Re: [freesci-develop] SCI01 cues and loop events

[Lars Skovlund]

On Mon, Feb 02, 2004 at 09:02:16PM +0100, Christoph Reichenbach wrote:

> Hi,
> 
> I'm somewhat confused by SCI01' handling of cues and loops-- to my
> understanding, each of the separate channels loops separately, and may
> also issue cues separately. 

That is not true. How do you reach that conclusion?

> When, precisely, are these events reported to the VM objects?

Loops are not communicated to the VM objects and are binary only
(i.e. you can't specify a number of iterations). 

Cues are the most complicated of the two, since the mechanism has
changed quite a bit. There are now separate counters for what we used
to call absolute and cumulative cues. Absolute cues are generally
stored in the signal selector, and cumulative cues are generally
stored in the dataInc selector, with some interesting twists: 

1. The server's record of the absolute cue value is reset as part of
UPDATE_CUES. 
2. When a cumulative cue is reported to the VM object, it will be
placed in _both_ fields. In such a case, a constant of 0x7f will be
added to the _signal_ selector only, to be able to distinguish the two
kinds of cue (this has already been coded). 
3. The above only happens if the sound does not use absolute cues
(i.e. if the signal is 0 a priori). Note that, because of 1)
above, this does not cause problems neither with successive cumulative
cues nor with mixed cumulative/absolute cues.
4. A signal of 0xff will stop the sound object playing. This may be
for purely internal purposes.

> -- Christoph

Lars