[pulseaudio-discuss] [RFC] Dynamic reconfiguration of sampling rate

Colin Guthrie gmane at colin.guthr.ie
Wed Jan 19 16:33:26 PST 2011

'Twas brillig, and pl bossart at 19/01/11 21:48 did gyre and gimble:
>>> I think the general idea was to stop the pops and clicks that would be
>>> apparent on some devices (maybe some HDA?) when the device is opened and
>>> closed (and also to be slightly more responsive but that's probably a
>>> trivial advantage on any machine made this millennium!).
>>> So I'm not sure we can idle at 0s as a general rule, but as I have very
>>> limited test hardware (namely my laptop and couple other machine which
>>> aren't really meant for testing!), I can't really say this with any
>>> degree of confidence.
>> I'll do more testing later today. I could see some issues with
>> networking or interfaces like S/PDIF or HDMI, where the receiver needs
>> to relock. But for local playback we should be fine. You will still
>> send zeroes out as soon as the sink-input is created, and there'll be
>> an interval before the first valid sample is provided by the
>> application.
> I tried with several outputs, USB headset and speakers, no
> clicks/pops. On the SPDIF or HDMI outputs though, my receiver does
> reset the DACs when it loses the sync, and there are definitely some
> short pops.
> In other words we would need to introduce a timeout value for each
> profile, not sure how to go about this. There's really no difference
> from the PulseAudio level between a USB headset that can be
> reconfigured and a receiver connected by SPDIF through an M-Audio USB
> card...

Perhaps a timeout can be pushed into the proplists? The profile logic
maybe be extended to offer different timeouts directly or to make it
more configurable specify a "timeoutgroup = quick|delayed" type value
with idle-quick-timeout and idle-delayed-timeout added to daemon.conf?

There are maybe beter ideas tho' as I'm quite tired. Night night!



Colin Guthrie

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