gstbasetransform.c

gnash 在pc和嵌入式下开发需要的源码

/* GStreamer
 * Copyright (C) 1999,2000 Erik Walthinsen <[e-mail]>
 *                    2000 Wim Taymans <[e-mail]>
 *                    2005 Wim Taymans <[e-mail]>
 *                    2005 Andy Wingo <[e-mail]>
 *                    2005 Thomas Vander Stichele <thomas at apestaart dot org>
 *
 * 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., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/**
 * SECTION:gstbasetransform
 * @short_description: Base class for simple transform filters
 * @see_also: #GstBaseSrc, #GstBaseSink
 *
 * This base class is for filter elements that process data.
 *
 * It provides for:
 * <itemizedlist>
 *   <listitem><para>one sinkpad and one srcpad</para></listitem>
 *   <listitem><para>
 *      Possible formats on sink and source pad implemented
 *      with custom transform_caps function. By default uses
 *      same format on sink and source.
 *   </para></listitem>
 *   <listitem><para>Handles state changes</para></listitem>
 *   <listitem><para>Does flushing</para></listitem>
 *   <listitem><para>Push mode</para></listitem>
 *   <listitem><para>
 *       Pull mode if the sub-class transform can operate on arbitrary data
 *    </para></listitem>
 * </itemizedlist>
 *
 * Use Cases:
 * <orderedlist>
 * <listitem>
 *   <itemizedlist><title>Passthrough mode</title>
 *   <listitem><para>
 *     Element has no interest in modifying the buffer. It may want to inspect it,
 *     in which case the element should have a transform_ip function. If there
 *     is no transform_ip function in passthrough mode, the buffer is pushed
 *     intact.
 *   </para></listitem>
 *   <listitem><para>
 *     On the GstBaseTransformClass is the passthrough_on_same_caps variable
 *     which will automatically set/unset passthrough based on whether the
 *     element negotiates the same caps on both pads.
 *   </para></listitem>
 *   <listitem><para>
 *     passthrough_on_same_caps on an element that doesn't implement a
 *     transform_caps function is useful for elements that only inspect data
 *     (such as level)
 *   </para></listitem>
 *   </itemizedlist>
 *   <itemizedlist>
 *   <title>Example elements</title>
 *     <listitem>Level</listitem>
 *     <listitem>Videoscale, audioconvert, ffmpegcolorspace, audioresample in
 *     certain modes.</listitem>
 *   </itemizedlist>
 * </listitem>
 * <listitem>
 *   <itemizedlist>
 *     <title>Modifications in-place - input buffer and output buffer are the
 *     same thing.</title>
 *   <listitem><para>
 *     The element must implement a transform_ip function.
 *   </para></listitem>
 *   <listitem><para>
 *     Output buffer size must <= input buffer size
 *   </para></listitem>
 *   <listitem><para>
 *     If the always_in_place flag is set, non-writable buffers will be copied
 *     and passed to the transform_ip function, otherwise a new buffer will be
 *     created and the transform function called.
 *   </para></listitem>
 *   <listitem><para>
 *     Incoming writable buffers will be passed to the transform_ip function
 *     immediately.  </para></listitem>
 *   <listitem><para>
 *     only implementing transform_ip and not transform implies always_in_place
 *     = TRUE
 *   </para></listitem>
 *   </itemizedlist>
 *   <itemizedlist>
 *   <title>Example elements</title>
 *     <listitem>Volume</listitem>
 *     <listitem>Audioconvert in certain modes (signed/unsigned
 *     conversion)</listitem>
 *     <listitem>ffmpegcolorspace in certain modes (endianness
 *     swapping)</listitem>
 *   </itemizedlist>
 *  </listitem>
 * <listitem>
 *   <itemizedlist>
 *   <title>Modifications only to the caps/metadata of a buffer</title>
 *   <listitem><para>
 *     The element does not require writable data, but non-writable buffers
 *     should be subbuffered so that the meta-information can be replaced.
 *   </para></listitem>
 *   <listitem><para>
 *     Elements wishing to operate in this mode should replace the
 *     prepare_output_buffer method to create subbuffers of the input buffer
 *     and set always_in_place to TRUE
 *   </para></listitem>
 *   </itemizedlist>
 *   <itemizedlist>
 *   <title>Example elements</title>
 *     <listitem>Capsfilter when setting caps on outgoing buffers that have
 *     none.</listitem>
 *     <listitem>identity when it is going to re-timestamp buffers by
 *     datarate.</listitem>
 *   </itemizedlist>
 * </listitem>
 * <listitem>
 *   <itemizedlist><title>Normal mode</title>
 *   <listitem><para>
 *     always_in_place flag is not set, or there is no transform_ip function
 *   </para></listitem>
 *   <listitem><para>
 *     Element will receive an input buffer and output buffer to operate on.
 *   </para></listitem>
 *   <listitem><para>
 *     Output buffer is allocated by calling the prepare_output_buffer function.
 *   </para></listitem>
 *   </itemizedlist>
 *   <itemizedlist>
 *   <title>Example elements</title>
 *     <listitem>Videoscale, ffmpegcolorspace, audioconvert when doing
 *     scaling/conversions</listitem>
 *   </itemizedlist>
 * </listitem>
 * <listitem>
 *   <itemizedlist><title>Special output buffer allocations</title>
 *   <listitem><para>
 *     Elements which need to do special allocation of their output buffers
 *     other than what gst_buffer_pad_alloc allows should implement a
 *     prepare_output_buffer method, which calls the parent implementation and
 *     passes the newly allocated buffer.
 *   </para></listitem>
 *   </itemizedlist>
 *   <itemizedlist>
 *   <title>Example elements</title>
 *     <listitem>efence</listitem>
 *   </itemizedlist>
 * </listitem>
 * </orderedlist>
 *
 * <itemizedlist><title>Sub-class settable flags on GstBaseTransform</title>
 * <listitem><para>
 *   <itemizedlist><title>passthrough</title>
 *     <listitem><para>
 *       Implies that in the current configuration, the sub-class is not
 *       interested in modifying the buffers.
 *     </para></listitem>
 *     <listitem><para>
 *       Elements which are always in passthrough mode whenever the same caps
 *       has been negotiated on both pads can set the class variable
 *       passthrough_on_same_caps to have this behaviour automatically.
 *     </para></listitem>
 *   </itemizedlist>
 * </para></listitem>
 * <listitem><para>
 *   <itemizedlist><title>always_in_place</title>
 *     <listitem><para>
 *       Determines whether a non-writable buffer will be copied before passing
 *       to the transform_ip function.
 *     </para></listitem>
 *     <listitem><para>
 *       Implied TRUE if no transform function is implemented.
 *     </para></listitem>
 *     <listitem><para>
 *       Implied FALSE if ONLY transform function is implemented.
 *     </para></listitem>
 *   </itemizedlist>
 * </para></listitem>
 * </itemizedlist>
 *
*/

