[gmpi] Re: Parameters / controls / GMPI event system - refreshment
- From: thockin@xxxxxxxxxx
- To: gmpi@xxxxxxxxxxxxx
- Date: Wed, 30 Nov 2005 17:34:46 -0800
On Thu, Dec 01, 2005 at 01:53:50PM +1300, Jeff McClintock wrote:
> >We (XAP folk) had previously
> >described it like this:
> >
> ....... The plugin notifies the host
> >that VVID(v) is now in state VVID_DONE.
>
> Hi,
> This is *far* too complicated. Any system requiring the plugin send
> info back upsteam is flawed.
I disagree - it's very simple. The only thing the plugin has to do is
tell the host when's release phase is done, and you know - even that is
not needed.
see below
> What is the mistake in the following *super* simple VVID allocation scheme?
>
> KEYBOARD controllers:
> Assign each key a unique voice ID.
>
> - uses a finite number of voice-IDs
> - Host has no active role in physical voice allocation.
> - voice ID's are only re-used to play the same note a second (or third)
> time, never to play an unrelated note.
I want to be able to play C4 8 times at the same timestamp, and control
the per-voice parameters of each instance independantly.
A slightly modified VVID state machine could be simple enough:
All VVIDs start in state VVID_NULL (non-existant).
The host tells the plugin to allocate VVID(v). VVID(v) is now in state
VVID_IDLE.
-> The host can send events to VVID(v) in preparation to turn that
voice on.
-> The plugin is not generating sound for this voice.
The host activates VVID(v). VVID(v) is now in state VVID_ACTIVE.
-> The plugin allocates a real voice for VVID(v).
-> The host can send events to VVID(v) to modify it's continuous
per-voice controls.
The host stops VVID(v). VVID(v) is now in state VVID_RELEASE.
-> The host can send events to VVID(v) to modify it's continuous
per-voice controls.
The host tells the plugin to deallocate VVID(v). The VVID is in state
VVID_NULL (non-existant).
-> The host can no longer send events to VVID(v).
Notice the lack of any plugin->host communication. The
allocate/deallocate process is a way for the host to indicate it's
interest in a VVID. Once the host deallocates that VVID, it is saying "I
will not send any more events for this VVID". If the plugin is still
playing the actual voice associated with VVID(v), it can continue to play
it, and no more events will be delivered for it.
In fact, the deallocate is not really NEEDED. If you allocate a VVID that
is already allocated, you can consider that a de-allocation. IF we went
with this model, this would be a decisionof cleanliness and convenience.
Tim
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