sys/osxaudio/gstosxaudiosrc.c - imx-gst-plugins-good - Git at Google

 /*
  * GStreamer
  * Copyright (C) 2005,2006 Zaheer Abbas Merali <zaheerabbas at merali dot org>
  * Copyright (C) 2008 Pioneers of the Inevitable <songbird@songbirdnest.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  *
  * Alternatively, the contents of this file may be used under the
  * GNU Lesser General Public License Version 2.1 (the "LGPL"), in
  * which case the following provisions apply instead of the ones
  * mentioned above:
  *
  * 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.
  */

 /**
  * SECTION:element-osxaudiosrc
  *
  * This element captures raw audio samples using the CoreAudio api.
  *
  * <refsect2>
  * <title>Example launch line</title>
  * |[
  * gst-launch-1.0 osxaudiosrc ! wavenc ! filesink location=audio.wav
  * ]|
  * </refsect2>
  */

 #ifdef HAVE_CONFIG_H
 #  include <config.h>
 #endif

 #include <gst/gst.h>
 #include "gstosxaudiosrc.h"
 #include "gstosxaudioelement.h"

 GST_DEBUG_CATEGORY_STATIC (osx_audiosrc_debug);
 #define GST_CAT_DEFAULT osx_audiosrc_debug

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

 enum
 {
   ARG_0,
   ARG_DEVICE
 };

 static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS (GST_OSX_AUDIO_SRC_CAPS)
     );

 static void gst_osx_audio_src_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec);
 static void gst_osx_audio_src_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec);

 static GstStateChangeReturn
 gst_osx_audio_src_change_state (GstElement * element,
     GstStateChange transition);

 static GstCaps *gst_osx_audio_src_get_caps (GstBaseSrc * src, GstCaps * filter);

 static GstAudioRingBuffer *gst_osx_audio_src_create_ringbuffer (GstAudioBaseSrc
     * src);
 static void gst_osx_audio_src_osxelement_init (gpointer g_iface,
     gpointer iface_data);
 static OSStatus gst_osx_audio_src_io_proc (GstOsxAudioRingBuffer * buf,
     AudioUnitRenderActionFlags * ioActionFlags,
     const AudioTimeStamp * inTimeStamp, UInt32 inBusNumber,
     UInt32 inNumberFrames, AudioBufferList * bufferList);

 static void
 gst_osx_audio_src_do_init (GType type)
 {
   static const GInterfaceInfo osxelement_info = {
     gst_osx_audio_src_osxelement_init,
     NULL,
     NULL
   };

   GST_DEBUG_CATEGORY_INIT (osx_audiosrc_debug, "osxaudiosrc", 0,
       "OSX Audio Src");
   g_type_add_interface_static (type, GST_OSX_AUDIO_ELEMENT_TYPE,
       &osxelement_info);
 }

 #define gst_osx_audio_src_parent_class parent_class
 G_DEFINE_TYPE_WITH_CODE (GstOsxAudioSrc, gst_osx_audio_src,
     GST_TYPE_AUDIO_BASE_SRC, gst_osx_audio_src_do_init (g_define_type_id));

 static void
 gst_osx_audio_src_class_init (GstOsxAudioSrcClass * klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *gstelement_class;
   GstBaseSrcClass *gstbasesrc_class;
   GstAudioBaseSrcClass *gstaudiobasesrc_class;

   gobject_class = (GObjectClass *) klass;
   gstelement_class = (GstElementClass *) klass;
   gstbasesrc_class = (GstBaseSrcClass *) klass;
   gstaudiobasesrc_class = (GstAudioBaseSrcClass *) klass;

   gobject_class->set_property = gst_osx_audio_src_set_property;
   gobject_class->get_property = gst_osx_audio_src_get_property;

   gstelement_class->change_state =
       GST_DEBUG_FUNCPTR (gst_osx_audio_src_change_state);

   gstbasesrc_class->get_caps = GST_DEBUG_FUNCPTR (gst_osx_audio_src_get_caps);

   g_object_class_install_property (gobject_class, ARG_DEVICE,
       g_param_spec_int ("device", "Device ID", "Device ID of input device",
           0, G_MAXINT, 0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   gstaudiobasesrc_class->create_ringbuffer =
       GST_DEBUG_FUNCPTR (gst_osx_audio_src_create_ringbuffer);