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <stdlib.h>
#include <string.h>

#include "../../../gst/gst_private.h"
#include "../../../gst/gst-i18n-lib.h"
#include "gstbasetransform.h"
#include <gst/gstmarshal.h>

GST_DEBUG_CATEGORY_STATIC (gst_base_transform_debug);
#define GST_CAT_DEFAULT gst_base_transform_debug

/* BaseTransform signals and args */
enum
{
  /* FILL ME */
  LAST_SIGNAL
};

#define DEFAULT_PROP_QOS	FALSE

enum
{
  PROP_0,
  PROP_QOS
};

#define GST_BASE_TRANSFORM_GET_PRIVATE(obj)  \
    (G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_BASE_TRANSFORM, GstBaseTransformPrivate))

struct _GstBaseTransformPrivate
{
  /* QoS *//* with LOCK */
  gboolean qos_enabled;
  gdouble proportion;
  GstClockTime earliest_time;
  /* previous buffer had a discont */
  gboolean discont;

  GstActivateMode pad_mode;
};

static GstElementClass *parent_class = NULL;

static void gst_base_transform_base_init (gpointer g_class);
static void gst_base_transform_class_init (GstBaseTransformClass * klass);
static void gst_base_transform_init (GstBaseTransform * trans,
    GstBaseTransformClass * klass);
static GstFlowReturn gst_base_transform_prepare_output_buffer (GstBaseTransform
    * trans, GstBuffer * input, gint size, GstCaps * caps, GstBuffer ** buf);

