Finding All Channel Objects?

Question

I am working on an audio player that will take a parameter
from a web page and play the appropriate MP3 file. Each page in a
series of pages calles the same movie. It works but I have a
seriouis problem with the code. If the user navigates to the next
page while the current page is still playing the audio, the new
audio is played on top of the older clip. I suspect that each time
the same movie is called, a new SoundChannel object is being
created.
I'd like to come up with a function to search all current
objects that are not in the display list and issue a Stop command
to all existing SoundChannel objects.
Does anyone know if it is possible to write a function to do
this? Have you written such a function? I can't come up with any
other way to stop the currenlty playing audio automatically. I
can't rely on the user to stop it manually...
The SoundMixer.stopAll(); doesn't work, I've tried it. :-(
TIA
Peter H.

Answer 1

Peter,
> Finally, I have a function to play the sound with a
line:
>
> _channel = _snd.play(_pausePosition);
Everything you've described sounds fine. For what it's
worth, you don't
actually have to wait until the sound fully loads before
issuing the
Sound.play() method (the sound will progressively download,
which means it
starts playing as soon as enough data have loaded) -- but
again, your
description so far sounds just fine.
> I suspect that each time the SWF is called to play
another
> MP3, the code is creating another Channel object and
> playing the newly requested MP3.
This is the part that puzzled me at first, but now I think I
understand.
What I missed in my first read-through was that the new page
starts playing
while the initial page is still open. That means there are
two instances of
Flash Player running, each with the same SWF, but a different
parameter.
Even though both instances of Flash Player are playing the
same SWF, each
instance comprises its own unique world. You can't (easily)
enumerate the
objects in both SWFs in a collaborative way, because they're
separate
entities -- twins, if you will, but still unique human
beings.
> Specifically, I was thinking that if I had a way to
identify
> all Channel objects instantiated within this movie, I
could
> just do something to unload them all from memory to
> ensure none were already playing.
By the looks of it, each of your SWF instances, across
x-number of HTML
pages, has a single, named SoundChannel instance: _channel.
So it isn't as
if you really have to search for instances -- you know them
at this point --
it's that you have to get separate SWFs to speak to each
other and figure
out who needs to keep mum.
Off the top of my head, I can imagine using JavaScript to
feed a second
parameter to the SWF that a given page opens. The first
parameter, of
course, is the MP3 to play. The second parameter could be a
timestamp.
This way, each page has an "age," and you could feasibly
communicate from
SWF to SWF with instructions that only the youngest SWF be
allowed to play.
Inter-SWF communication happens with the LocalConnection
class. You set
up an arbitrarily named line of communication, then "listen"
to that line.
SWFs can also send messages over one or more lines. See if
that gets you
started, and be sure to come back if you have additional
questions. I'm
interested in this topic myself now, so I'll try to work up a
proof of
concept on my own and we can swap notes. :)
David Stiller
Adobe Community Expert
Dev blog,
http://www.quip.net/blog/
"Luck is the residue of good design."