   gst_element_class_add_static_pad_template (gstelement_class, &src_factory);

   gst_element_class_set_static_metadata (gstelement_class, "Audio Source (OSX)",
       "Source/Audio",
       "Input from a sound card in OS X",
       "Zaheer Abbas Merali <zaheerabbas at merali dot org>");
 }

 static void
 gst_osx_audio_src_init (GstOsxAudioSrc * src)
 {
   gst_base_src_set_live (GST_BASE_SRC (src), TRUE);

   src->device_id = kAudioDeviceUnknown;
 }

 static void
 gst_osx_audio_src_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec)
 {
   GstOsxAudioSrc *src = GST_OSX_AUDIO_SRC (object);

   switch (prop_id) {
     case ARG_DEVICE:
       src->device_id = g_value_get_int (value);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static void
 gst_osx_audio_src_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec)
 {
   GstOsxAudioSrc *src = GST_OSX_AUDIO_SRC (object);

   switch (prop_id) {
     case ARG_DEVICE:
       g_value_set_int (value, src->device_id);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static GstStateChangeReturn
 gst_osx_audio_src_change_state (GstElement * element, GstStateChange transition)
 {
   GstOsxAudioSrc *osxsrc = GST_OSX_AUDIO_SRC (element);
   GstOsxAudioRingBuffer *ringbuffer;
   GstStateChangeReturn ret;

   switch (transition) {
     default:
       break;
   }

   ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
   if (ret == GST_STATE_CHANGE_FAILURE)
     goto out;

   switch (transition) {
     case GST_STATE_CHANGE_NULL_TO_READY:
       /* The device is open now, so fix our device_id if it changed */
       ringbuffer =
           GST_OSX_AUDIO_RING_BUFFER (GST_AUDIO_BASE_SRC (osxsrc)->ringbuffer);
       if (ringbuffer->core_audio->device_id != osxsrc->device_id) {
         osxsrc->device_id = ringbuffer->core_audio->device_id;
         g_object_notify (G_OBJECT (osxsrc), "device");
       }
       break;

     default:
       break;
   }

 out:
   return ret;
 }

 static GstCaps *
 gst_osx_audio_src_get_caps (GstBaseSrc * src, GstCaps * filter)
 {
   GstOsxAudioSrc *osxsrc;
   GstAudioRingBuffer *buf;
   GstOsxAudioRingBuffer *osxbuf;
   GstCaps *caps, *filtered_caps;

   osxsrc = GST_OSX_AUDIO_SRC (src);

   GST_OBJECT_LOCK (osxsrc);
   buf = GST_AUDIO_BASE_SRC (src)->ringbuffer;
   if (buf)
     gst_object_ref (buf);
   GST_OBJECT_UNLOCK (osxsrc);

   if (!buf) {
     GST_DEBUG_OBJECT (src, "no ring buffer, using template caps");
     return GST_BASE_SRC_CLASS (parent_class)->get_caps (src, filter);
   }

   osxbuf = GST_OSX_AUDIO_RING_BUFFER (buf);

   /* protect against cached_caps going away */
   GST_OBJECT_LOCK (buf);

   if (osxbuf->core_audio->cached_caps_valid) {
     GST_LOG_OBJECT (src, "Returning cached caps");
     caps = gst_caps_ref (osxbuf->core_audio->cached_caps);
   } else if (buf->open) {
     GstCaps *template_caps;

     /* Get template caps */
     template_caps =
         gst_pad_get_pad_template_caps (GST_AUDIO_BASE_SRC_PAD (osxsrc));

     /* Device is open, let's probe its caps */
     caps = gst_core_audio_probe_caps (osxbuf->core_audio, template_caps);
     gst_caps_replace (&osxbuf->core_audio->cached_caps, caps);

     gst_caps_unref (template_caps);
   } else {
     GST_DEBUG_OBJECT (src, "ring buffer not open, using template caps");
     caps = GST_BASE_SRC_CLASS (parent_class)->get_caps (src, NULL);
   }

