--- /dev/null
+/* GStreamer audio filter base class
+ * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
+ * Copyright (C) <2003> David Schleef <ds@schleef.org>
+ * Copyright (C) <2007> Tim-Philipp Müller <tim centricular net>
+ *
+ * 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:gstaudiofilter
+ * @short_description: Base class for simple audio filters
+ *
+ * #GstAudioFilter is a #GstBaseTransform-derived base class for simple audio
+ * filters, ie. those that output the same format that they get as input.
+ *
+ * #GstAudioFilter will parse the input format for you (with error checking)
+ * before calling your setup function. Also, elements deriving from
+ * #GstAudioFilter may use gst_audio_filter_class_add_pad_templates() from
+ * their base_init function to easily configure the set of caps/formats that
+ * the element is able to handle.
+ *
+ * Derived classes should override the #GstAudioFilterClass.setup() and
+ * #GstBaseTransformClass.transform_ip() and/or
+ * #GstBaseTransformClass.transform()
+ * virtual functions in their class_init function.
+ *
+ * Last reviewed on 2007-02-03 (0.10.11.1)
+ *
+ * Since: 0.10.12
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstaudiofilter.h"
+
+#include <string.h>
+
+GST_DEBUG_CATEGORY_STATIC (audiofilter_dbg);
+#define GST_CAT_DEFAULT audiofilter_dbg
+
+static GstStateChangeReturn gst_audio_filter_change_state (GstElement * element,
+ GstStateChange transition);
+static gboolean gst_audio_filter_set_caps (GstBaseTransform * btrans,
+ GstCaps * incaps, GstCaps * outcaps);
+static gboolean gst_audio_filter_get_unit_size (GstBaseTransform * btrans,
+ GstCaps * caps, guint * size);
+
+#define do_init G_STMT_START { \
+ GST_DEBUG_CATEGORY_INIT (audiofilter_dbg, "audiofilter", 0, "audiofilter"); \
+} G_STMT_END
+
+G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GstAudioFilter, gst_audio_filter,
+ GST_TYPE_BASE_TRANSFORM, do_init);
+
+static void
+gst_audio_filter_class_init (GstAudioFilterClass * klass)
+{
+ GstBaseTransformClass *basetrans_class = (GstBaseTransformClass *) klass;
+ GstElementClass *gstelement_class = (GstElementClass *) klass;
+
+ gstelement_class->change_state =
+ GST_DEBUG_FUNCPTR (gst_audio_filter_change_state);
+ basetrans_class->set_caps = GST_DEBUG_FUNCPTR (gst_audio_filter_set_caps);
+ basetrans_class->get_unit_size =
+ GST_DEBUG_FUNCPTR (gst_audio_filter_get_unit_size);
+
+ /* FIXME: Ref the GstRingerBuffer class to get it's debug category
+ * initialized. gst_ring_buffer_parse_caps () which we use later
+ * uses this debug category.
+ */
+ g_type_class_ref (GST_TYPE_RING_BUFFER);
+}
+
+static void
+gst_audio_filter_init (GstAudioFilter * self)
+{
+ /* nothing to do here */
+}
+
+/* we override the state change vfunc here instead of GstBaseTransform's stop
+ * vfunc, so GstAudioFilter-derived elements can override ::stop() for their
+ * own purposes without having to worry about chaining up */
+static GstStateChangeReturn
+gst_audio_filter_change_state (GstElement * element, GstStateChange transition)
+{
+ GstStateChangeReturn ret;
+ GstAudioFilter *filter = GST_AUDIO_FILTER (element);
+
+ switch (transition) {
+ case GST_STATE_CHANGE_NULL_TO_READY:
+ memset (&filter->format, 0, sizeof (GstRingBufferSpec));
+ /* to make gst_buffer_spec_parse_caps() happy */
+ filter->format.latency_time = GST_SECOND;
+ break;
+ default:
+ break;
+ }
+
+ ret =
+ GST_ELEMENT_CLASS (gst_audio_filter_parent_class)->change_state (element,
+ transition);
+ if (ret == GST_STATE_CHANGE_FAILURE)
+ return ret;
+
+ switch (transition) {
+ case GST_STATE_CHANGE_PAUSED_TO_READY:
+ case GST_STATE_CHANGE_READY_TO_NULL:
+ gst_caps_replace (&filter->format.caps, NULL);
+ break;
+ default:
+ break;
+ }
+
+ return ret;
+}
+
+static gboolean
+gst_audio_filter_set_caps (GstBaseTransform * btrans, GstCaps * incaps,
+ GstCaps * outcaps)
+{
+ GstAudioFilterClass *klass;
+ GstAudioFilter *filter = GST_AUDIO_FILTER (btrans);
+ gboolean ret = TRUE;
+
+ GST_LOG_OBJECT (filter, "caps: %" GST_PTR_FORMAT, incaps);
+
+ if (!gst_ring_buffer_parse_caps (&filter->format, incaps)) {
+ GST_WARNING_OBJECT (filter, "couldn't parse %" GST_PTR_FORMAT, incaps);
+ return FALSE;
+ }
+
+ klass = GST_AUDIO_FILTER_CLASS_CAST (G_OBJECT_GET_CLASS (filter));
+
+ if (klass->setup)
+ ret = klass->setup (filter, &filter->format);
+
+ return ret;
+}
+
+static gboolean
+gst_audio_filter_get_unit_size (GstBaseTransform * btrans, GstCaps * caps,
+ guint * size)
+{
+ GstStructure *structure;
+ gboolean ret = TRUE;
+ gint width, channels;
+
+ structure = gst_caps_get_structure (caps, 0);
+
+ ret &= gst_structure_get_int (structure, "width", &width);
+ ret &= gst_structure_get_int (structure, "channels", &channels);
+
+ if (ret)
+ *size = (width / 8) * channels;
+
+ return ret;
+}
+
+/**
+ * gst_audio_filter_class_add_pad_templates:
+ * @klass: an #GstAudioFilterClass
+ * @allowed_caps: what formats the filter can handle, as #GstCaps
+ *
+ * Convenience function to add pad templates to this element class, with
+ * @allowed_caps as the caps that can be handled.
+ *
+ * This function is usually used from within a GObject base_init function.
+ *
+ * Since: 0.10.12
+ */
+void
+gst_audio_filter_class_add_pad_templates (GstAudioFilterClass * klass,
+ const GstCaps * allowed_caps)
+{
+ GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
+ GstPadTemplate *pad_template;
+
+ g_return_if_fail (GST_IS_AUDIO_FILTER_CLASS (klass));
+ g_return_if_fail (GST_IS_CAPS (allowed_caps));
+
+ pad_template = gst_pad_template_new ("src", GST_PAD_SRC, GST_PAD_ALWAYS,
+ gst_caps_copy (allowed_caps));
+ gst_element_class_add_pad_template (element_class, pad_template);
+ gst_object_unref (pad_template);
+
+ pad_template = gst_pad_template_new ("sink", GST_PAD_SINK, GST_PAD_ALWAYS,
+ gst_caps_copy (allowed_caps));
+ gst_element_class_add_pad_template (element_class, pad_template);
+ gst_object_unref (pad_template);
+}
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