Commit cb163be4 authored by Zaheer Abbas Merali's avatar Zaheer Abbas Merali
Browse files

sys/osxaudio/: Port of osxaudiosink to 0.10

Original commit message from CVS:
2006-04-26  Zaheer Abbas Merali  <zaheerabbas at merali dot org>

* sys/osxaudio/Makefile.am:
* sys/osxaudio/gstosxaudioelement.c:
(gst_osx_audio_element_get_type),
(gst_osx_audio_element_class_init):
* sys/osxaudio/gstosxaudioelement.h:
* sys/osxaudio/gstosxaudiosink.c:
(gst_osx_audio_sink_osxelement_do_init),
(gst_osx_audio_sink_base_init), (gst_osx_audio_sink_class_init),
(gst_osx_audio_sink_init), (gst_osx_audio_sink_set_property),
(gst_osx_audio_sink_get_property), (gst_osx_audio_sink_getcaps),
(gst_osx_audio_sink_create_ringbuffer),
(gst_osx_audio_sink_io_proc), (gst_osx_audio_sink_osxelement_init),
(plugin_init):
* sys/osxaudio/gstosxaudiosink.h:
Port of osxaudiosink to 0.10
parent a3fca568
2006-04-26 Zaheer Abbas Merali <zaheerabbas at merali dot org>
* sys/osxaudio/Makefile.am:
* sys/osxaudio/gstosxaudioelement.c:
(gst_osx_audio_element_get_type),
(gst_osx_audio_element_class_init):
* sys/osxaudio/gstosxaudioelement.h:
* sys/osxaudio/gstosxaudiosink.c:
(gst_osx_audio_sink_osxelement_do_init),
(gst_osx_audio_sink_base_init), (gst_osx_audio_sink_class_init),
(gst_osx_audio_sink_init), (gst_osx_audio_sink_set_property),
(gst_osx_audio_sink_get_property), (gst_osx_audio_sink_getcaps),
(gst_osx_audio_sink_create_ringbuffer),
(gst_osx_audio_sink_io_proc), (gst_osx_audio_sink_osxelement_init),
(plugin_init):
* sys/osxaudio/gstosxaudiosink.h:
Port of osxaudiosink to 0.10
2006-04-26 Wim Taymans <wim@fluendo.com>
* ext/esd/esdsink.c: (gst_esdsink_prepare), (gst_esdsink_delay):
......
plugin_LTLIBRARIES = libgstosxaudio.la
libgstosxaudio_la_SOURCES = gstosxaudio.c \
libgstosxaudio_la_SOURCES = gstosxringbuffer.c \
gstosxaudioelement.c \
gstosxaudiosink.c \
gstosxaudiosrc.c
gstosxaudiosink.c
# FIXME: clean up these linker flags
libgstosxaudio_la_CFLAGS = $(GST_CFLAGS)
libgstosxaudio_la_LIBADD = $(top_builddir)/gst-libs/gst/libgstinterfaces-@GST_MAJORMINOR@.la $(GST_LIBS)
LIBS = -Wl,-framework -Wl,CoreAudio
libgstosxaudio_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS) -framework CoreAudio
libgstosxaudio_la_CFLAGS = $(GST_CFLAGS) $(GST_BASE_CFLAGS) $(GSTPB_BASE_FLAGS)
libgstosxaudio_la_LIBADD = $(GST_LIBS) $(GST_BASE_LIBS) $(GSTPB_BASE_LIBS) -lgstaudio-@GST_MAJORMINOR@
libgstosxaudio_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS) -Wl,-framework -Wl,CoreAudio
noinst_HEADERS = gstosxaudiosink.h \
gstosxaudioelement.h \
gstosxaudiosrc.h
gstosxringbuffer.h
/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wim.taymans@chello.be>
/*
* GStreamer
* Copyright 2006 Zaheer Abbas Merali <zaheerabbas at merali dot org>
*
* 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:
*
* gstosxaudioelement.c:
* 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
......@@ -20,430 +41,50 @@
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <CoreAudio/CoreAudio.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <gst/gst.h>
#include "gstosxaudioelement.h"
enum
{
ARG_0,
ARG_DEVICE
};
/* elementfactory information */
static const GstElementDetails gst_osxaudioelement_details =
GST_ELEMENT_DETAILS ("Audio Mixer (OSX)",
"Generic/Audio",
"Mac OS X audio mixer element",
"Zaheer Abbas Merali <zaheerabbas at merali dot org>");
static void gst_osxaudioelement_base_init (GstOsxAudioElementClass * klass);
static void gst_osxaudioelement_class_init (GstOsxAudioElementClass * klass);
static void gst_osxaudioelement_init (GstOsxAudioElement * osxaudio);
static void gst_osxaudioelement_dispose (GObject * object);
static void gst_osxaudioelement_set_property (GObject * object,
guint prop_id, const GValue * value, GParamSpec * pspec);
static void gst_osxaudioelement_get_property (GObject * object,