   GST_OBJECT_UNLOCK (buf);

   gst_object_unref (buf);

   if (!caps)
     return NULL;

   if (!filter)
     return caps;

   /* Take care of filtered caps */
   filtered_caps =
       gst_caps_intersect_full (filter, caps, GST_CAPS_INTERSECT_FIRST);
   gst_caps_unref (caps);
   return filtered_caps;
 }

 static GstAudioRingBuffer *
 gst_osx_audio_src_create_ringbuffer (GstAudioBaseSrc * src)
 {
   GstOsxAudioSrc *osxsrc;
   GstOsxAudioRingBuffer *ringbuffer;

   osxsrc = GST_OSX_AUDIO_SRC (src);

   GST_DEBUG_OBJECT (osxsrc, "Creating ringbuffer");
   ringbuffer = g_object_new (GST_TYPE_OSX_AUDIO_RING_BUFFER, NULL);
   GST_DEBUG_OBJECT (osxsrc, "osx src 0x%p element 0x%p  ioproc 0x%p", osxsrc,
       GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsrc),
       (void *) gst_osx_audio_src_io_proc);

   ringbuffer->core_audio->element =
       GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsrc);
   ringbuffer->core_audio->is_src = TRUE;

   /* By default the coreaudio instance created by the ringbuffer
    * has device_id==kAudioDeviceUnknown. The user might have
    * selected a different one here
    */
   if (ringbuffer->core_audio->device_id != osxsrc->device_id)
     ringbuffer->core_audio->device_id = osxsrc->device_id;

   return GST_AUDIO_RING_BUFFER (ringbuffer);
 }

 static OSStatus
 gst_osx_audio_src_io_proc (GstOsxAudioRingBuffer * buf,
     AudioUnitRenderActionFlags * ioActionFlags,
     const AudioTimeStamp * inTimeStamp,
     UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList * bufferList)
 {
   OSStatus status;
   guint8 *writeptr;
   gint writeseg;
   gint len;
   gint remaining;
   UInt32 n;
   gint offset = 0;

   /* Previous invoke of AudioUnitRender changed mDataByteSize into
    * number of bytes actually read. Reset the members. */
   for (n = 0; n < buf->core_audio->recBufferList->mNumberBuffers; ++n) {
     buf->core_audio->recBufferList->mBuffers[n].mDataByteSize =
         buf->core_audio->recBufferSize;
   }

   status = AudioUnitRender (buf->core_audio->audiounit, ioActionFlags,
       inTimeStamp, inBusNumber, inNumberFrames, buf->core_audio->recBufferList);

   if (status) {
     GST_WARNING_OBJECT (buf, "AudioUnitRender returned %d", (int) status);
     return status;
   }

   /* TODO: To support non-interleaved audio, go over all mBuffers,
    *       not just the first one. */

   remaining = buf->core_audio->recBufferList->mBuffers[0].mDataByteSize;

   while (remaining) {
     if (!gst_audio_ring_buffer_prepare_read (GST_AUDIO_RING_BUFFER (buf),
             &writeseg, &writeptr, &len))
       return 0;

     len -= buf->segoffset;

     if (len > remaining)
       len = remaining;

     memcpy (writeptr + buf->segoffset,
         (char *) buf->core_audio->recBufferList->mBuffers[0].mData + offset,
         len);

     buf->segoffset += len;
     offset += len;
     remaining -= len;

     if ((gint) buf->segoffset == GST_AUDIO_RING_BUFFER (buf)->spec.segsize) {
       /* we wrote one segment */
       gst_audio_ring_buffer_advance (GST_AUDIO_RING_BUFFER (buf), 1);

       buf->segoffset = 0;
     }
   }
   return 0;
 }

 static void
 gst_osx_audio_src_osxelement_init (gpointer g_iface, gpointer iface_data)
 {
   GstOsxAudioElementInterface *iface = (GstOsxAudioElementInterface *) g_iface;

   iface->io_proc = (AURenderCallback) gst_osx_audio_src_io_proc;
 }
	/*
	* GStreamer
	* Copyright (C) 2005,2006 Zaheer Abbas Merali <zaheerabbas at merali dot org>
	* Copyright (C) 2008 Pioneers of the Inevitable <songbird@songbirdnest.com>
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
	* DEALINGS IN THE SOFTWARE.
	*
	* Alternatively, the contents of this file may be used under the
	* GNU Lesser General Public License Version 2.1 (the "LGPL"), in
	* which case the following provisions apply instead of the ones
	* mentioned above:
	*
	* 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.
	*/

