[pulseaudio-discuss] Overrun in Pulseaudio8.0 when switching endpoints

Nishit Sharma sharmafrequent at gmail.com
Sun Sep 18 12:26:43 UTC 2016

Please find the reply below:-

On Sun, Sep 18, 2016 at 5:19 PM, Tanu Kaskinen <tanuk at iki.fi> wrote:

> On Sat, 2016-09-17 at 17:51 +0530, Nishit Sharma wrote:
> > Hi All,
> >
> > I have observed strange behavior of PulseAudio8.0 which is as:-
> > I have one card which have 2 devices AMIC and DMIC. I am using ALSA, UCM
> > config files with PulseAudio. Before pulseaudio boots up Headset and DMIC
> > have been connected on card.
> What does "connected on card" mean?
   *On a sound card we have AMIC, DMIC, Speaker as different Playback and
Capture devices *

> > When PulseAudio boots up it initializes AMIC (
> > Headset ) only and i can record using it.
> > Now, the problem starts. When i plugged Headset the Port switching done
> > from AMIC to DMIC and after sometime i got overrun without recording
> > anything.
> You seem to be saying that AMIC is the same thing as Headset

   *Yes AMIC is detected as HeadSet when executed pulseaudio*

 but then you say that when the headset is plugged in, the port changes
> from AMIC
> to DMIC, which doesn't make sense.

   * I missed one thing, when i plugged out Headset from target board,
pulseaudio switches port from AMIC to DMIC*
*    which i think should initializes ( hw params ) DMIC first as done for

Why would the port change away from
> the headset when the headset is plugged in? Did you mix up AMIC and
> DMIC at some point in your description?
> *Explained above ( When Headset plugged out the switching happened from
> AMIC port to DMIC port )*

> > My analysis:- PulseAudio should initialize both AMIC and DMIC ( setting
> hw
> > params and other stuff ) but only AMIC initialized. Only port switching
> > should not have been happened as no hw params setup for DMIC. Port
> switched
> > but PulseAudio is expecting I/P for AMIC. Am i right here?
> Hw params are set when opening the PCM device. If AMIC and DMIC are on
> the same PCM device, there's no need to reconfigure the hw params (or
> if the hardware requires such reconfiguration, pulseaudio certainly
> won't do it). It's a bit unclear unclear whether AMIC and DMIC are on
> same or different PCM devices, but if they are two ports on the same
> sink, then they are on the same PCM device.
> *   If it is so then DMIC will be accepting HW params which were set for
AMIC ( HeadSet ), but then there will be difference between the period
size, buffer size passed to DMIC sink which **again can cause problem? *

> I have no idea what you mean by "I/P".
> --
> Tanu
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