gstreamer/libs/gst/base/gstpushsrc.c
2011-04-19 11:45:36 +02:00

116 lines
3.4 KiB
C

/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000,2005 Wim Taymans <wim@fluendo.com>
*
* gstpushsrc.c:
*
* 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:gstpushsrc
* @short_description: Base class for push based source elements
* @see_also: #GstBaseSrc
*
* This class is mostly useful for elements that cannot do
* random access, or at least very slowly. The source usually
* prefers to push out a fixed size buffer.
*
* Subclasses usually operate in a format that is different from the
* default GST_FORMAT_BYTES format of #GstBaseSrc.
*
* Classes extending this base class will usually be scheduled
* in a push based mode. If the peer accepts to operate without
* offsets and within the limits of the allowed block size, this
* class can operate in getrange based mode automatically. To make
* this possible, the subclass should override the ::check_get_range
* method.
*
* The subclass should extend the methods from the baseclass in
* addition to the ::create method.
*
* Seeking, flushing, scheduling and sync is all handled by this
* base class.
*
* Last reviewed on 2006-07-04 (0.10.9)
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdlib.h>
#include <string.h>
#include "gstpushsrc.h"
#include "gsttypefindhelper.h"
#include <gst/gstmarshal.h>
GST_DEBUG_CATEGORY_STATIC (gst_push_src_debug);
#define GST_CAT_DEFAULT gst_push_src_debug
#define _do_init \
GST_DEBUG_CATEGORY_INIT (gst_push_src_debug, "pushsrc", 0, \
"pushsrc element");
#define gst_push_src_parent_class parent_class
G_DEFINE_TYPE_WITH_CODE (GstPushSrc, gst_push_src, GST_TYPE_BASE_SRC, _do_init);
static gboolean gst_push_src_check_get_range (GstBaseSrc * src);
static GstFlowReturn gst_push_src_create (GstBaseSrc * bsrc, guint64 offset,
guint length, GstBuffer ** ret);
static void
gst_push_src_class_init (GstPushSrcClass * klass)
{
GstBaseSrcClass *gstbasesrc_class = (GstBaseSrcClass *) klass;
gstbasesrc_class->create = GST_DEBUG_FUNCPTR (gst_push_src_create);
gstbasesrc_class->check_get_range =
GST_DEBUG_FUNCPTR (gst_push_src_check_get_range);
}
static void
gst_push_src_init (GstPushSrc * pushsrc)
{
/* nop */
}
static gboolean
gst_push_src_check_get_range (GstBaseSrc * src)
{
/* a pushsrc can by default never operate in pull mode override
* if you want something different. */
return FALSE;
}
static GstFlowReturn
gst_push_src_create (GstBaseSrc * bsrc, guint64 offset, guint length,
GstBuffer ** ret)
{
GstFlowReturn fret;
GstPushSrc *src;
GstPushSrcClass *pclass;
src = GST_PUSH_SRC (bsrc);
pclass = GST_PUSH_SRC_GET_CLASS (src);
if (pclass->create)
fret = pclass->create (src, ret);
else
fret = GST_FLOW_ERROR;
return fret;
}