	/**
	* SECTION:element-osxaudiosrc
	*
	* This element captures raw audio samples using the CoreAudio api.
	*
	* <refsect2>
	* <title>Example launch line</title>
	* \|[
	* gst-launch-1.0 osxaudiosrc ! wavenc ! filesink location=audio.wav
	* ]\|
	* </refsect2>
	*/

	#ifdef HAVE_CONFIG_H
	# include <config.h>
	#endif

	#include <gst/gst.h>
	#include "gstosxaudiosrc.h"
	#include "gstosxaudioelement.h"

	GST_DEBUG_CATEGORY_STATIC (osx_audiosrc_debug);
	#define GST_CAT_DEFAULT osx_audiosrc_debug

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

	enum
	{
	ARG_0,
	ARG_DEVICE
	};

	static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
	GST_PAD_SRC,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS (GST_OSX_AUDIO_SRC_CAPS)
	);

	static void gst_osx_audio_src_set_property (GObject * object, guint prop_id,
	const GValue * value, GParamSpec * pspec);
	static void gst_osx_audio_src_get_property (GObject * object, guint prop_id,
	GValue * value, GParamSpec * pspec);

	static GstStateChangeReturn
	gst_osx_audio_src_change_state (GstElement * element,
	GstStateChange transition);

	static GstCaps gst_osx_audio_src_get_caps (GstBaseSrc src, GstCaps * filter);

	static GstAudioRingBuffer *gst_osx_audio_src_create_ringbuffer (GstAudioBaseSrc
	* src);
	static void gst_osx_audio_src_osxelement_init (gpointer g_iface,
	gpointer iface_data);
	static OSStatus gst_osx_audio_src_io_proc (GstOsxAudioRingBuffer * buf,
	AudioUnitRenderActionFlags * ioActionFlags,
	const AudioTimeStamp * inTimeStamp, UInt32 inBusNumber,
	UInt32 inNumberFrames, AudioBufferList * bufferList);

	static void
	gst_osx_audio_src_do_init (GType type)
	{
	static const GInterfaceInfo osxelement_info = {
	gst_osx_audio_src_osxelement_init,
	NULL,
	NULL
	};

	GST_DEBUG_CATEGORY_INIT (osx_audiosrc_debug, "osxaudiosrc", 0,
	"OSX Audio Src");
	g_type_add_interface_static (type, GST_OSX_AUDIO_ELEMENT_TYPE,
	&osxelement_info);
	}

	#define gst_osx_audio_src_parent_class parent_class
	G_DEFINE_TYPE_WITH_CODE (GstOsxAudioSrc, gst_osx_audio_src,
	GST_TYPE_AUDIO_BASE_SRC, gst_osx_audio_src_do_init (g_define_type_id));

	static void
	gst_osx_audio_src_class_init (GstOsxAudioSrcClass * klass)
	{
	GObjectClass *gobject_class;
	GstElementClass *gstelement_class;
	GstBaseSrcClass *gstbasesrc_class;
	GstAudioBaseSrcClass *gstaudiobasesrc_class;

	gobject_class = (GObjectClass *) klass;
	gstelement_class = (GstElementClass *) klass;
	gstbasesrc_class = (GstBaseSrcClass *) klass;
	gstaudiobasesrc_class = (GstAudioBaseSrcClass *) klass;

	gobject_class->set_property = gst_osx_audio_src_set_property;
	gobject_class->get_property = gst_osx_audio_src_get_property;

	gstelement_class->change_state =
	GST_DEBUG_FUNCPTR (gst_osx_audio_src_change_state);

	gstbasesrc_class->get_caps = GST_DEBUG_FUNCPTR (gst_osx_audio_src_get_caps);

