$NCDId: @(#)actions,v 1.1 1994/05/26 16:19:20 greg Exp $
To: kurz@cenatls.cena.dgac.fr (Gregory KURZ)
cc: netaudio@ncd.com
Subject: Re: buckets
In-reply-to: Your message of "Fri, 18 Mar 94 18:52:22 GMT."
<9403181852.AA00846@verso.cena.dgac.fr>
Date: Fri, 18 Mar 94 11:05:31 PST
From: Greg Renda <greg@hansen.ncd.com>
kurz@cenatls.cena.dgac.fr (Gregory KURZ) writes:
> I'm studying real-time sound synthesis and I would like to use
> buckets in order to decrease the working time of my program (it's
> better to let the server deal with the samples when they're ready to
> be played). I've tried to do the following thing :
>
> _ storing the first sample-table in a bucket
> _ asking the server to play from the bucket (AuSoundPlayFromBucket)
> _ storing the second sample-table in another bucket (while the first
> one is being played)
> - asking the server to play from the second bucket as soon
> as the first one is finished (with the "done" callback)
> and so on...
>
> The problem is that between two different requests of playing, there's a 1/2
> second blank which is quite annoying for the real-time effect. Since the goal
> was to compute a continuous sound, I've also tried to store in a Bucket a
> single sample-table which would produce a nice sound if it was played
> continuosly (using the parameter Count in AuSoundPlayFromBucket), but that
> changes nothing.
>
> So, at last, my quesion is : is it possible to establish a kind of "link"
> between two buckets, so that one can be immediatly used after the other ?
You betcha! You want to use the "actions" feature. When creating a
component element (an import or an export) you can specify actions
that occur whenever the element changes state. An action can change
the state of another element, send a notify event, or do nothing
(useful for overriding the default actions). All actions contain:
- a trigger state, previous state, and reason
This says when the action is to be triggered. For
example, if you want the action to be triggered when
the element changed from started to paused due to some
user interaction you'd set:
trigger state = AuStatePause
previous state = AuStateStart
reason = AuReasonUser
A ChangeStateAction also contains:
- the flow id containing the element to perform the state change on.
- the element number in the flow to perform the state change
on. This may be AuElementAll to change the state of all the
elements in the specified flow.
- the new state for the element.
Legal states are:
AuStateStop
AuStateStart
AuStatePause
AuStateAny (used only for a trigger or previous state match)
Legal reasons are:
AuReasonUser a client interaction
AuReasonUnderrun the element ran out of data unexpectedly
AuReasonOverrun the element overran its buffer
AuReasonEOF the element reached the end of its data
AuReasonWatermark the element's buffer reached a watermark
AuReasonHardware some hardware problem (perhaps it can't keep up)
AuReasonAny any of the above
Note that when you specify actions for an element, you are overriding
any default actions that the element might have. So if you want any
of those default actions to occur in addition to your own actions, you
have to specify them in the action list. Here are the default actions
for each component element:
Component Action Trigger Prev Reason Flow Element State
--------------- --------------- ------- ------- ------- ------- ------- -----
ImportClient SendNotify Pause Any Any
" SendNotify Stop Any Any
" ChangeState Pause Any Any Own All Pause
" ChangeState Start Pause Any Own All Start
" ChangeState Stop Any Any Own All Stop
ImportDevice (None)
ImportBucket SendNotify Pause Any Any
" SendNotify Stop Any Any
" ChangeState Stop Any Any Own All Stop
ImportWaveForm SendNotify Pause Any Any
" SendNotify Stop Any Any
" ChangeState Stop Any Any Own All Stop
ExportClient SendNotify Pause Any Any
" SendNotify Stop Any Any
" ChangeState Pause Any Any Own All Pause
" ChangeState Start Pause Any Own All Start
" ChangeState Stop Any Any Own All Stop
ExportDevice (None)
ExportBucket SendNotify Pause Any Any
" SendNotify Stop Any Any
" ChangeState Stop Any Any Own All Stop
ExportMonitor (None)
For examples of using actions, see audial and auphone. auphone uses
an action to contiuously play the ringing and busy sounds.
The catch to all of this is that you'll have to use the lower level
API calls for your client since the higher level calls don't support
actions. Again, see the sample clients for examples.
-Greg
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