sys/osxaudio/gstosxaudiosink.c - mtk-gst-plugins-good-debian - Git at Google

 /*
  * GStreamer
  * Copyright (C) 2005,2006 Zaheer Abbas Merali <zaheerabbas at merali dot org>
  * Copyright (C) 2007,2008 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., 59 Temple Place - Suite 330,
  * Boston, MA 02111-1307, USA.
  *
  * The development of this code was made possible due to the involvement of
  * Pioneers of the Inevitable, the creators of the Songbird Music player
  *
  */

 /**
  * SECTION:element-osxaudiosink
  *
  * This element renders raw audio samples using the CoreAudio api.
  *
  * <refsect2>
  * <title>Example pipelines</title>
  * |[
  * gst-launch filesrc location=sine.ogg ! oggdemux ! vorbisdec ! audioconvert ! audioresample ! osxaudiosink
  * ]| Play an Ogg/Vorbis file.
  * </refsect2>
  *
  * Last reviewed on 2006-03-01 (0.10.4)
  */

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

 #include <gst/gst.h>
 #include <CoreAudio/CoreAudio.h>
 #include <CoreAudio/AudioHardware.h>
 #include "gstosxaudiosink.h"
 #include "gstosxaudioelement.h"

 GST_DEBUG_CATEGORY_STATIC (osx_audiosink_debug);
 #define GST_CAT_DEFAULT osx_audiosink_debug

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

 enum
 {
   ARG_0,
   ARG_DEVICE,
   ARG_VOLUME
 };

 #define DEFAULT_VOLUME 1.0

 static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_SINK,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("audio/x-raw-float, "
         "endianness = (int) {" G_STRINGIFY (G_BYTE_ORDER) " }, "
         "signed = (boolean) { TRUE }, "
         "width = (int) 32, "
         "depth = (int) 32, "
         "rate = (int) [1, MAX], " "channels = (int) [1, MAX]")
     );

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

 static GstRingBuffer *gst_osx_audio_sink_create_ringbuffer (GstBaseAudioSink *
     sink);
 static void gst_osx_audio_sink_osxelement_init (gpointer g_iface,
     gpointer iface_data);
 static void gst_osx_audio_sink_select_device (GstOsxAudioSink * osxsink);
 static void gst_osx_audio_sink_set_volume (GstOsxAudioSink * sink);

 static OSStatus gst_osx_audio_sink_io_proc (GstOsxRingBuffer * buf,
     AudioUnitRenderActionFlags * ioActionFlags,
     const AudioTimeStamp * inTimeStamp,
     UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList * bufferList);

 static void
 gst_osx_audio_sink_do_init (GType type)
 {
   static const GInterfaceInfo osxelement_info = {
     gst_osx_audio_sink_osxelement_init,
     NULL,
     NULL
   };

   GST_DEBUG_CATEGORY_INIT (osx_audiosink_debug, "osxaudiosink", 0,
       "OSX Audio Sink");
   GST_DEBUG ("Adding static interface");
   g_type_add_interface_static (type, GST_OSX_AUDIO_ELEMENT_TYPE,
       &osxelement_info);
 }

 GST_BOILERPLATE_FULL (GstOsxAudioSink, gst_osx_audio_sink, GstBaseAudioSink,
     GST_TYPE_BASE_AUDIO_SINK, gst_osx_audio_sink_do_init);

 static void
 gst_osx_audio_sink_base_init (gpointer g_class)
 {
   GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

   gst_element_class_add_pad_template (element_class,
       gst_static_pad_template_get (&sink_factory));

   gst_element_class_set_static_metadata (element_class, "Audio Sink (OSX)",
       "Sink/Audio",
       "Output to a sound card in OS X",
       "Zaheer Abbas Merali <zaheerabbas at merali dot org>");
 }

 static void
 gst_osx_audio_sink_class_init (GstOsxAudioSinkClass * klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *gstelement_class;
   GstBaseSinkClass *gstbasesink_class;
   GstBaseAudioSinkClass *gstbaseaudiosink_class;

   gobject_class = (GObjectClass *) klass;
   gstelement_class = (GstElementClass *) klass;
   gstbasesink_class = (GstBaseSinkClass *) klass;
   gstbaseaudiosink_class = (GstBaseAudioSinkClass *) klass;

   parent_class = g_type_class_peek_parent (klass);

   gobject_class->set_property = gst_osx_audio_sink_set_property;
   gobject_class->get_property = gst_osx_audio_sink_get_property;

