>> "Some keyboard instruments implement release velocity
>> where a Note-Off code accompanied by a 'velocity off'
>> byte is used. A receiver must be capable of recognizing
>> either method of turning off a note, *and should
>> treat them identically.*" (emphasis added)
>
>"should treat them identically" should be interpreted as : "a noteon with
vel
>0 should be treated identically as a noteoff with vel 64" imo.
Yes, I agree. But there is no hint of giving any semantics
for this byte and the section on velocity does not mention
it at all. I have just sent a note to the MIDI spec people
asking for a note clarifying this from their point of view.
>In this case, why the hell did you implement noteon velocity ? Couldn't it
>have been done likewise with a controller ? ;-) No of course it couldn't,
>because a controller is a channel message (the same for all notes at any
given
>time) whereas velocity (whether on or off) is a part (important imo) of a
note
>message, ie it can be different for two notes pressed (or released)
simultaneously.
You could use poly aftertouch if you like. In any case, noteon velocity has
important, useful semantics in MIDI which need to be preserved. This is
not the case for noteoff (can you give me an example of what I should
reasonably expect from a device as a content author when I send it noteoff
velocities? Is there content that makes important use of noteoff velocity?)
>Moreover the absence of noteoff velocity is a blatant exception : it's the
>only feature of MIDI channel messages which is lost in SAOL.
That's not exactly true -- many of the GM controller semantics and
the Omni commands have been lost, to avoid burdening the SAOL spec by
making it try to act like a GM device in all cases. MIDI semantics
are provided in SAOL as a convenience and for ease of porting (note,
not "using") existing content to MPEG-4. But MIDI is not the
primary control language in MPEG-4 and in the long run we'll gain
more by moving away from MIDI than by trying to strictly preserve
backward compatibility (particularly for the marginal aspects of
MIDI like noteoff velocity) in all things.
The upshot is, if you want fancy control over SAOL, use SASL. That's
what it's for.
>In conclusion I share the common conception (you can hardly call it
>misconception, as I said above) that noteoff velocity is a useful and
>expressive feature. However I realize that it may be a bit late to express
>such an opinion, I can only hope that a future version of SAOL will correct
this.
Please don't misunderstand--I am archiving all concerns that are
articulated about SAOL structure and function so that when it
comes time to think about corrigenda or additions to the standard,
they can all be discussed and considered fully. So I'm not
ignoring or dismissing your complaints at all (after all, I'm not
the owner of SAOL, ISO is), just trying to articulate why the
decisions that were made, were made.
Best,
-- Eric
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| Eric Scheirer |A-7b5 D7b9|G-7 C7|Cb C-7b5 F7#9|Bb |B-7 E7|
|eds@media.mit.edu| < http://sound.media.mit.edu/~eds >
| 617 253 0112 |A A/G# F#-7 F#-/E|Eb-7b5 D7b5|Db|C7b5 B7b5|Bb|
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