GType
gst_base_transform_get_type (void)
{
  static GType base_transform_type = 0;

  if (!base_transform_type) {
    static const GTypeInfo base_transform_info = {
      sizeof (GstBaseTransformClass),
      (GBaseInitFunc) gst_base_transform_base_init,
      NULL,
      (GClassInitFunc) gst_base_transform_class_init,
      NULL,
      NULL,
      sizeof (GstBaseTransform),
      0,
      (GInstanceInitFunc) gst_base_transform_init,
    };

    base_transform_type = g_type_register_static (GST_TYPE_ELEMENT,
        "GstBaseTransform", &base_transform_info, G_TYPE_FLAG_ABSTRACT);
  }
  return base_transform_type;
}

static void gst_base_transform_finalize (GObject * object);
static void gst_base_transform_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec);
static void gst_base_transform_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec);
static gboolean gst_base_transform_src_activate_pull (GstPad * pad,
    gboolean active);
static gboolean gst_base_transform_sink_activate_push (GstPad * pad,
    gboolean active);
static gboolean gst_base_transform_activate (GstBaseTransform * trans,
    gboolean active);
static gboolean gst_base_transform_get_unit_size (GstBaseTransform * trans,
    GstCaps * caps, guint * size);

static gboolean gst_base_transform_src_event (GstPad * pad, GstEvent * event);
static gboolean gst_base_transform_src_eventfunc (GstBaseTransform * trans,
    GstEvent * event);
static gboolean gst_base_transform_sink_event (GstPad * pad, GstEvent * event);
static gboolean gst_base_transform_sink_eventfunc (GstBaseTransform * trans,
    GstEvent * event);
static gboolean gst_base_transform_check_get_range (GstPad * pad);
static GstFlowReturn gst_base_transform_getrange (GstPad * pad, guint64 offset,
    guint length, GstBuffer ** buffer);
static GstFlowReturn gst_base_transform_chain (GstPad * pad,
    GstBuffer * buffer);
static GstCaps *gst_base_transform_getcaps (GstPad * pad);
static gboolean gst_base_transform_setcaps (GstPad * pad, GstCaps * caps);
static GstFlowReturn gst_base_transform_buffer_alloc (GstPad * pad,
    guint64 offset, guint size, GstCaps * caps, GstBuffer ** buf);

/* static guint gst_base_transform_signals[LAST_SIGNAL] = { 0 }; */

static void
gst_base_transform_base_init (gpointer g_class)
{
  GST_DEBUG_CATEGORY_INIT (gst_base_transform_debug, "basetransform", 0,
      "basetransform element");
}

static void
gst_base_transform_finalize (GObject * object)
{
  GstBaseTransform *trans;

  trans = GST_BASE_TRANSFORM (object);

  g_mutex_free (trans->transform_lock);

  G_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
gst_base_transform_class_init (GstBaseTransformClass * klass)
{
  GObjectClass *gobject_class;

  gobject_class = G_OBJECT_CLASS (klass);

  g_type_class_add_private (klass, sizeof (GstBaseTransformPrivate));

  parent_class = g_type_class_peek_parent (klass);

  gobject_class->set_property =
      GST_DEBUG_FUNCPTR (gst_base_transform_set_property);
  gobject_class->get_property =
      GST_DEBUG_FUNCPTR (gst_base_transform_get_property);

  g_object_class_install_property (gobject_class, PROP_QOS,
      g_param_spec_boolean ("qos", "QoS", "handle QoS messages",
          DEFAULT_PROP_QOS, G_PARAM_READWRITE));

  gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_base_transform_finalize);

  klass->passthrough_on_same_caps = FALSE;
  klass->event = GST_DEBUG_FUNCPTR (gst_base_transform_sink_eventfunc);
  klass->src_event = GST_DEBUG_FUNCPTR (gst_base_transform_src_eventfunc);
}

static void
gst_base_transform_init (GstBaseTransform * trans,
    GstBaseTransformClass * bclass)
{
  GstPadTemplate *pad_template;

