###.###>
Cc: "Michael Bundschuh" <Michael.Bundschuh@Eng>
Subject: feedback on Java Sound API
Date: Thu, 24 Dec 1998 22:11:07 -0800
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Hi,
      I'm evaluating the Java Sound API - specifically
the MIDI parts. I'm trying to use the Java Sound API to
replace the native methods I've used for MIDI I/O.
In order to get the scheduling service
I need, I'm using the SequencePlayer, and writing
individual Buffers (with MidiMessages) to it.
(I don't want to just play a MIDI File, I want to do
interactive MIDI.)

The ability to schedule individual messages (with
TimeStamp info) is what I need, and it looks like the
write() method of SequencePlayer provides this capability.

First, the values I have to give to Buffer.setTimeStamp()
seem very high - it says they should be ticks, but I have
to give it a value of 2500000 to get any delay at all.
is it microseconds?

The main problem I have is that it appears as if the
write() method of SequencePlayer inserts the messages
into a list, and assumes that they are being written in
monotonically-increasing-TimeStamp order.
Therefore if I I do a write() of Buffers with timestamps of:

   a note-on message with timestamp 0
   a note-off message with timestamp 2500000
   a note-on message with timestamp 0
   a note-off message with timestamp 2500000

the third message will not get sent until after the second
message is sent.

Is this the intended behaviour of SequencePlayer.write()?

If so, it's usefulness is very limited for interactive MIDI things.
It's close, though - all it needs to do is an insertion sort
on the messages it is given. This only needs to be done if
the message's timestamp is less than the last message in
the current list - otherwise it can be added to the end (as I
assume it's currently doing). So, only applications that
actually need this scheduling feature will suffer any sorting
overhead. (the only overhead for all applications will be the
need for SequencePlayer to maintain
the "last message timestamp"). Applications that
use the load(MediaStream) method won't be affected,
and Applications that use DirectPlayer won't be affected either.

Basically I want the ability to schedule individual MIDI
messages independently. In order to do this, do I have
to create a separate SequencerPlayer for every message?
In the applications I want to consider, it is not possible
to determine everything beforehand - it's all generated
on-the-fly. Let me know what you think the best method
is to get independently-scheduled individual MIDI messages.

Thanks, and congratulations on the first release of the
Java Sound API - I'm looking forward to the things people
(including me) develop with it.

     ...Tim ###@###.###...