	g_object_class_install_property (gobject_class, ARG_DEVICE,
	g_param_spec_int ("device", "Device ID", "Device ID of input device",
	0, G_MAXINT, 0, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	gstaudiobasesrc_class->create_ringbuffer =
	GST_DEBUG_FUNCPTR (gst_osx_audio_src_create_ringbuffer);

	gst_element_class_add_static_pad_template (gstelement_class, &src_factory);

	gst_element_class_set_static_metadata (gstelement_class, "Audio Source (OSX)",
	"Source/Audio",
	"Input from a sound card in OS X",
	"Zaheer Abbas Merali <zaheerabbas at merali dot org>");
	}

	static void
	gst_osx_audio_src_init (GstOsxAudioSrc * src)
	{
	gst_base_src_set_live (GST_BASE_SRC (src), TRUE);

	src->device_id = kAudioDeviceUnknown;
	}

	static void
	gst_osx_audio_src_set_property (GObject * object, guint prop_id,
	const GValue * value, GParamSpec * pspec)
	{
	GstOsxAudioSrc *src = GST_OSX_AUDIO_SRC (object);

	switch (prop_id) {
	case ARG_DEVICE:
	src->device_id = g_value_get_int (value);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static void
	gst_osx_audio_src_get_property (GObject * object, guint prop_id,
	GValue * value, GParamSpec * pspec)
	{
	GstOsxAudioSrc *src = GST_OSX_AUDIO_SRC (object);

	switch (prop_id) {
	case ARG_DEVICE:
	g_value_set_int (value, src->device_id);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static GstStateChangeReturn
	gst_osx_audio_src_change_state (GstElement * element, GstStateChange transition)
	{
	GstOsxAudioSrc *osxsrc = GST_OSX_AUDIO_SRC (element);
	GstOsxAudioRingBuffer *ringbuffer;
	GstStateChangeReturn ret;

	switch (transition) {
	default:
	break;
	}

	ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
	if (ret == GST_STATE_CHANGE_FAILURE)
	goto out;

	switch (transition) {
	case GST_STATE_CHANGE_NULL_TO_READY:
	/* The device is open now, so fix our device_id if it changed */
	ringbuffer =
	GST_OSX_AUDIO_RING_BUFFER (GST_AUDIO_BASE_SRC (osxsrc)->ringbuffer);
	if (ringbuffer->core_audio->device_id != osxsrc->device_id) {
	osxsrc->device_id = ringbuffer->core_audio->device_id;
	g_object_notify (G_OBJECT (osxsrc), "device");
	}
	break;

	default:
	break;
	}

	out:
	return ret;
	}

	static GstCaps *
	gst_osx_audio_src_get_caps (GstBaseSrc * src, GstCaps * filter)
	{
	GstOsxAudioSrc *osxsrc;
	GstAudioRingBuffer *buf;
	GstOsxAudioRingBuffer *osxbuf;
	GstCaps caps, filtered_caps;

	osxsrc = GST_OSX_AUDIO_SRC (src);

	GST_OBJECT_LOCK (osxsrc);
	buf = GST_AUDIO_BASE_SRC (src)->ringbuffer;
	if (buf)
	gst_object_ref (buf);
	GST_OBJECT_UNLOCK (osxsrc);

	if (!buf) {
	GST_DEBUG_OBJECT (src, "no ring buffer, using template caps");
	return GST_BASE_SRC_CLASS (parent_class)->get_caps (src, filter);
	}

	osxbuf = GST_OSX_AUDIO_RING_BUFFER (buf);

	/* protect against cached_caps going away */
	GST_OBJECT_LOCK (buf);

	if (osxbuf->core_audio->cached_caps_valid) {
	GST_LOG_OBJECT (src, "Returning cached caps");
	caps = gst_caps_ref (osxbuf->core_audio->cached_caps);
	} else if (buf->open) {
	GstCaps *template_caps;

	/* Get template caps */
	template_caps =
	gst_pad_get_pad_template_caps (GST_AUDIO_BASE_SRC_PAD (osxsrc));

	/* Device is open, let's probe its caps */
	caps = gst_core_audio_probe_caps (osxbuf->core_audio, template_caps);
	gst_caps_replace (&osxbuf->core_audio->cached_caps, caps);

	gst_caps_unref (template_caps);
	} else {
	GST_DEBUG_OBJECT (src, "ring buffer not open, using template caps");
	caps = GST_BASE_SRC_CLASS (parent_class)->get_caps (src, NULL);
	}