  GST_DEBUG ("gst_base_transform_init");

  trans->priv = GST_BASE_TRANSFORM_GET_PRIVATE (trans);

  pad_template =
      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (bclass), "sink");
  g_return_if_fail (pad_template != NULL);
  trans->sinkpad = gst_pad_new_from_template (pad_template, "sink");
  gst_pad_set_getcaps_function (trans->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_getcaps));
  gst_pad_set_setcaps_function (trans->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_setcaps));
  gst_pad_set_event_function (trans->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_sink_event));
  gst_pad_set_chain_function (trans->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_chain));
  gst_pad_set_activatepush_function (trans->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_sink_activate_push));
  gst_pad_set_bufferalloc_function (trans->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_buffer_alloc));
  gst_element_add_pad (GST_ELEMENT (trans), trans->sinkpad);

  pad_template =
      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (bclass), "src");
  g_return_if_fail (pad_template != NULL);
  trans->srcpad = gst_pad_new_from_template (pad_template, "src");
  gst_pad_set_getcaps_function (trans->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_getcaps));
  gst_pad_set_setcaps_function (trans->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_setcaps));
  gst_pad_set_event_function (trans->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_src_event));
  gst_pad_set_checkgetrange_function (trans->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_check_get_range));
  gst_pad_set_getrange_function (trans->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_getrange));
  gst_pad_set_activatepull_function (trans->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_transform_src_activate_pull));
  gst_element_add_pad (GST_ELEMENT (trans), trans->srcpad);

  trans->transform_lock = g_mutex_new ();
  trans->delay_configure = FALSE;
  trans->pending_configure = FALSE;
  trans->priv->qos_enabled = DEFAULT_PROP_QOS;
  trans->cache_caps1 = NULL;
  trans->cache_caps2 = NULL;
  trans->priv->pad_mode = GST_ACTIVATE_NONE;

  trans->passthrough = FALSE;
  if (bclass->transform == NULL) {
    /* If no transform function, always_in_place is TRUE */
    GST_DEBUG_OBJECT (trans, "setting in_place TRUE");
    trans->always_in_place = TRUE;

    if (bclass->transform_ip == NULL)
      trans->passthrough = TRUE;
  }
}

/* given @caps on the src or sink pad (given by @direction)
 * calculate the possible caps on the other pad.
 *
 * Returns new caps, unref after usage.
 */
static GstCaps *
gst_base_transform_transform_caps (GstBaseTransform * trans,
    GstPadDirection direction, GstCaps * caps)
{
  GstCaps *ret;
  GstBaseTransformClass *klass;

  klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

  /* if there is a custom transform function, use this */
  if (klass->transform_caps) {
    GstCaps *temp;
    gint i;

    /* start with empty caps */
    ret = gst_caps_new_empty ();
    GST_DEBUG_OBJECT (trans, "transform caps (direction = %d)", direction);

    if (gst_caps_is_any (caps)) {
      /* for any caps we still have to call the transform function */
      GST_DEBUG_OBJECT (trans, "from: ANY");
      temp = klass->transform_caps (trans, direction, caps);
      GST_DEBUG_OBJECT (trans, "  to: %" GST_PTR_FORMAT, temp);

      temp = gst_caps_make_writable (temp);
      gst_caps_append (ret, temp);
    } else {
      /* we send caps with just one structure to the transform
       * function as this is easier for the element */
      for (i = 0; i < gst_caps_get_size (caps); i++) {
        GstCaps *nth;

        nth = gst_caps_copy_nth (caps, i);
        GST_DEBUG_OBJECT (trans, "from[%d]: %" GST_PTR_FORMAT, i, nth);
        temp = klass->transform_caps (trans, direction, nth);
        gst_caps_unref (nth);
        GST_DEBUG_OBJECT (trans, "  to[%d]: %" GST_PTR_FORMAT, i, temp);

        temp = gst_caps_make_writable (temp);
        /* FIXME: here we need to only append those structures, that are not yet
         * in there
         * gst_caps_append (ret, temp);
         */
        gst_caps_merge (ret, temp);
      }
      GST_DEBUG_OBJECT (trans, "merged: (%d)", gst_caps_get_size (ret));
      /* now simplify caps
         gst_caps_do_simplify (ret);
         GST_DEBUG_OBJECT (trans, "simplified: (%d)", gst_caps_get_size (ret));
       */
    }
  } else {
    /* else use the identity transform */
    ret = gst_caps_ref (caps);
  }

  GST_DEBUG_OBJECT (trans, "to: (%d) %" GST_PTR_FORMAT, gst_caps_get_size (ret),
      ret);

  return ret;
}

static gboolean
gst_base_transform_transform_size (GstBaseTransform * trans,
    GstPadDirection direction, GstCaps * caps,
    guint size, GstCaps * othercaps, guint * othersize)
{
  guint inunitsize, outunitsize, units;
  GstBaseTransformClass *klass;