Event "state change" handling from element to element?

[philippe renon]

Hi,
There is a lot of information here : https://gstreamer.freedesktop.org/documentation/design/index.html
Most of them are a must read if you are new to GStreamer.

There's a page about Event handling.
Cheers,
Philippe.

 

    Le Vendredi 19 octobre 2018 17h51, "Maurer, Marie" <marie.maurer at zeiss.com> a écrit :
 

  <!--#yiv4509015314 _filtered #yiv4509015314 {font-family:"Cambria Math";panose-1:2 4 5 3 5 4 6 3 2 4;} _filtered #yiv4509015314 {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;}#yiv4509015314 #yiv4509015314 p.yiv4509015314MsoNormal, #yiv4509015314 li.yiv4509015314MsoNormal, #yiv4509015314 div.yiv4509015314MsoNormal {margin:0cm;margin-bottom:.0001pt;font-size:11.0pt;font-family:"Calibri", sans-serif;}#yiv4509015314 a:link, #yiv4509015314 span.yiv4509015314MsoHyperlink {color:#0563C1;text-decoration:underline;}#yiv4509015314 a:visited, #yiv4509015314 span.yiv4509015314MsoHyperlinkFollowed {color:#954F72;text-decoration:underline;}#yiv4509015314 span.yiv4509015314E-MailFormatvorlage17 {font-family:"Arial", sans-serif;color:windowtext;}#yiv4509015314 .yiv4509015314MsoChpDefault {font-family:"Calibri", sans-serif;} _filtered #yiv4509015314 {margin:70.85pt 70.85pt 2.0cm 70.85pt;}#yiv4509015314 div.yiv4509015314WordSection1 {}-->Hello,    can someone give or point me to some info, how event handling is working internally between two element?    E.g. end of pipeline contains of a queue and an appsink.    … -> queue -> appsink    Appsink does not want to go to PLAYING state, other elements in this pipeline do it without problems. In result the pipeline itself does not go into PLAYING state.    How are states exchanged between elements? How are the neighbor elements connected? Is it all going via some common code inside gstreamer? So queue is sending state to Gstreamer code and Gstreamer code gives state event to appsink?    Or is the queue element directly connected to the appsink element? So queue is sending state directly to appsink element?    Is there some debugging possibility to see why state event is not running through till the end? I have a bushandler which logs state changes for each element and I see my queue is going to PLAYING, but appsink remains in READY, even when pending state is PLAYING.    cameraBusFunc  State changed: MyAppSink, oldState=NULL, newState=READY, pendingState=PLAYING    cameraBusFunc  State changed: MyQueue, oldState=NULL, newState=READY, pendingState=PLAYING cameraBusFunc  State changed: MyQueue, oldState=READY, newState=PAUSED, pendingState=PLAYING cameraBusFunc  State changed: MyQueue, oldState=PAUSED, newState=PLAYING, pendingState=VOID_PENDING    After this nothing more happens…    Any idea or hint?    Many thanks!    Best regards,    Marie    _______________________________________________
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