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Re: Draft Updated Charter adding Mouse Lock and Gamepad

From: Chris Wilson <cwilso@google.com>
Date: Tue, 4 Oct 2011 14:06:21 -0700
Message-ID: <CAJK2wqX9U2o=v66ka+7LuAbe+1OXwGYt8MAUyasekhXJkr2MXA@mail.gmail.com>
To: public-webevents@w3.org
I'd been talking with a variety of people about the need for a Music
Controller API - i.e. MIDI input/output, so I can synchronize music apps, as
well as interface my physical keyboard controllers, synthesizers and drum
machines with the web platform.  After some thought, I'd like to propose
that Music Device Communication be added to the Web Events charter - I
believe the challenges of this API are quite similar to the Gamepad API
(different API, but the same general kind of patterns, and heavily
event-based). This would be the web platform's analog to CoreMIDI on
MacOS/iOS, or the Windows MIDI API. Proposed charter text would read
something like this:
Music Device Communication

Some user agents have connected music devices, such as synthesizers,
keyboard controllers and drum machines.  The widely adopted MIDI
protocol enables electronic musical instruments, controllers and computers
to communicate and synchronize with each other. MIDI does not transmit audio
signals: instead, it sends event messages about musical notes, controller
signals for parameters such as volume, vibrato and panning, cues and clock
signals to set the tempo, and system-specific MIDI communications (e.g. to
remotely store synthesizer-specific patch data).
This deliverable defines API support for the MIDI protocol and common music
device scenarios in the web platform.

--------------

Some background why I think it belongs in the Events WG rather than the
Audio WG:
MIDI is actually very much like game controllers in terms of being entirely
event-based, and fundamentally being a model of sending uni-directional
controller messages back and forth between devices.  In fact, Microsoft's
Sidewinder Force Feedback Pro joystick (I still have one somewhere in my
basement, I think -http://en.wikipedia.org
/wiki/Microsoft_SideWinder#Joystick) - actually utilized the MIDI break-out
pins of the typical analog game port (http://en.wikipedia.org
/wiki/Game_port#MIDI_connectors) on the sound card as a channel for digital
data.

The significant challenges inherent in the Audio API - the sample-accurate
scheduled playback model, the convolution engine and other "inline effects"
- don't apply at all to a MIDI API, and there's not much in the way of
shared concepts between audio and MIDI devices themselves (many audio
adapters implement a MIDI port too, but it shows up as a completely separate
device in MacOS/Windows).  MIDI is a very event-based protocol (I've written
a bunch of MIDI software in the distant past, down to implementing a MIDI
driver) - there's no scheduling, so you need to deliver events as they
arrive.  (A millisecond here or there in MIDI isn't a big deal, whereas in
audio gaps like that wouldn't be acceptable.)

A MIDI API, on the other hand, would (I expect) have some music-specific
APIs (e.g. NoteOn()/NoteOff() kinda stuff), but mostly it's about plugging
in event handlers for note on/off and continuous controller messages (and
sending the same kinds of messages out, of course), as well as the
configuration system for "which MIDI port should I use".  Those all seem
like symmetric problems with the other Events APIs, particularly the Game
Controller API.  If I didn't feel like the music controller API should have
some music-specific APIs (e.g. the aforementioned noteon/off), I'd actually
say it's just a slightly different game controller.  MIDI may be frequently
used in conjunction with the Web Audio API in an actual app, but the use
cases, scenarios and requirements are pretty different.

Obviously, I'd volunteer to edit (though I'm not tied to doing so either).
 If others feel this fits better elsewhere, please give me an idea where.

Thanks!
-Chris

From: Arthur Barstow <art.barstow@nokia.com>
Date: Tue, 27 Sep 2011 12:24:31 -0400
Message-ID: <4E81F8BF.1040507@nokia.com>
To: ext Doug Schepers <schepers@w3.org>, public-webevents@w3.org

Doug - thanks; this looks good to me.

All - if you have any comments, please send them to public-webents as
soon as possible.

On 9/27/11 10:48 AM, ext Doug Schepers wrote:
> Hi, Folks-
>
> I have made a first draft of a proposed WebEvents charter revision to
> add the Mouse Lock API and Gamepad API specs.
>
>   http://www.w3.org/2010/webevents/charter/2011/Overview.html
>
> I made minimal changes to bring these specs into scope, which should
> make an easy AC review.
>
> Please review the draft charter and let me know what you think.
>
> Regards-
> -Doug Schepers
> W3C Developer Outreach
> Project Coordinator, SVG, WebApps, Touch Events, and Audio WGs
>
Received on Tuesday, 4 October 2011 21:07:02 UTC

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