[pulseaudio-discuss] Fade-In/Fade-Out Effect

[Arun Raghavan]

On Mon, 2011-10-17 at 17:46 +0900, Yogesh Sharma wrote:
> Hello All
>         
> How to get Fade-in/Fade-out effect using pulseaudio APIs.
> As Arun says in Article
> http://arunraghavan.net/2011/05/more-pulseaudio-power-goodness/
> "PulseAudio doesn’t offer an API to do fades" , is there any way to get
> fade effects in pulseaduio. 

My blog post talks about doing fades on a GStreamer pipeline for the
generic case. You should still be able to implement your own fades
without too large an effort if you're not trying to build a generic
framework out of it.

If you do want to do a generic thing, we really need the proper
API/infrastructure to implement effects and this is somewhat
non-trivial.

> And if pulseaudio does not support fade effect then what are these APIs
> meant for pa_cvolume_get_fade(), pa_cvolume_set_fade() and
> pa_cvolume_get_fade(). 
> I tried to use these APIs but did not get any success.

As you'll find in the documentation, in this context, the fade is the
balance between front and rear channels:

http://freedesktop.org/software/pulseaudio/doxygen/volume_8h.html#aaf78aa9297c11860338ffa3c958f9a36

-- Arun