[pulseaudio-discuss] Best Case Latency

[Tanu Kaskinen]

On Wed, 2013-09-18 at 04:28 +1000, Patrick Shirkey wrote:
> Hi,
> 
> Can someone shed some light on the best case and typical latency that
> Pulse provides for standard operations?

What do you mean by standard operations? I'd estimate volume changes
etc. normally (on an ALSA sink) have a few millisecond latency (best
case 0.5 ms audio buffer + scheduling latency).

> Also how that is affected by using jack-sink assuming jack is set to the
> lowest possible latency that a device can handle?

When jackd asks for N frames from PulseAudio, pulseaudio will render N
frames. There's no extra buffering done in the Jack sink, so volume
changes etc. will have latency that is roughly the same as the normal
Jack client latency.

If by "standard operations" you meant the stream latency that PulseAudio
clients see (in which case "standard operations" is a strange way to say
it, IMO), then that depends on what the clients request. If they let
PulseAudio choose, the latency is typically 2 seconds. If they want
minimal latency, with infinite CPU power I think the lower bound is
maybe a couple of milliseconds, but since computers don't have infinite
CPU power, the practical limit is some tens of milliseconds based on
what I've heard (the exact limit naturally depends on how beefy the CPU
is).

-- 
Tanu