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Top-level bin with clocking and bus management functionality.
A <gst-pipeline> is a special <gst-bin> used as the toplevel
container for the filter graph. The <gst-pipeline> will manage the
selection and distribution of a global <gst-clock> as well as provide a
<gst-bus> 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
<gst-element> objects (if not otherwise referenced).
Elements are added and removed from the pipeline using the <gst-bin>
methods like gst-bin-add and gst-bin-remove (see
<gst-bin>).
Before changing the state of the <gst-pipeline> (see
<gst-element>) a <gst-bus> can be retrieved with
gst-pipeline-get-bus. This bus can then be used to receive
<gst-message> from the elements in the pipeline.
By default, a <gst-pipeline> will automatically flush the pending
<gst-bus> messages when going to the NULL state to ensure that no
circular references exist when no messages are read from the <gst-bus>.
This behaviour can be changed with gst-pipeline-set-auto-flush-bus.
When the <gst-pipeline> 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 <gst-system-clock> 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 <gst-pipeline> 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)
This
<gobject>class defines the following properties:
delay- Expected delay needed for elements to spin up to PLAYING in nanoseconds
auto-flush-bus- Whether to automatically flush the pipeline's bus when going from READY into NULL state
mchars) (ret <gst-element>)Create a new pipeline with the given name.
- name
- name of new pipeline
- ret
- newly created GstPipeline MT safe.
<gst-pipeline>) (ret <gst-bus>)Gets the
<gst-bus>of pipeline.
- pipeline
- a
<gst-pipeline>- ret
- a
<gst-bus>, unref after usage. MT safe.
<gst-pipeline>) (clock <gst-clock>) (ret bool)Set the clock for pipeline. The clock will be distributed to all the elements managed by the pipeline.
- pipeline
- a
<gst-pipeline>- clock
- the clock to set
- ret
- TRUE if the clock could be set on the pipeline. FALSE if some element did not accept the clock. MT safe.
<gst-pipeline>) (ret <gst-clock>)Gets the current clock used by pipeline.
- pipeline
- a
<gst-pipeline>- ret
- a
<gst-clock>, unref after usage.
<gst-pipeline>) (clock <gst-clock>)Force pipeline to use the given clock. The pipeline will always use the given clock even if new clock providers are added to this pipeline.
If clock is NULL all clocking will be disabled which will make the pipeline run as fast as possible.
MT safe.
- pipeline
- a
<gst-pipeline>- clock
- the clock to use
<gst-pipeline>)Let pipeline select a clock automatically. This is the default behaviour.
Use this function if you previous forced a fixed clock with
gst-pipeline-use-clockand want to restore the default pipeline clock selection algorithm.MT safe.
- pipeline
- a
<gst-pipeline>
<gst-pipeline>) (time unsigned-long-long)Set the new stream time of pipeline to time. The stream time is used to set the base time on the elements (see
gst-element-set-base-time) in the PAUSED->PLAYING state transition.Setting time to
<gst-clock-time-none>will disable the pipeline's management of element base time. The application will then be responsible for performing base time distribution. This is sometimes useful if you want to synchronize capture from multiple pipelines, and you can also ensure that the pipelines have the same clock.MT safe.
- pipeline
- a
<gst-pipeline>- time
- the new stream time to set
<gst-pipeline>) (ret unsigned-long-long)Gets the last stream time of pipeline. If the pipeline is PLAYING, the returned time is the stream time used to configure the element's base time in the PAUSED->PLAYING state. If the pipeline is PAUSED, the returned time is the stream time when the pipeline was paused.
This function returns
<gst-clock-time-none>if the pipeline was configured to not handle the management of the element's base time (seegst-pipeline-set-new-stream-time).
- pipeline
- a
<gst-pipeline>- ret
- a
<gst-clock-time>. MT safe.
<gst-pipeline>) (auto_flush bool)Usually, when a pipeline goes from READY to NULL state, it automatically flushes all pending messages on the bus, which is done for refcounting purposes, to break circular references.
This means that applications that update state using (async) bus messages (e.g. do certain things when a pipeline goes from PAUSED to READY) might not get to see messages when the pipeline is shut down, because they might be flushed before they can be dispatched in the main thread. This behaviour can be disabled using this function.
It is important that all messages on the bus are handled when the automatic flushing is disabled else memory leaks will be introduced.
MT safe.
- pipeline
- a
<gst-pipeline>- auto-flush
- whether or not to automatically flush the bus when the pipeline goes from READY to NULL state
Since 0.10.4
<gst-pipeline>) (ret bool)Check if pipeline will automatically flush messages when going to the NULL state.
- pipeline
- a
<gst-pipeline>- ret
- whether the pipeline will automatically flush its bus when going from READY to NULL state or not. MT safe.
Since 0.10.4
<gst-pipeline>) (delay unsigned-long-long)Set the expected delay needed for all elements to perform the PAUSED to PLAYING state change. delay will be added to the base time of the elements so that they wait an additional delay amount of time before starting to process buffers and cannot be
<gst-clock-time-none>.This option is used for tuning purposes and should normally not be used.
MT safe.
- pipeline
- a
<gst-pipeline>- delay
- the delay
Since 0.10.5