[pulseaudio-discuss] Any way to get PA to wake up less when playing low latency?

[Dylan Reid]

On Tue, Oct 25, 2011 at 9:31 AM, Pierre-Louis Bossart
<pierre-louis.bossart at linux.intel.com> wrote:
>
> Hi Dylan,
> please use plain text in your messages, HTML makes it hard to quote your
> text...
>
> Your idea of having fewer wakes makes sense. Just technically I think you
> are confusing latency with frame size. if you want to use 10ms frames for
> speech processing, you will have a 20ms latency, be that with ALSA or
> PulseAudio.
Understood, I wasn't worrying about frame sizing yet.  Just passing through
unprocessed samples to start.  If I was to have 10ms frames (likely) I'd want
to have an audio wake from the output every 10ms.

> Also I think you've hit an issue with PulseAudio's inner details. The idea
> is that there's a server side buffer that has the same length than the ALSA
> ring buffer. This makes sense for low-power audio, so that you can wake-up
> at the last moment and quickly fill the ring buffer. For low-latency, this
> might not be such a good idea, since it entails many useless wakes and the
> client does have the data available. This behavior is enforced in
> pulsecore/protocol-native.c, it may be possible to patch this code to reduce
> the server side buffer to zero (or minreq).
Thanks for the pointer, I'll take a look in that area and see if it's
something easy.

> This might be a good point to bring to Lennart, if he still remembers what
> he wrote a couple of years ago. Lennart are you still with us?
> -Pierre
>
>
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