text: /* GStreamer
   * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
   *                    2005 Wim Taymans <wim@fluendo.com>
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Library General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Library General Public License for more details.
   *
   * You should have received a copy of the GNU Library General Public
   * License along with this library; if not, write to the
   * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
   * Boston, MA 02110-1301, USA.
   */
  
  #ifndef __GST_BASE_TRANSFORM_H__
  #define __GST_BASE_TRANSFORM_H__
  
  #include <gst/gst.h>
  #include <gst/base/base-prelude.h>
  
  G_BEGIN_DECLS
  
  #define GST_TYPE_BASE_TRANSFORM		   (gst_base_transform_get_type())
  #define GST_BASE_TRANSFORM(obj)		   (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_BASE_TRANSFORM,GstBaseTransform))
  #define GST_BASE_TRANSFORM_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_BASE_TRANSFORM,GstBaseTransformClass))
  #define GST_BASE_TRANSFORM_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS((obj),GST_TYPE_BASE_TRANSFORM,GstBaseTransformClass))
  #define GST_IS_BASE_TRANSFORM(obj)	   (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_BASE_TRANSFORM))
  #define GST_IS_BASE_TRANSFORM_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_BASE_TRANSFORM))
  #define GST_BASE_TRANSFORM_CAST(obj)	((GstBaseTransform *)(obj))
  
  /**
   * GST_BASE_TRANSFORM_SINK_NAME:
   *
   * The name of the templates for the sink pad.
   */
  #define GST_BASE_TRANSFORM_SINK_NAME	"sink"
  /**
   * GST_BASE_TRANSFORM_SRC_NAME:
   *
   * The name of the templates for the source pad.
   */
  #define GST_BASE_TRANSFORM_SRC_NAME	"src"
  
  /**
   * GST_BASE_TRANSFORM_SRC_PAD:
   * @obj: base transform instance
   *
   * Gives the pointer to the source #GstPad object of the element.
   */
  #define GST_BASE_TRANSFORM_SRC_PAD(obj)		(GST_BASE_TRANSFORM_CAST (obj)->srcpad)
  
  /**
   * GST_BASE_TRANSFORM_SINK_PAD:
   * @obj: base transform instance
   *
   * Gives the pointer to the sink #GstPad object of the element.
   */
  #define GST_BASE_TRANSFORM_SINK_PAD(obj)	(GST_BASE_TRANSFORM_CAST (obj)->sinkpad)
  
  /**
   * GST_BASE_TRANSFORM_FLOW_DROPPED:
   *
   * A #GstFlowReturn that can be returned from transform and transform_ip to
   * indicate that no output buffer was generated.
   */
  #define GST_BASE_TRANSFORM_FLOW_DROPPED   GST_FLOW_CUSTOM_SUCCESS
  
  typedef struct _GstBaseTransform GstBaseTransform;
  typedef struct _GstBaseTransformClass GstBaseTransformClass;
  typedef struct _GstBaseTransformPrivate GstBaseTransformPrivate;
  
  /**
   * GstBaseTransform:
   *
   * The opaque #GstBaseTransform data structure.
   */
  struct _GstBaseTransform {
    GstElement	 element;
  
    /*< protected >*/
    /* source and sink pads */
    GstPad	*sinkpad;
    GstPad	*srcpad;
  
    /* MT-protected (with STREAM_LOCK) */
    gboolean       have_segment;
    GstSegment     segment;
    /* Default submit_input_buffer places the buffer here,
     * for consumption by the generate_output method: */
    GstBuffer      *queued_buf;
  
    /*< private >*/
    GstBaseTransformPrivate *priv;
  
    gpointer       _gst_reserved[GST_PADDING_LARGE-1];
  };
  