	GST_OBJECT_UNLOCK (buf);

	gst_object_unref (buf);

	if (!caps)
	return NULL;

	if (!filter)
	return caps;

	/* Take care of filtered caps */
	filtered_caps =
	gst_caps_intersect_full (filter, caps, GST_CAPS_INTERSECT_FIRST);
	gst_caps_unref (caps);
	return filtered_caps;
	}

	static GstAudioRingBuffer *
	gst_osx_audio_src_create_ringbuffer (GstAudioBaseSrc * src)
	{
	GstOsxAudioSrc *osxsrc;
	GstOsxAudioRingBuffer *ringbuffer;

	osxsrc = GST_OSX_AUDIO_SRC (src);

	GST_DEBUG_OBJECT (osxsrc, "Creating ringbuffer");
	ringbuffer = g_object_new (GST_TYPE_OSX_AUDIO_RING_BUFFER, NULL);
	GST_DEBUG_OBJECT (osxsrc, "osx src 0x%p element 0x%p ioproc 0x%p", osxsrc,
	GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsrc),
	(void *) gst_osx_audio_src_io_proc);

	ringbuffer->core_audio->element =
	GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsrc);
	ringbuffer->core_audio->is_src = TRUE;

	/* By default the coreaudio instance created by the ringbuffer
	* has device_id==kAudioDeviceUnknown. The user might have
	* selected a different one here
	*/
	if (ringbuffer->core_audio->device_id != osxsrc->device_id)
	ringbuffer->core_audio->device_id = osxsrc->device_id;

	return GST_AUDIO_RING_BUFFER (ringbuffer);
	}

	static OSStatus
	gst_osx_audio_src_io_proc (GstOsxAudioRingBuffer * buf,
	AudioUnitRenderActionFlags * ioActionFlags,
	const AudioTimeStamp * inTimeStamp,
	UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList * bufferList)
	{
	OSStatus status;
	guint8 *writeptr;
	gint writeseg;
	gint len;
	gint remaining;
	UInt32 n;
	gint offset = 0;

	/* Previous invoke of AudioUnitRender changed mDataByteSize into
	* number of bytes actually read. Reset the members. */
	for (n = 0; n < buf->core_audio->recBufferList->mNumberBuffers; ++n) {
	buf->core_audio->recBufferList->mBuffers[n].mDataByteSize =
	buf->core_audio->recBufferSize;
	}

	status = AudioUnitRender (buf->core_audio->audiounit, ioActionFlags,
	inTimeStamp, inBusNumber, inNumberFrames, buf->core_audio->recBufferList);

	if (status) {
	GST_WARNING_OBJECT (buf, "AudioUnitRender returned %d", (int) status);
	return status;
	}

	/* TODO: To support non-interleaved audio, go over all mBuffers,
	* not just the first one. */

	remaining = buf->core_audio->recBufferList->mBuffers[0].mDataByteSize;

	while (remaining) {
	if (!gst_audio_ring_buffer_prepare_read (GST_AUDIO_RING_BUFFER (buf),
	&writeseg, &writeptr, &len))
	return 0;

	len -= buf->segoffset;

	if (len > remaining)
	len = remaining;

	memcpy (writeptr + buf->segoffset,
	(char *) buf->core_audio->recBufferList->mBuffers[0].mData + offset,
	len);

	buf->segoffset += len;
	offset += len;
	remaining -= len;

	if ((gint) buf->segoffset == GST_AUDIO_RING_BUFFER (buf)->spec.segsize) {
	/* we wrote one segment */
	gst_audio_ring_buffer_advance (GST_AUDIO_RING_BUFFER (buf), 1);

	buf->segoffset = 0;
	}
	}
	return 0;
	}

	static void
	gst_osx_audio_src_osxelement_init (gpointer g_iface, gpointer iface_data)
	{
	GstOsxAudioElementInterface iface = (GstOsxAudioElementInterface ) g_iface;

	iface->io_proc = (AURenderCallback) gst_osx_audio_src_io_proc;
	}