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

   g_object_class_install_property (gobject_class, ARG_VOLUME,
       g_param_spec_double ("volume", "Volume", "Volume of this stream",
           0, 1.0, 1.0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   gstbaseaudiosink_class->create_ringbuffer =
       GST_DEBUG_FUNCPTR (gst_osx_audio_sink_create_ringbuffer);
 }

 static void
 gst_osx_audio_sink_init (GstOsxAudioSink * sink, GstOsxAudioSinkClass * gclass)
 {
   GST_DEBUG ("Initialising object");

   sink->device_id = kAudioDeviceUnknown;
   sink->volume = DEFAULT_VOLUME;
 }

 static void
 gst_osx_audio_sink_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec)
 {
   GstOsxAudioSink *sink = GST_OSX_AUDIO_SINK (object);

   switch (prop_id) {
     case ARG_DEVICE:
       sink->device_id = g_value_get_int (value);
       break;
     case ARG_VOLUME:
       sink->volume = g_value_get_double (value);
       gst_osx_audio_sink_set_volume (sink);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static void
 gst_osx_audio_sink_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec)
 {
   GstOsxAudioSink *sink = GST_OSX_AUDIO_SINK (object);
   switch (prop_id) {
     case ARG_DEVICE:
       g_value_set_int (value, sink->device_id);
       break;
     case ARG_VOLUME:
       g_value_set_double (value, sink->volume);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static GstRingBuffer *
 gst_osx_audio_sink_create_ringbuffer (GstBaseAudioSink * sink)
 {
   GstOsxAudioSink *osxsink;
   GstOsxRingBuffer *ringbuffer;

   osxsink = GST_OSX_AUDIO_SINK (sink);

   gst_osx_audio_sink_select_device (osxsink);

   GST_DEBUG ("Creating ringbuffer");
   ringbuffer = g_object_new (GST_TYPE_OSX_RING_BUFFER, NULL);
   GST_DEBUG ("osx sink 0x%p element 0x%p  ioproc 0x%p", osxsink,
       GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsink),
       (void *) gst_osx_audio_sink_io_proc);

   gst_osx_audio_sink_set_volume (osxsink);

   ringbuffer->element = GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsink);
   ringbuffer->device_id = osxsink->device_id;

   return GST_RING_BUFFER (ringbuffer);
 }

 /* HALOutput AudioUnit will request fairly arbitrarily-sized chunks of data,
  * not of a fixed size. So, we keep track of where in the current ringbuffer
  * segment we are, and only advance the segment once we've read the whole
  * thing */
 static OSStatus
 gst_osx_audio_sink_io_proc (GstOsxRingBuffer * buf,
     AudioUnitRenderActionFlags * ioActionFlags,
     const AudioTimeStamp * inTimeStamp,
     UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList * bufferList)
 {
   guint8 *readptr;
   gint readseg;
   gint len;
   gint remaining = bufferList->mBuffers[0].mDataByteSize;
   gint offset = 0;

   while (remaining) {
     if (!gst_ring_buffer_prepare_read (GST_RING_BUFFER (buf),
             &readseg, &readptr, &len))
       return 0;

     len -= buf->segoffset;

     if (len > remaining)
       len = remaining;

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

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

     if ((gint) buf->segoffset == GST_RING_BUFFER (buf)->spec.segsize) {
       /* clear written samples */
       gst_ring_buffer_clear (GST_RING_BUFFER (buf), readseg);

