[pulseaudio-discuss] Accessing audio as root

[Lennart Poettering]

On Sun, 03.01.10 16:34, Colin Guthrie (gmane at colin.guthr.ie) wrote:

> 
> 'Twas brillig, and Bill Cox at 03/01/10 16:23 did gyre and gimble:
> > Speechd-up isn't the only "root" level sound source that's out there.
> > Espeakup is another alternative to speechd-up which is currently much
> > more popular, but limited in that it can only use the espeak voice.
> > From the point of view of developers for such packages, they just want
> > to write to a sound output interface.  Espeakup uses portaudio, and
> > frankly, I don't want to rewrite that interface (one is enough for
> > me).  These processes, even speechd-up, set custom buffering
> > parameters in PA (speechd-up requires the tlength paramter to be much
> > shorter than default). 
> 
> Well in the situation I'm proposing, the speechd-up would actually just
> write it's audio to a pipe (totally bypassing pulse client API), and it
> would be up to module-pipe-source and module-loopback to act as the
> pulse client, reading from the pipe and actually doing the output. The
> buffering metrics can be somewhat adjusted when loading
> module-loopback.

This wont fly. m-p-s assumes the audio you pass to it is clocked. and
m-l depends on that. However the tts audio will not be clocked
properly, and hence things will make boom..

That said, writing a simple module reads audio data from a pipe and
passes directly to a sink should be trivial to do.

Note however that on Unix pipes cannot be used to distribute data to
multiple processes.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4