[pulseaudio-discuss] volume ramping

Baek Chang baeksan at ccrma.stanford.edu
Mon Dec 15 17:12:24 PST 2008


I were to utilize a ramping function to process a block of audio in a
sink-input, where should this be called?  I tried using inserting a ramping
routine on a sink-input within pa_sink_input_peek(), in sink-input.c

This seems to give me strange results.  Any suggestions on where I could
process the audio data of individual sink-inputs before it gets mixed down
into a single sink?

Thanks in advance
Baek

On Thu, Dec 11, 2008 at 10:04 AM, Lennart Poettering <lennart at poettering.net
> wrote:

> On Thu, 11.12.08 09:56, Baek Chang (baeksan at ccrma.stanford.edu) wrote:
>
> > What is the proper way to do volume ramping in pulse audio to avoid
> clicking
> > when changed the volume?  I wrote a module to callback and change the
> volume
> > in small incremental steps, but it seems that pulse seems to apply the
> > volume changes on the audio buffer as a whole.  Does pulseaudio take a
> > volume command, and then process the one audio buffer with that set
> volume?
> > I'm using a buffer size of 4096 at 44100Hz, so it is about 10mS. So how
> > would I go about ramping the volume, in say about 15 mS?
>
> Volumes are applied block-by-block. The Block size is variable and
> depends on the sound device and the application used.
>
> I wrote some code to implement volume "envelopes" for this. The code
> is there, it's even included in the tarball.  But it's not hooked
> up. And until I finish that I fear, no: we cannot do volume ramping.
>
> Sorry,
>
> Lennart
>
> --
> Lennart Poettering                        Red Hat, Inc.
> lennart [at] poettering [dot] net         ICQ# 11060553
> http://0pointer.net/lennart/           GnuPG 0x1A015CC4
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-- 
Baek Chang
baeksan at ccrma.stanford.edu
407-267-6701
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