       /* we wrote one segment */
       gst_ring_buffer_advance (GST_RING_BUFFER (buf), 1);

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

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

   iface->io_proc = (AURenderCallback) gst_osx_audio_sink_io_proc;
 }

 static void
 gst_osx_audio_sink_set_volume (GstOsxAudioSink * sink)
 {
   if (!sink->audiounit)
     return;

   AudioUnitSetParameter (sink->audiounit, kHALOutputParam_Volume,
       kAudioUnitScope_Global, 0, (float) sink->volume, 0);
 }

 static void
 gst_osx_audio_sink_select_device (GstOsxAudioSink * osxsink)
 {
   OSStatus status;
   UInt32 propertySize;

   if (osxsink->device_id == kAudioDeviceUnknown) {
     /* If no specific device has been selected by the user, then pick the
      * default device */
     GST_DEBUG_OBJECT (osxsink, "Selecting device for OSXAudioSink");
     propertySize = sizeof (osxsink->device_id);
     status =
         AudioHardwareGetProperty (kAudioHardwarePropertyDefaultOutputDevice,
         &propertySize, &osxsink->device_id);

     if (status) {
       GST_WARNING_OBJECT (osxsink,
           "AudioHardwareGetProperty returned %d", (int) status);
     } else {
       GST_DEBUG_OBJECT (osxsink, "AudioHardwareGetProperty returned 0");
     }

     if (osxsink->device_id == kAudioDeviceUnknown) {
       GST_WARNING_OBJECT (osxsink,
           "AudioHardwareGetProperty: device_id is kAudioDeviceUnknown");
     }

     GST_DEBUG_OBJECT (osxsink, "AudioHardwareGetProperty: device_id is %lu",
         (long) osxsink->device_id);
   }
 }
	/*
	* GStreamer
	* Copyright (C) 2005,2006 Zaheer Abbas Merali <zaheerabbas at merali dot org>
	* Copyright (C) 2007,2008 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., 59 Temple Place - Suite 330,
	* Boston, MA 02111-1307, USA.
	*
	* The development of this code was made possible due to the involvement of
	* Pioneers of the Inevitable, the creators of the Songbird Music player
	*
	*/

	/**
	* SECTION:element-osxaudiosink
	*
	* This element renders raw audio samples using the CoreAudio api.
	*
	* <refsect2>
	* <title>Example pipelines</title>
	* \|[
	* gst-launch filesrc location=sine.ogg ! oggdemux ! vorbisdec ! audioconvert ! audioresample ! osxaudiosink
	* ]\| Play an Ogg/Vorbis file.
	* </refsect2>
	*
	* Last reviewed on 2006-03-01 (0.10.4)
	*/

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

	#include <gst/gst.h>
	#include <CoreAudio/CoreAudio.h>
	#include <CoreAudio/AudioHardware.h>
	#include "gstosxaudiosink.h"
	#include "gstosxaudioelement.h"

	GST_DEBUG_CATEGORY_STATIC (osx_audiosink_debug);
	#define GST_CAT_DEFAULT osx_audiosink_debug

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

	enum
	{
	ARG_0,
	ARG_DEVICE,
	ARG_VOLUME
	};

	#define DEFAULT_VOLUME 1.0

	static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
	GST_PAD_SINK,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("audio/x-raw-float, "
	"endianness = (int) {" G_STRINGIFY (G_BYTE_ORDER) " }, "
	"signed = (boolean) { TRUE }, "
	"width = (int) 32, "
	"depth = (int) 32, "
	"rate = (int) [1, MAX], " "channels = (int) [1, MAX]")
	);

