GstCollectPads

Manages a set of pads that operate in collect mode. This means that control is given to the manager of this object when all pads have data.

• Collectpads are created with gstbase.collect_pads.CollectPads.new_. A callback should then be installed with gst_collect_pads_set_function ().
• Pads are added to the collection with gstbase.collect_pads.CollectPads.addPad/ gstbase.collect_pads.CollectPads.removePad. The pad has to be a sinkpad. When added, the chain, event and query functions of the pad are overridden. The element_private of the pad is used to store private information for the collectpads.
• For each pad, data is queued in the _chain function or by performing a pull_range.
• When data is queued on all pads in waiting mode, the callback function is called.
• Data can be dequeued from the pad with the gstbase.collect_pads.CollectPads.pop method. One can peek at the data with the gstbase.collect_pads.CollectPads.peek function. These functions will return null if the pad received an EOS event. When all pads return null from a gstbase.collect_pads.CollectPads.peek, the element can emit an EOS event itself.
• Data can also be dequeued in byte units using the gstbase.collect_pads.CollectPads.available, gstbase.collect_pads.CollectPads.readBuffer and gstbase.collect_pads.CollectPads.flush calls.
• Elements should call gstbase.collect_pads.CollectPads.start and gstbase.collect_pads.CollectPads.stop in their state change functions to start and stop the processing of the collectpads. The gstbase.collect_pads.CollectPads.stop call should be called before calling the parent element state change function in the PAUSED_TO_READY state change to ensure no pad is blocked and the element can finish streaming.
• gstbase.collect_pads.CollectPads.setWaiting sets a pad to waiting or non-waiting mode. CollectPads element is not waiting for data to be collected on non-waiting pads. Thus these pads may but need not have data when the callback is called. All pads are in waiting mode by default.