Free workaround for listening to server audio from client

Rasmus Emil Møller AER "at"
Thu, 30 Aug 2001 17:24:48 +0000

Hello list,

Slightly off topic, but... in the past there has been quite a few questions
about how to push the sound as well as the desktop to the client.

I have found a way to push the sound from a Windows NT/9x box (with the VNC
server) to one or more Windows NT/9x/Linux/Unix clients.

On the WinVNC server machine I first install Virtual Audio Cable from

- the free demo version is sufficient. It installs a virtual sound card
with automatic loopback - i.e. all sound played to the virtual sound card
output channel is immediately available on the input channel. A physical
sound card is not necessary - if you have a physical sound card, you may
have to check the Multimedia settings from the Control Panel to see which
card is default for input/output.

So now we just need a program to capture the sound input and send it to the
clients. I tried Speak Freely, which is free, open source and available for
Windows (, Unix ( and Linux ( Win source code link:

Speak Freely needs no installation, just copy the files. There are many
settings and possibilities.

It uses UDP, and you can specify the port.

It uses its native protocol or RTP or VAT.

It offers many different compression schemes - the most efficient in terms
of bandwidth requires 800 bytes/second. Watch out for CPU usage.

It offers multicast - I didn't try it, probably works fine.

It offers broadcast - which in Speak Freely terms means unicast the same
audio to each connected client.

It offers voice activation to send automatically when there is sound - I
used "Fast".

It offers a number of encryption schemes - watch out for CPU usage.

Feel free to address me, if you have questions.

Cordiali saluti

Rasmus E. Mxller

IT Systemprogrammering PC


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