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

	static GstRingBuffer gst_osx_audio_sink_create_ringbuffer (GstBaseAudioSink
	sink);
	static void gst_osx_audio_sink_osxelement_init (gpointer g_iface,
	gpointer iface_data);
	static void gst_osx_audio_sink_select_device (GstOsxAudioSink * osxsink);
	static void gst_osx_audio_sink_set_volume (GstOsxAudioSink * sink);

	static OSStatus gst_osx_audio_sink_io_proc (GstOsxRingBuffer * buf,
	AudioUnitRenderActionFlags * ioActionFlags,
	const AudioTimeStamp * inTimeStamp,
	UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList * bufferList);

	static void
	gst_osx_audio_sink_do_init (GType type)
	{
	static const GInterfaceInfo osxelement_info = {
	gst_osx_audio_sink_osxelement_init,
	NULL,
	NULL
	};

	GST_DEBUG_CATEGORY_INIT (osx_audiosink_debug, "osxaudiosink", 0,
	"OSX Audio Sink");
	GST_DEBUG ("Adding static interface");
	g_type_add_interface_static (type, GST_OSX_AUDIO_ELEMENT_TYPE,
	&osxelement_info);
	}

	GST_BOILERPLATE_FULL (GstOsxAudioSink, gst_osx_audio_sink, GstBaseAudioSink,
	GST_TYPE_BASE_AUDIO_SINK, gst_osx_audio_sink_do_init);

	static void
	gst_osx_audio_sink_base_init (gpointer g_class)
	{
	GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

	gst_element_class_add_pad_template (element_class,
	gst_static_pad_template_get (&sink_factory));

	gst_element_class_set_static_metadata (element_class, "Audio Sink (OSX)",
	"Sink/Audio",
	"Output to a sound card in OS X",
	"Zaheer Abbas Merali <zaheerabbas at merali dot org>");
	}

	static void
	gst_osx_audio_sink_class_init (GstOsxAudioSinkClass * klass)
	{
	GObjectClass *gobject_class;
	GstElementClass *gstelement_class;
	GstBaseSinkClass *gstbasesink_class;
	GstBaseAudioSinkClass *gstbaseaudiosink_class;

	gobject_class = (GObjectClass *) klass;
	gstelement_class = (GstElementClass *) klass;
	gstbasesink_class = (GstBaseSinkClass *) klass;
	gstbaseaudiosink_class = (GstBaseAudioSinkClass *) klass;

	parent_class = g_type_class_peek_parent (klass);

	gobject_class->set_property = gst_osx_audio_sink_set_property;
	gobject_class->get_property = gst_osx_audio_sink_get_property;

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

	g_object_class_install_property (gobject_class, ARG_VOLUME,
	g_param_spec_double ("volume", "Volume", "Volume of this stream",
	0, 1.0, 1.0, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	gstbaseaudiosink_class->create_ringbuffer =
	GST_DEBUG_FUNCPTR (gst_osx_audio_sink_create_ringbuffer);
	}

	static void
	gst_osx_audio_sink_init (GstOsxAudioSink * sink, GstOsxAudioSinkClass * gclass)
	{
	GST_DEBUG ("Initialising object");

	sink->device_id = kAudioDeviceUnknown;
	sink->volume = DEFAULT_VOLUME;
	}

	static void
	gst_osx_audio_sink_set_property (GObject * object, guint prop_id,
	const GValue * value, GParamSpec * pspec)
	{
	GstOsxAudioSink *sink = GST_OSX_AUDIO_SINK (object);

	switch (prop_id) {
	case ARG_DEVICE:
	sink->device_id = g_value_get_int (value);
	break;
	case ARG_VOLUME:
	sink->volume = g_value_get_double (value);
	gst_osx_audio_sink_set_volume (sink);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static void
	gst_osx_audio_sink_get_property (GObject * object, guint prop_id,
	GValue * value, GParamSpec * pspec)
	{
	GstOsxAudioSink *sink = GST_OSX_AUDIO_SINK (object);
	switch (prop_id) {
	case ARG_DEVICE:
	g_value_set_int (value, sink->device_id);
	break;
	case ARG_VOLUME:
	g_value_set_double (value, sink->volume);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static GstRingBuffer *
	gst_osx_audio_sink_create_ringbuffer (GstBaseAudioSink * sink)
	{
	GstOsxAudioSink *osxsink;
	GstOsxRingBuffer *ringbuffer;

	osxsink = GST_OSX_AUDIO_SINK (sink);

	gst_osx_audio_sink_select_device (osxsink);

