:right-sidebar: True BaseTransform =================================================================== .. currentmodule:: gi.repository.GstBase .. class:: BaseTransform(**properties: ~typing.Any) :no-contents-entry: Superclasses: :class:`~gi.repository.Gst.Element`, :class:`~gi.repository.Gst.Object`, :class:`~gi.repository.GObject.InitiallyUnowned`, :class:`~gi.repository.GObject.Object` :Constructors: :: BaseTransform(**properties) Methods ------- .. rst-class:: interim-class .. class:: BaseTransform :no-index: .. method:: get_allocator() -> tuple[~gi.repository.Gst.Allocator, ~gi.repository.Gst.AllocationParams] Lets :obj:`~gi.repository.GstBase.BaseTransform` sub-classes know the memory ``allocator`` used by the base class and its ``params``. Unref the ``allocator`` after use. .. method:: get_buffer_pool() -> ~gi.repository.Gst.BufferPool | None .. method:: is_in_place() -> bool See if ``trans`` is configured as a in_place transform. .. method:: is_passthrough() -> bool See if ``trans`` is configured as a passthrough transform. .. method:: is_qos_enabled() -> bool Queries if the transform will handle QoS. .. method:: reconfigure() -> bool Negotiates src pad caps with downstream elements if the source pad is marked as needing reconfiguring. Unmarks GST_PAD_FLAG_NEED_RECONFIGURE in any case. But marks it again if negotiation fails. Do not call this in the ``GstBaseTransformClass``::transform or ``GstBaseTransformClass``::transform_ip vmethod. Call this in ``GstBaseTransformClass``::submit_input_buffer, ``GstBaseTransformClass``::prepare_output_buffer or in ``GstBaseTransformClass``::generate_output *before* any output buffer is allocated. It will be default be called when handling an ALLOCATION query or at the very beginning of the default ``GstBaseTransformClass``::submit_input_buffer implementation. .. versionadded:: 1.18 .. method:: reconfigure_sink() -> None Instructs ``trans`` to request renegotiation upstream. This function is typically called after properties on the transform were set that influence the input format. .. method:: reconfigure_src() -> None Instructs ``trans`` to renegotiate a new downstream transform on the next buffer. This function is typically called after properties on the transform were set that influence the output format. .. method:: set_gap_aware(gap_aware: bool) -> None If ``gap_aware`` is :const:`False` (the default), output buffers will have the ``%GST_BUFFER_FLAG_GAP`` flag unset. If set to :const:`True`, the element must handle output buffers with this flag set correctly, i.e. it can assume that the buffer contains neutral data but must unset the flag if the output is no neutral data. MT safe. :param gap_aware: New state .. method:: set_in_place(in_place: bool) -> None Determines whether a non-writable buffer will be copied before passing to the transform_ip function. * Always :const:`True` if no transform function is implemented. * Always :const:`False` if ONLY transform function is implemented. MT safe. :param in_place: Boolean value indicating that we would like to operate on in_place buffers. .. method:: set_passthrough(passthrough: bool) -> None Set passthrough mode for this filter by default. This is mostly useful for filters that do not care about negotiation. Always :const:`True` for filters which don't implement either a transform or transform_ip or generate_output method. MT safe. :param passthrough: boolean indicating passthrough mode. .. method:: set_prefer_passthrough(prefer_passthrough: bool) -> None If ``prefer_passthrough`` is :const:`True` (the default), ``trans`` will check and prefer passthrough caps from the list of caps returned by the transform_caps vmethod. If set to :const:`False`, the element must order the caps returned from the transform_caps function in such a way that the preferred format is first in the list. This can be interesting for transforms that can do passthrough transforms but prefer to do something else, like a capsfilter. MT safe. .. versionadded:: 1.0.1 :param prefer_passthrough: New state .. method:: set_qos_enabled(enabled: bool) -> None Enable or disable QoS handling in the transform. MT safe. :param enabled: new state .. method:: update_qos(proportion: float, diff: int, timestamp: int) -> None Set the QoS parameters in the transform. This function is called internally when a QOS event is received but subclasses can provide custom information when needed. MT safe. :param proportion: the proportion :param diff: the diff against the clock :param timestamp: the timestamp of the buffer generating the QoS expressed in running_time. .. method:: update_src_caps(updated_caps: ~gi.repository.Gst.Caps) -> bool Updates the srcpad caps and sends the caps downstream. This function can be used by subclasses when they have already negotiated their caps but found a change in them (or computed new information). This way, they can notify downstream about that change without losing any buffer. .. versionadded:: 1.6 :param updated_caps: An updated version of the srcpad caps to be pushed downstream Properties ---------- .. rst-class:: interim-class .. class:: BaseTransform :no-index: .. attribute:: props.qos :type: bool Virtual Methods --------------- .. rst-class:: interim-class .. class:: BaseTransform :no-index: .. method:: do_accept_caps(direction: ~gi.repository.Gst.PadDirection, caps: ~gi.repository.Gst.Caps) -> bool Optional. Subclasses can override this method to check if ``caps`` can be handled by the element. The default implementation might not be the most optimal way to check this in all cases. :param direction: :param caps: .. method:: do_before_transform(buffer: ~gi.repository.Gst.Buffer) -> None