  /**
   * GstBaseTransformClass:
   * @parent_class:   Element parent class
   * @passthrough_on_same_caps: If set to %TRUE, passthrough mode will be
   *                            automatically enabled if the caps are the same.
   *                            Set to %FALSE by default.
   * @transform_ip_on_passthrough: If set to %TRUE, @transform_ip will be called in
   *                           passthrough mode. The passed buffer might not be
   *                           writable. When %FALSE, neither @transform nor
   *                           @transform_ip will be called in passthrough mode.
   *                           Set to %TRUE by default.
   * @transform_caps: Optional.  Given the pad in this direction and the given
   *                  caps, what caps are allowed on the other pad in this
   *                  element ?
   * @fixate_caps:    Optional. Given the pad in this direction and the given
   *                  caps, fixate the caps on the other pad. The function takes
   *                  ownership of @othercaps and returns a fixated version of
   *                  @othercaps. @othercaps is not guaranteed to be writable.
   * @accept_caps:    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.
   * @set_caps:       allows the subclass to be notified of the actual caps set.
   * @query:          Optional.
   *                  Handle a requested query. Subclasses that implement this
   *                  should must chain up to the parent if they didn't handle the
   *                  query
   * @decide_allocation: 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.
   * @filter_meta: Return %TRUE if the metadata API should be proposed in the
   *               upstream allocation query. The default implementation is %NULL
   *               and will cause all metadata to be removed.
   * @propose_allocation: 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 %NULL
   *                      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.
   * @transform_size: Optional. Given the size of a buffer in the given direction
   *                  with the given caps, calculate the size in bytes of a buffer
   *                  on the other pad with the given other caps.
   *                  The default implementation uses get_unit_size and keeps
   *                  the number of units the same.
   * @get_unit_size:  Required if the transform is not in-place.
   *                  get the size in bytes of one unit for the given caps.
   * @start:          Optional.
   *                  Called when the element starts processing.
   *                  Allows opening external resources.
   * @stop:           Optional.
   *                  Called when the element stops processing.
   *                  Allows closing external resources.
   * @sink_event:     Optional.
   *                  Event handler on the sink pad. The default implementation
   *                  handles the event and forwards it downstream.
   * @src_event:      Optional.
   *                  Event handler on the source pad. The default implementation
   *                  handles the event and forwards it upstream.
   * @prepare_output_buffer: Optional.
   *                         Subclasses can override this to do their own
   *                         allocation of output buffers.  Elements that only do
   *                         analysis can return a subbuffer or even just
   *                         return a reference to the input buffer (if in
   *                         passthrough mode). The default implementation will
   *                         use the negotiated allocator or bufferpool and
   *                         transform_size to allocate an output buffer or it
   *                         will return the input buffer in passthrough mode.
   * @copy_metadata: 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.
   * @transform_meta: 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 %TRUE if
   *                  the metadata is to be copied.
   * @before_transform: 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.
   * @transform:      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.
   * @transform_ip:   Required if the element operates in-place.
   *                  Transform the incoming buffer in-place.
   * @submit_input_buffer: 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 %TRUE. (Since 1.6)
   * @generate_output: Called after each new input buffer is submitted repeatedly
   *                   until it either generates an error or fails to generate an output
   *                   buffer. The default implementation takes the contents of the
   *                   @queued_buf variable, generates an output buffer if needed
   *                   by calling the class @prepare_output_buffer, and then
   *                   calls either @transform or @transform_ip. Elements that don't
   *                   do 1-to-1 transformations on input to output buffers can either
   *                   return GST_BASE_TRANSFORM_FLOW_DROPPED or simply not generate
   *                   an output buffer until they are ready to do so. (Since 1.6)
   *
   * Subclasses can override any of the available virtual methods or not, as
   * needed. At minimum either @transform or @transform_ip need to be overridden.
   * If the element can overwrite the input data with the results (data is of the
   * same type and quantity) it should provide @transform_ip.
   */
  struct _GstBaseTransformClass {
    GstElementClass parent_class;
  
    /*< public >*/
    gboolean       passthrough_on_same_caps;
    gboolean       transform_ip_on_passthrough;
  
    /* virtual methods for subclasses */
    GstCaps*	(*transform_caps) (GstBaseTransform *trans,
                                     GstPadDirection direction,
                                     GstCaps *caps, GstCaps *filter);
    GstCaps*	(*fixate_caps)	  (GstBaseTransform *trans,
                                     GstPadDirection direction, GstCaps *caps,
                                     GstCaps *othercaps);
    gboolean      (*accept_caps)    (GstBaseTransform *trans, GstPadDirection direction,
                                     GstCaps *caps);
    gboolean      (*set_caps)       (GstBaseTransform *trans, GstCaps *incaps,
                                     GstCaps *outcaps);
    gboolean      (*query)          (GstBaseTransform *trans, GstPadDirection direction,
                                     GstQuery *query);
  
    /* decide allocation query for output buffers */
    gboolean      (*decide_allocation)  (GstBaseTransform *trans, GstQuery *query);
    gboolean      (*filter_meta)        (GstBaseTransform *trans, GstQuery *query,
                                         GType api, const GstStructure *params);
  
    /* propose allocation query parameters for input buffers */
    gboolean      (*propose_allocation) (GstBaseTransform *trans, GstQuery *decide_query,
                                         GstQuery *query);
  
