gstreamer with playbin: how to pause 'now' or pause at exact time

[Tim-Philipp Müller]

On Thu, 2013-09-26 at 22:48 +0200, Alexandru Munteanu wrote:

Hi,

> I am using gstreamer 1.0.10 (packages from debian testing) with the playbin element
> (for mp3splt-gtk).
> 
> When I set the element to GST_STATE_PAUSED, I always have a lag between the moment I call
> gst_element_set_state() and the time when the pause occurs.
> Is there a way to "pause right now" or "pause at a precise time in the future" ?

Sorry for not answering your question, but let me ask you first: what
are you trying to achieve with that? What's the big picture?

 Cheers
  -Tim

> Details follow.
> 
> I have those two functions:
> 
>     void gstreamer_get_time_elapsed(ui_state *ui)
>     {
>       GstQuery *query = gst_query_new_position(GST_FORMAT_TIME);
>       gint64 time = 0;
>   
>       if (gst_element_query(ui->pi->play, query))
>       {
>         gst_query_parse_position(query, NULL, &time);
>       }
>   
>       gst_query_unref(query);
>     
>       fprintf(stdout, "position = %ld\n", time);
>       fprintf(stdout, "position / MSECOND = %ld\n", time / GST_MSECOND);
>       fflush(stdout);
>     }
> 
>     void gstreamer_pause(ui_state *ui)
>     {
>       GstState state;
>       gst_element_get_state(ui->pi->play, &state, NULL, GST_CLOCK_TIME_NONE);
> 
>       fprintf(stdout, "time before pause\n");
>       gstreamer_get_time_elapsed(ui);
> 
>       fprintf(stdout, "setting pause ...\n");
>       fflush(stdout);
>       GstStateChangeReturn ret = gst_element_set_state(ui->pi->play, GST_STATE_PAUSED);
>       if (ret == GST_STATE_CHANGE_ASYNC)
>       {
>         fprintf(stdout, "async!\n");
>         fflush(stdout);
>       }
>       else if (ret == GST_STATE_CHANGE_SUCCESS)
>       {
>         fprintf(stdout, "success!\n");
>         fflush(stdout);
>       }
> 
>       fprintf(stdout, "time after pause ...\n");
>       fflush(stdout);
>       gstreamer_get_time_elapsed(ui);
>     }
> 
> and when I call gstreamer_pause(), I get the following output:
> 
>     time before pause
>     position = 90017369614
>     position / MSECOND = 90017
>     setting pause ...
>     success!
>     time after pause ...
>     position = 90343673468
>     position / MSECOND = 90343
> 
> There is a difference of about 0.3 second between the moment just before I pause
> and the moment the pause is triggered.
> Any idea how I can handle this issue ?
> 
> Thank you.
>