	GST_DEBUG ("Creating ringbuffer");
	ringbuffer = g_object_new (GST_TYPE_OSX_RING_BUFFER, NULL);
	GST_DEBUG ("osx sink 0x%p element 0x%p ioproc 0x%p", osxsink,
	GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsink),
	(void *) gst_osx_audio_sink_io_proc);

	gst_osx_audio_sink_set_volume (osxsink);

	ringbuffer->element = GST_OSX_AUDIO_ELEMENT_GET_INTERFACE (osxsink);
	ringbuffer->device_id = osxsink->device_id;

	return GST_RING_BUFFER (ringbuffer);
	}

	/* HALOutput AudioUnit will request fairly arbitrarily-sized chunks of data,
	* not of a fixed size. So, we keep track of where in the current ringbuffer
	* segment we are, and only advance the segment once we've read the whole
	* thing */
	static OSStatus
	gst_osx_audio_sink_io_proc (GstOsxRingBuffer * buf,
	AudioUnitRenderActionFlags * ioActionFlags,
	const AudioTimeStamp * inTimeStamp,
	UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList * bufferList)
	{
	guint8 *readptr;
	gint readseg;
	gint len;
	gint remaining = bufferList->mBuffers[0].mDataByteSize;
	gint offset = 0;

	while (remaining) {
	if (!gst_ring_buffer_prepare_read (GST_RING_BUFFER (buf),
	&readseg, &readptr, &len))
	return 0;

	len -= buf->segoffset;

	if (len > remaining)
	len = remaining;

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

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

	if ((gint) buf->segoffset == GST_RING_BUFFER (buf)->spec.segsize) {
	/* clear written samples */
	gst_ring_buffer_clear (GST_RING_BUFFER (buf), readseg);

	/* we wrote one segment */
	gst_ring_buffer_advance (GST_RING_BUFFER (buf), 1);

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

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

	iface->io_proc = (AURenderCallback) gst_osx_audio_sink_io_proc;
	}

	static void
	gst_osx_audio_sink_set_volume (GstOsxAudioSink * sink)
	{
	if (!sink->audiounit)
	return;

	AudioUnitSetParameter (sink->audiounit, kHALOutputParam_Volume,
	kAudioUnitScope_Global, 0, (float) sink->volume, 0);
	}

	static void
	gst_osx_audio_sink_select_device (GstOsxAudioSink * osxsink)
	{
	OSStatus status;
	UInt32 propertySize;

	if (osxsink->device_id == kAudioDeviceUnknown) {
	/* If no specific device has been selected by the user, then pick the
	* default device */
	GST_DEBUG_OBJECT (osxsink, "Selecting device for OSXAudioSink");
	propertySize = sizeof (osxsink->device_id);
	status =
	AudioHardwareGetProperty (kAudioHardwarePropertyDefaultOutputDevice,
	&propertySize, &osxsink->device_id);

	if (status) {
	GST_WARNING_OBJECT (osxsink,
	"AudioHardwareGetProperty returned %d", (int) status);
	} else {
	GST_DEBUG_OBJECT (osxsink, "AudioHardwareGetProperty returned 0");
	}

	if (osxsink->device_id == kAudioDeviceUnknown) {
	GST_WARNING_OBJECT (osxsink,
	"AudioHardwareGetProperty: device_id is kAudioDeviceUnknown");
	}

	GST_DEBUG_OBJECT (osxsink, "AudioHardwareGetProperty: device_id is %lu",
	(long) osxsink->device_id);
	}
	}