    /**
     * GstBaseTransformClass::transform_size:
     * @othersize: (out):
     */
    gboolean      (*transform_size) (GstBaseTransform *trans,
                                     GstPadDirection direction,
                                     GstCaps *caps, gsize size,
                                     GstCaps *othercaps, gsize *othersize);
  
    /**
     * GstBaseTransformClass::get_unit_size:
     * @size: (out):
     */
    gboolean      (*get_unit_size)  (GstBaseTransform *trans, GstCaps *caps,
                                     gsize *size);
  
    /* states */
    gboolean      (*start)        (GstBaseTransform *trans);
    gboolean      (*stop)         (GstBaseTransform *trans);
  
    /* sink and src pad event handlers */
    gboolean      (*sink_event)   (GstBaseTransform *trans, GstEvent *event);
    gboolean      (*src_event)    (GstBaseTransform *trans, GstEvent *event);
  
    /**
     * GstBaseTransformClass::prepare_output_buffer:
     * @outbuf: (out):
     */
    GstFlowReturn (*prepare_output_buffer) (GstBaseTransform * trans,
                                            GstBuffer *input, GstBuffer **outbuf);
  
    /* metadata */
    gboolean      (*copy_metadata)     (GstBaseTransform *trans, GstBuffer *input,
                                        GstBuffer *outbuf);
    gboolean      (*transform_meta)    (GstBaseTransform *trans, GstBuffer *outbuf,
                                        GstMeta *meta, GstBuffer *inbuf);
  
    void          (*before_transform)  (GstBaseTransform *trans, GstBuffer *buffer);
  
    /* transform */
    GstFlowReturn (*transform)    (GstBaseTransform *trans, GstBuffer *inbuf,
                                   GstBuffer *outbuf);
    GstFlowReturn (*transform_ip) (GstBaseTransform *trans, GstBuffer *buf);
  
    GstFlowReturn (*submit_input_buffer) (GstBaseTransform *trans, gboolean is_discont, GstBuffer *input);
  
    /**
     * GstBaseTransformClass::generate_output:
     * @outbuf: (out):
     */
    GstFlowReturn (*generate_output) (GstBaseTransform *trans, GstBuffer **outbuf);
  
    /*< private >*/
    gpointer       _gst_reserved[GST_PADDING_LARGE - 2];
  };
  
  GST_BASE_API
  GType           gst_base_transform_get_type         (void);
  
  GST_BASE_API
  void		gst_base_transform_set_passthrough  (GstBaseTransform *trans,
  	                                             gboolean passthrough);
  GST_BASE_API
  gboolean	gst_base_transform_is_passthrough   (GstBaseTransform *trans);
  
  GST_BASE_API
  void		gst_base_transform_set_in_place     (GstBaseTransform *trans,
  	                                             gboolean in_place);
  GST_BASE_API
  gboolean	gst_base_transform_is_in_place      (GstBaseTransform *trans);
  
  GST_BASE_API
  void		gst_base_transform_update_qos       (GstBaseTransform *trans,
  						     gdouble proportion,
  						     GstClockTimeDiff diff,
  						     GstClockTime timestamp);
  GST_BASE_API
  void		gst_base_transform_set_qos_enabled  (GstBaseTransform *trans,
  		                                     gboolean enabled);
  GST_BASE_API
  gboolean	gst_base_transform_is_qos_enabled   (GstBaseTransform *trans);
  
  GST_BASE_API
  void            gst_base_transform_set_gap_aware    (GstBaseTransform *trans,
                                                       gboolean gap_aware);
  GST_BASE_API
  void            gst_base_transform_set_prefer_passthrough (GstBaseTransform *trans,
                                                             gboolean prefer_passthrough);
  GST_BASE_API
  GstBufferPool * gst_base_transform_get_buffer_pool  (GstBaseTransform *trans);
  
  GST_BASE_API
  void            gst_base_transform_get_allocator    (GstBaseTransform *trans,
                                                       GstAllocator **allocator,
                                                       GstAllocationParams *params);
  GST_BASE_API
  void		gst_base_transform_reconfigure_sink (GstBaseTransform *trans);
  
  GST_BASE_API
  void		gst_base_transform_reconfigure_src  (GstBaseTransform *trans);
  
  GST_BASE_API
  gboolean gst_base_transform_update_src_caps (GstBaseTransform *trans,
                                               GstCaps *updated_caps);
  
  #ifdef G_DEFINE_AUTOPTR_CLEANUP_FUNC
  G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstBaseTransform, gst_object_unref)
  #endif
  
  G_END_DECLS
  
  #endif /* __GST_BASE_TRANSFORM_H__ */
  