Optional. This method is called right before the base class will start processing. Dynamic properties or other delayed configuration could be performed in this method. :param buffer: .. method:: do_copy_metadata(input: ~gi.repository.Gst.Buffer, outbuf: ~gi.repository.Gst.Buffer) -> bool Optional. Copy the metadata from the input buffer to the output buffer. The default implementation will copy the flags, timestamps and offsets of the buffer. :param input: :param outbuf: .. method:: do_decide_allocation(query: ~gi.repository.Gst.Query) -> bool Setup the allocation parameters for allocating output buffers. The passed in query contains the result of the downstream allocation query. This function is only called when not operating in passthrough mode. The default implementation will remove all memory dependent metadata. If there is a ``filter_meta`` method implementation, it will be called for all metadata API in the downstream query, otherwise the metadata API is removed. :param query: .. method:: do_filter_meta(query: ~gi.repository.Gst.Query, api: type, params: ~gi.repository.Gst.Structure) -> bool Return :const:`True` if the metadata API should be proposed in the upstream allocation query. The default implementation is :const:`None` and will cause all metadata to be removed. :param query: :param api: :param params: .. method:: do_fixate_caps(direction: ~gi.repository.Gst.PadDirection, caps: ~gi.repository.Gst.Caps, othercaps: ~gi.repository.Gst.Caps) -> ~gi.repository.Gst.Caps :param direction: :param caps: :param othercaps: .. method:: do_generate_output() -> tuple[~gi.repository.Gst.FlowReturn, ~gi.repository.Gst.Buffer] .. method:: do_get_unit_size(caps: ~gi.repository.Gst.Caps) -> tuple[bool, int] :param caps: .. method:: do_prepare_output_buffer(input: ~gi.repository.Gst.Buffer) -> tuple[~gi.repository.Gst.FlowReturn, ~gi.repository.Gst.Buffer] :param input: .. method:: do_propose_allocation(decide_query: ~gi.repository.Gst.Query, query: ~gi.repository.Gst.Query) -> bool Propose buffer allocation parameters for upstream elements. This function must be implemented if the element reads or writes the buffer content. The query that was passed to the decide_allocation is passed in this method (or :const:`None` when the element is in passthrough mode). The default implementation will pass the query downstream when in passthrough mode and will copy all the filtered metadata API in non-passthrough mode. :param decide_query: :param query: .. method:: do_query(direction: ~gi.repository.Gst.PadDirection, query: ~gi.repository.Gst.Query) -> bool Optional. Handle a requested query. Subclasses that implement this must chain up to the parent if they didn't handle the query :param direction: :param query: .. method:: do_set_caps(incaps: ~gi.repository.Gst.Caps, outcaps: ~gi.repository.Gst.Caps) -> bool Allows the subclass to be notified of the actual caps set. :param incaps: :param outcaps: .. method:: do_sink_event(event: ~gi.repository.Gst.Event) -> bool :param event: .. method:: do_src_event(event: ~gi.repository.Gst.Event) -> bool :param event: .. method:: do_start() -> bool Optional. Called when the element starts processing. Allows opening external resources. .. method:: do_stop() -> bool Optional. Called when the element stops processing. Allows closing external resources. .. method:: do_submit_input_buffer(is_discont: bool, input: ~gi.repository.Gst.Buffer) -> ~gi.repository.Gst.FlowReturn Function which accepts a new input buffer and pre-processes it. The default implementation performs caps (re)negotiation, then QoS if needed, and places the input buffer into the ``queued_buf`` member variable. If the buffer is dropped due to QoS, it returns GST_BASE_TRANSFORM_FLOW_DROPPED. If this input buffer is not contiguous with any previous input buffer, then ``is_discont`` is set to :const:`True`. (Since: 1.6) :param is_discont: :param input: .. method:: do_transform(inbuf: ~gi.repository.Gst.Buffer, outbuf: ~gi.repository.Gst.Buffer) -> ~gi.repository.Gst.FlowReturn Required if the element does not operate in-place. Transforms one incoming buffer to one outgoing buffer. The function is allowed to change size/timestamp/duration of the outgoing buffer. :param inbuf: :param outbuf: .. method:: do_transform_caps(direction: ~gi.repository.Gst.PadDirection, caps: ~gi.repository.Gst.Caps, filter: ~gi.repository.Gst.Caps) -> ~gi.repository.Gst.Caps Optional. Given the pad in this direction and the given caps, what caps are allowed on the other pad in this element ? :param direction: :param caps: :param filter: .. method:: do_transform_ip(buf: ~gi.repository.Gst.Buffer) -> ~gi.repository.Gst.FlowReturn Required if the element operates in-place. Transform the incoming buffer in-place. :param buf: .. method:: do_transform_meta(outbuf: ~gi.repository.Gst.Buffer, meta: ~gi.repository.Gst.Meta, inbuf: ~gi.repository.Gst.Buffer) -> bool Optional. Transform the metadata on the input buffer to the output buffer. By default this method copies all meta without tags. Subclasses can implement this method and return :const:`True` if the metadata is to be copied. :param outbuf: :param meta: :param inbuf: .. method:: do_transform_size(direction: ~gi.repository.Gst.PadDirection, caps: ~gi.repository.Gst.Caps, size: int, othercaps: ~gi.repository.Gst.Caps) -> tuple[bool, int] :param direction: :param caps: :param size: :param othercaps: Fields ------ .. rst-class:: interim-class .. class:: BaseTransform :no-index: .. attribute:: element .. attribute:: have_segment .. attribute:: priv .. attribute:: queued_buf .. attribute:: segment .. attribute:: sinkpad .. attribute:: srcpad