[pulseaudio-discuss] Support for audio envelopes

[Flavio Ceolin]

"Jaska Uimonen" <jaska.uimonen at helsinki.fi> writes:

Hi Jaska,

> Hello,
>
> For some reason the company mail server is holding back the
> patches, doing some checking or what not... I sent the
> patches to the mailing list last Thursday. This happened
> to me once before, but I didn't remember to take it into
> account...
>
> Anyway if they are not appearing soon to the list, I will
> resend them from home.
>
> br,
> Jaska
>

Thanks for update me, i'm waiting your patch so.

Regards,
Flavio Ceolin
>
> Quoting "Flavio Ceolin" <flavio.ceolin at profusion.mobi>:
>
>> Hi folks,
>>
>>> 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
>>
>> Trying to continue this matter, the idea of make this funcionality so
>> generic is facilitating for other applications. I believe several
>> applications (like media players) that use PA are implementing it's own
>> "basic" effects as crossfading or fade-in/out for pause. I think make it
>> easier is a goal.
>>
>> Other benefit of supporting it, is make possible the ducking[1] effect on
>> audio streams, as we've discussed on irc, a good example for this is the
>> sms case (when a sms comes the others samples should fade-out).
>>
>> Another point to have it is the sample cache. If the sample is already
>> in the cache and the application should do fade-in/out or change the
>> balance, the only way to do that is re-uploading the sample.
>>
>> So guys, what you think about, it worth to implement ? If not, what you
>> think should be changed ? I'm open to discuss it.
>>
>>
>> [1] http://en.wikipedia.org/wiki/Ducking
>>
>>
>> Regards,
>> Flavio Ceolin
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