FlowCombiner

Added in version 1.4.

class FlowCombiner(**kwargs)

Utility struct to help handling FlowReturn combination. Useful for FlowReturn for those pads.

FlowCombiner works by using the last FlowReturn for all Pad it has in its list and computes the combined return value and provides it to the caller.

To add a new pad to the FlowCombiner use add_pad(). The new Pad is stored with a default value of %GST_FLOW_OK.

In case you want a Pad to be removed, use remove_pad().

Please be aware that this struct isn’t thread safe as its designed to be

used by demuxers, those usually will have a single thread operating it.

These functions will take refs on the passed :obj:`~gi.repository.Gst.Pad`<!– –>s.

Aside from reducing the user’s code size, the main advantage of using this helper struct is to follow the standard rules for FlowReturn combination. These rules are:

  • %GST_FLOW_EOS: only if all returns are EOS too

  • %GST_FLOW_NOT_LINKED: only if all returns are NOT_LINKED too

  • %GST_FLOW_ERROR or below: if at least one returns an error return

  • %GST_FLOW_NOT_NEGOTIATED: if at least one returns a not-negotiated return

  • %GST_FLOW_FLUSHING: if at least one returns flushing

  • %GST_FLOW_OK: otherwise

%GST_FLOW_ERROR or below, GST_FLOW_NOT_NEGOTIATED and GST_FLOW_FLUSHING are returned immediately from the update_flow() function.

Constructors

class FlowCombiner
classmethod new() → FlowCombiner

Creates a new FlowCombiner, use free() to free it.

Added in version 1.4.

Methods

class FlowCombiner
add_pad(pad: Pad) → None

Adds a new Pad to the FlowCombiner.

Added in version 1.4.

Parameters:

pad – the Pad that is being added

clear() → None

Removes all pads from a FlowCombiner and resets it to its initial state.

Added in version 1.6.

free() → None

Frees a FlowCombiner struct and all its internal data.

Added in version 1.4.

remove_pad(pad: Pad) → None

Removes a Pad from the FlowCombiner.

Added in version 1.4.

Parameters:

pad – the Pad to remove

reset() → None

Reset flow combiner and all pads to their initial state without removing pads.

Added in version 1.6.

update_flow(fret: FlowReturn) → FlowReturn

Computes the combined flow return for the pads in it.

The FlowReturn parameter should be the last flow return update for a pad in this FlowCombiner. It will use this value to be able to shortcut some combinations and avoid looking over all pads again. e.g. The last combined return is the same as the latest obtained FlowReturn.

Added in version 1.4.

Parameters:

fret – the latest FlowReturn received for a pad in this FlowCombiner

update_pad_flow(pad: Pad, fret: FlowReturn) → FlowReturn

Sets the provided pad’s last flow return to provided value and computes the combined flow return for the pads in it.

The FlowReturn parameter should be the last flow return update for a pad in this FlowCombiner. It will use this value to be able to shortcut some combinations and avoid looking over all pads again. e.g. The last combined return is the same as the latest obtained FlowReturn.

Added in version 1.6.

Parameters: