Channel setVolume. How it works?

unlying · January 2013

Hello.
Plz, explain me how it works. I spend more then hour and still can't find what i'm doing wrong
Here is code:

 music = Sound.new("mus/heal.wav")
		channel:setVolume(0.0)
		print(channel:getVolume())
		channel  = music:play(0, 1)
		print(channel:getVolume())

and sound plays. I have 0 and 1 in output.
How to set Volume to 0 forever?

hnim · January 2013

@unlying: if you want to set volume to 0 (or other value) forever, why you dont change your own gfx files?
when you call music:play(), it returns new channel, so volume will back to 1. If you want to play sound/music with custom volume, you can write some util funtions

function play(snd, vol)
     local channel = snd:play()
     channe:setVolume(vol)
     --return channel
end

unlying · January 2013

It is weird. To set Volume everytime when i play sound. I used it in my first projects by Gideros. But it is really-really weird. After that i just don't care about sound volume.
It should be normal way to set volume for channel.

plamen · January 2013

channel = music:play(0, 1) - this is the moment when channel is created.
you can set the volume or get the volume after it.

unlying · January 2013

I don't think that it is ok. If we really should set volume everytime when we play any sound, then it should be changed.

atilim · January 2013

@unlying When a new object is created (like SoundChannel), all of its properties are set to default values. And the default value of the volume of a SoundChannel object is 1.

For example alpha is a property of Sprite and its default value is 1:

sprite = Sprite.new()
sprite:setAlpha(0)
print(sprite:getAlpha())	--> prints 0
sprite = Sprite.new()
print(sprite:getAlpha())	--> prints 1

And volume behaves exactly the same way.

ar2rsawseen · January 2013

And it could be easily by passed

function Sound:setVolume(volume)
    self._volume = volume
end
 
Sound._play = Sound.play
 
function Sound:play(...)
    local sound = self:_play(...)
    if self._volume then
        sound:setVolume(self._volume)
    end
    return sound
end

Something similar to this is done in GiderosCodingEasy only there you can control the volume of whole app (all sounds and musics of an app

)

unlying · January 2013

In russian we spell it like "crutches"
It should be transparent way to set default values for these things.

asakharov · January 2013

@atilim, Is it possible to add method setDefaultVolume(value) to Sound class? Or pass it to constructor, or play method.
And why do we need separation of Sound and Sound channel? To download music once and play over and over? (To save memory.)
It would be great to have a resource pool with lazy loading for music and other resources. Then you could get rid of classes like SoundChannel

OZApps · January 2013

I guess what you are asking for is like a Master Volume, so if you set the volume to 0.2 then all sounds/music loaded and played thereafter should play at that volume. In the current scenario the only thing required would be to create a wrapper function that would set up the volume as required.

gmarinov · June 2013

@unlying - there's volume control at the speaker already so simply make your sounds consistent if you don't want to do anything else. For a volume setting in your app, wrap sound:play to apply setVolume immediately. It's a great rabbit hole..

I actually like SoundChannel, especially with the events.

There's also the concept of sound layers (background, fx e.g. weapons, bonuses/pick-ups, music, UI). So maybe we can have the SoundChannel subscribe to event notifications for the "layer" it's on, to keep track of the global layer gain/volume, then it's a matter of wrapping setVolume() to apply that correction. I'm working on something similar, so I'll test this theory..

gmarinov · June 2013

Here's what I ended up with.

Event.snd_layer_volume_change = "snd_slvc"	-- any string
 
SoundLayer = Core.class(EventDispatcher)
SoundLayer.name = "default"
SoundLayer.vol  = 1
 
function SoundLayer:setVolume(v)
	self.vol = v	
	self:dispatchEvent(Event.new(Event.snd_layer_volume_change))
end
function SoundLayer:getVolume()
	return self.vol
end
 
 
 
SoundChannel.layer_ref 	= nil			-- holds SoundLayer reference
SoundChannel.vol	= 1			-- full whack
function SoundChannel:set_layer(l)		-- l is a SoundLayer or NIL to detach
	if not l then
		if self.layer_ref then 
			self.layer_ref:removeEventListener(
				Event.snd_layer_volume_change, 
				self.on_layer_volume_change, 
				self ) 
		end
	end
	self.layer_ref = l
	if (self.layer_ref) then
		l:addEventListener(
			Event.snd_layer_volume_change, self.on_layer_volume_change, self)
	end
end
 
function SoundChannel:on_layer_volume_change()
	self:set_volume_with_globalgain(self.vol)
end
 
function SoundChannel:set_volume_with_globalgain(vol) 
	-- sanity checks
	if not vol then return end
	self.vol = vol
	local global_vol = 1
	if (self.layer_ref and self.layer_ref.vol) 
		then global_vol = self.layer_ref:getVolume() 
	end
 
	vol = vol * global_vol
	if (vol < 0) then vol = 0 end
	if (vol > 1) then vol = 1 end
 
	self:setVolume(vol);
end

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