[pulseaudio-discuss] understanding PA cork/uncorking scenarios

[Himanshu Chug]

Hi

I am trying to understand how the corking/uncorking events reach from PA
module to PA applications/clients e.g gst-launch

Say, we are corking the playback stream in module-cork-music-on-phone by
calling :

apply_cork(struct userdata *u, pa_sink *s, pa_sink_input *ignore, pa_bool_t
cork)
     pa_sink_input_send_event(ignore, PA_STREAM_EVENT_REQUEST_CORK, NULL);
(in sink-input.c)

(pa_hook_fire(&i->core->hooks[PA_CORE_HOOK_SINK_INPUT_SEND_EVENT],
&hook_data)   (function then fire an hook)
                      sink_input_send_event_hook_cb( pa_core *c,
pa_sink_input_send_event_hook_data *data, struct userdata *u)    ( in
module-x11-cork-request, passing *data that contains cork event)


now inside sink_input_send_event_hook_cb( )   ( in module-x11-cork-request )
there is an if-else check

    if (pa_streq(data->event, PA_STREAM_EVENT_REQUEST_CORK))
        sym = XF86XK_AudioPause;
    else if (pa_streq(data->event, PA_STREAM_EVENT_REQUEST_UNCORK))
        sym = XF86XK_AudioPlay;
    else
        return PA_HOOK_OK;

further the same function is calling
    XTestFakeKeyEvent(display, code, True, CurrentTime);
    XSync(display, False);

But it is not clear to me how the Cork/Uncork events then reach to PA client
(say pulsesink or Gst-launch) and then where gst listens to these events and
pause / resume gst pipeline accordingly ?
Is pulsesink involved here somehow ? I can see
gst_pulsering_stream_event_cb( )  function (inside pulsesink.c)  handling
PA_STREAM_EVENT_REQUEST_CORK but currently it is under #ifdef
HAVE_PULSE_0_9_15 flag and disabled.

Thanks in advance,

Best Regards,
Himanshu
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