[pulseaudio-discuss] Support for audio envelopes

[Flavio Ceolin]

Tanu Kaskinen <tanuk at iki.fi> writes:

Hi Tanu,

> On Fri, 2012-07-20 at 17:32 -0300, Flavio Ceolin wrote:
>> Tanu Kaskinen <tanuk at iki.fi> writes:
>> > There were problems with the code. I don't remember what exactly was
>> > broken, though. But at least I didn't like the concurrency handling: I
>> > really dislike doing inter-thread communication by using shared
>> > variables. Instead, message passing should be used, in my opinion.
>> 
>> I'll investigate how to solve it. Btw, do you think it's better start
>> from the scratch or it's ok start from this code ?
>
> I really don't know. I'm not familiar enough with the code to know how
> much of it needs rewriting.
>
> I know that Jaska Uimonen has been working with volume envelopes too,
> and asked him yesterday about the status. He said he will post the code
> to the mailing list on Monday. I haven't seen the code, but if it's
> good, then it might be a good starting point too (Jaska said that it's
> lacking multichannel support, so work will be needed).
>

It's really good to heard it.

>> >> 2) How an application should use this code, AFAIK this code is not being
>> >>    exported.
>> >
>> > What's your use case? If we are talking about sink volume ramping, I
>> > don't see the need for a client interface at all, because it should be
>> > done automatically by the server.
>> 
>> Basically I want to set an envelope which apply a filter changing the
>> sound balance and/or the volume, it's easier demonstrating an idea of an
>> envelope:
>
> But what's the use case (user-visible feature) that you're interested
> in? My answer to the "how an application should use this code" depends
> on the use case.

I want make possible an application associate an action with an audio
effect. For example, a dialog pops up and you want to keep that sample
pattern playing but you want to "fade it out" so its really quiet. So over
2 seconds you fade it out. Another example would be you shift balance to
the left or right according with the mobile phone (or whatever you want)
position.

Regards,
Flavio Ceolin