[pulseaudio-discuss] data exchange using shared memory

Justin Tulloss jmtulloss at gmail.com
Thu Oct 18 12:14:14 PDT 2007

There shouldn't be a reason for using a memcopy until you're actually moving
data in/out of the hardware. The audio will travel from through the daemon
without being copied. I would recommend using DMA to finally move the audio
to the hardware, but that's a driver level detail.

If you're having trouble moving the data to and from the daemon itself, the
pulseaudio primitives provide ways of using zero-copy buffers to communicate
with the daemon. The API is documented here:

More details on what you're having trouble with would prompt more useful


On 10/17/07, Deb Briggs <Deb.Briggs at palm.com> wrote:
>  http://www.kernel.org/doc/ols/2007/ols2007v2-pages-145-150.pdf says that
> local clients can exchange audio data with a local PulseAudio daemon through
> shared memory IPC – is there any example code that shows this? Asking
> because we're seeing quite high CPU usage (30%+) when using memcpy in the
> read callback that we install via pa_stream_set_read_callback.
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