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</o:shapelayout></xml><![endif]--></head><body lang=ZH-CN link=blue vlink=purple style='text-justify-trim:punctuation'><div class=WordSection1><p class=MsoNormal><span lang=EN-US>Why a sink input and its sink need “rewind” on corking and uncorking?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>I don’t quite understand the following code. Could somebody kindly shed light on it? And take ALSA sink for example, are there any valid (non-silent) data left in ALSA buffer after the rewinding?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>void pa_sink_input_set_state_within_thread(pa_sink_input *i, pa_sink_input_state_t state) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> …<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> corking = state == PA_SINK_INPUT_CORKED && i->thread_info.state == PA_SINK_INPUT_RUNNING;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> uncorking = i->thread_info.state == PA_SINK_INPUT_CORKED && state == PA_SINK_INPUT_RUNNING;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> if (i->state_change)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> i->state_change(i, state);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> i->thread_info.state = state;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> if (corking) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> pa_log_debug("Requesting rewind due to corking");<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> /* This will tell the implementing sink input driver to rewind<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> * so that the unplayed already mixed data is not lost */<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> pa_sink_input_request_rewind(i, 0, TRUE, TRUE, FALSE); … <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> } else if (uncorking) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> i->thread_info.underrun_for = (uint64_t) -1;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> i->thread_info.playing_for = 0;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> pa_log_debug("Requesting rewind due to uncorking");<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> /* OK, we're being uncorked. Make sure we're not rewound when<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> * the hw buffer is remixed and request a remix. */<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> pa_sink_input_request_rewind(i, 0, FALSE, TRUE, TRUE);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>}<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Thanks<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>Amanda<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>