Description A GstPipeline is a special GstBin used as the toplevel container for the filter graph. The GstPipeline will manage the selection and distribution of a global GstClock as well as provide a GstBus to the application. It will also implement a default behavour for managing seek events (see gst_element_seek()). gst_pipeline_new() is used to create a pipeline. when you are done with the pipeline, use gst_object_unref() to free its resources including all added GstElement objects (if not otherwise referenced). Elements are added and removed from the pipeline using the GstBin methods like gst_bin_add() and gst_bin_remove() (see GstBin). Before changing the state of the GstPipeline (see GstElement) a GstBus can be retrieved with gst_pipeline_get_bus(). This bus can then be used to receive GstMessage from the elements in the pipeline. By default, a GstPipeline will automatically flush the pending GstBus messages when going to the NULL state to ensure that no circular references exist when no messages are read from the GstBus. This behaviour can be changed with gst_pipeline_set_auto_flush_bus(). When the GstPipeline performs the PAUSED to PLAYING state change it will select a clock for the elements. The clock selection algorithm will by default select a clock provided by an element that is most upstream (closest to the source). For live pipelines (ones that return GST_STATE_CHANGE_NO_PREROLL from the gst_element_set_state() call) this will select the clock provided by the live source. For normal pipelines this will select a clock provided by the sinks (most likely the audio sink). If no element provides a clock, a default GstSystemClock is used. The clock selection can be controlled with the gst_pipeline_use_clock() method, which will enforce a given clock on the pipeline. With gst_pipeline_auto_clock() the default clock selection algorithm can be restored. A GstPipeline maintains a stream time for the elements. The stream time is defined as the difference between the current clock time and the base time. When the pipeline goes to READY or a flushing seek is performed on it, the stream time is reset to 0. When the pipeline is set from PLAYING to PAUSED, the current clock time is sampled and used to configure the base time for the elements when the pipeline is set to PLAYING again. This default behaviour can be changed with the gst_pipeline_set_new_stream_time() method. When sending a flushing seek event to a GstPipeline (see gst_element_seek()), it will make sure that the pipeline is properly PAUSED and resumed as well as set the new stream time to 0 when the seek succeeded. Last reviewed on 2006-03-12 (0.10.5)