EnvGen with doneAction 14 - unexpected behaviour.

[miguel-negrao]

(
x = SynthDef(\test, {

    var env = Env([ 1, 0 ],[ 6 ], \lin );

    EnvGen.kr(env, \gate.kr(0), doneAction:2).poll

}).play
)

This will post 1 indefinitely, while

(
x = SynthDef(\test, {

    var env = Env([ 1, 0 ],[ 6 ], \lin );

    EnvGen.kr(env, \gate.kr(0), doneAction:14).poll

}).play
)

frees the synth immediately after the first control bloc. The expected behaviour would be to behave the same as with doneAction 0-13 and just keep posting 1 indefinitely.

This seems like a bug, no ?

[telephon]

Not sure if this is in DoneAction (see SC_Node.cpp). Maybe it is in EnvGen, but I don't see where.

The behavior appears to be different in Linen

(
x = SynthDef(\test, {

    Linen.kr(\gate.kr(0), doneAction:14).poll

}).play
)
x.set(\gate, 1);

[telephon]

In the method: void EnvGen_Ctor(EnvGen *unit), there is an initialization of the current stage of the envelope to a very large integer:

unit->m_stage = 1000000000;

This appears to be overridden in cases where gate = 1. But if gate remains 0, the value is counted up from 1000000000, or stays the same.

In EnvGen_nextSegment, there is a test whether the envelope has overrun:

if (unit->m_stage+1 >= numstages) { // num stages

this is called immediately in our case.

By contrast, in Linen, where this problem doesn't exist, the default is different: unit->m_stage = 4;.

[telephon]

I've tried to escape the above initialization case, and eventually gave up, because I don't really know what the behavior should be before the gate has been triggered: what value should the UGen return?.

But the above diagnosis seems to be correct.

[scztt]

this may be fixed via #1424?

[telephon]

As it seems, #1424 breaks:

{ SinOsc.ar(440, 0, EnvGen.ar(Env([0, 1, 0],[0, 0.5], -3), Impulse.ar(1))) }.play

But I left it in, commented out, so we can continue from that.