Playing sound on the client
Note:This article is still work in progress…
It may be interesting in some cases to be able to play (and record) sound on the client. You guess, however, that it is not as easy as that.
As we use GNOME as our preferred Desktop Environment, we will try to describe how to do it using EsounD, the default sound daemon for GNOME, or Polypaudio, its successor.
First, you need to have a sound card in the client.
Then, you need it to be supported by the kernel, using OSS or, better, ALSA.
Next, you need to start EsounD (program name: esd) or Polypaudio at startup on the client, with the -public option activated, allowing TCP connections with the -tcp option and configuring the /etc/hosts.allow and /etc/hosts.deny to allow it also.
And finally, you need to instruct your applications to use the sound server on that machine (this is the tricky part). The ESPEAKER environment variable is there for this purpose, exactly like DISPLAY. I guess you only need to extract a part of DISPLAY and use it to build ESPEAKER. EsounD also features a kind of OSS emulator for applications.