guint prop_id, GValue * value, GParamSpec * pspec);
static GstStateChangeReturn gst_osxaudioelement_change_state (GstElement *
element);
static GstElementClass *parent_class = NULL;
static void
gst_osx_audio_element_class_init (GstOsxAudioElementInterface * klass);
GType
gst_osxaudioelement_get_type (void)
gst_osx_audio_element_get_type ()
{
static GType osxaudioelement_type = 0;
static GType gst_osxaudioelement_type = 0;
if (!osxaudioelement_type) {
static const GTypeInfo osxaudioelement_info = {
sizeof (GstOsxAudioElementClass),
(GBaseInitFunc) gst_osxaudioelement_base_init,
if (!gst_osxaudioelement_type) {
static const GTypeInfo gst_osxaudioelement_info = {
sizeof (GstOsxAudioElementInterface),
(GBaseInitFunc) gst_osx_audio_element_class_init,
NULL,
NULL,
(GClassInitFunc) gst_osxaudioelement_class_init,
NULL,
NULL,
sizeof (GstOsxAudioElement),
0,
(GInstanceInitFunc) gst_osxaudioelement_init
0,
NULL,
};
osxaudioelement_type = g_type_register_static (GST_TYPE_ELEMENT,
"GstOsxAudioElement", &osxaudioelement_info, 0);
}
return osxaudioelement_type;
}
static void
gst_osxaudioelement_base_init (GstOsxAudioElementClass * klass)
{
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
klass->device_combinations = NULL;
gst_element_class_set_details (element_class, &gst_osxaudioelement_details);
}
static void
gst_osxaudioelement_class_init (GstOsxAudioElementClass * klass)
{
GObjectClass *gobject_class;
GstElementClass *gstelement_class;
gobject_class = (GObjectClass *) klass;
gstelement_class = (GstElementClass *) klass;
parent_class = g_type_class_peek_parent (klass);
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_DEVICE,
g_param_spec_int ("device", "Device index",
"Mac OS X CoreAudio Device Index (0 usually)", 0, G_MAXINT, 0,
G_PARAM_READWRITE));
gobject_class->set_property = gst_osxaudioelement_set_property;
gobject_class->get_property = gst_osxaudioelement_get_property;
gobject_class->dispose = gst_osxaudioelement_dispose;
gstelement_class->change_state = gst_osxaudioelement_change_state;
}
static void
gst_osxaudioelement_init (GstOsxAudioElement * osxaudio)
{
OSStatus status;
UInt32 propertySize;
pthread_mutex_init (&osxaudio->buffer_mutex, NULL);
pthread_mutex_unlock (&osxaudio->buffer_mutex);
propertySize = sizeof (osxaudio->device_id);
status =
AudioHardwareGetProperty (kAudioHardwarePropertyDefaultOutputDevice,
&propertySize, &(osxaudio->device_id));
if (status) {
GST_DEBUG ("AudioHardwareGetProperty returned %d\n", (int) status);
}
if (osxaudio->device_id == kAudioDeviceUnknown) {
GST_DEBUG ("AudioHardwareGetProperty: device_id is kAudioDeviceUnknown\n");
}
/* get requested buffer length */
propertySize = sizeof (osxaudio->buffer_len);
status =
AudioDeviceGetProperty (osxaudio->device_id, 0, false,
kAudioDevicePropertyBufferSize, &propertySize, &osxaudio->buffer_len);
if (status) {
GST_DEBUG
("AudioDeviceGetProperty returned %d when getting kAudioDevicePropertyBufferSize\n",
(int) status);
}
GST_DEBUG ("%5d osxaudio->buffer_len\n", (int) osxaudio->buffer_len);
}
static void
gst_osxaudioelement_dispose (GObject * object)
{
/* GstOsxAudioElement *osxaudio = (GstOsxAudioElement *) object; */
G_OBJECT_CLASS (parent_class)->dispose (object);
}
/* General purpose Ring-buffering routines */
int
write_buffer (GstOsxAudioElement * osxaudio, unsigned char *data, int len)
{
int len2 = 0;
int x;
while (len > 0) {
if (osxaudio->full_buffers == NUM_BUFS) {
GST_DEBUG ("Buffer overrun\n");
break;
}
x = osxaudio->buffer_len - osxaudio->buf_write_pos;
if (x > len)
x = len;
memcpy (osxaudio->buffer[osxaudio->buf_write] + osxaudio->buf_write_pos,
data + len2, x);
/* accessing common variables, locking mutex */
pthread_mutex_lock (&osxaudio->buffer_mutex);
len2 += x;
len -= x;
osxaudio->buffered_bytes += x;
osxaudio->buf_write_pos += x;
if (osxaudio->buf_write_pos >= osxaudio->buffer_len) {
/* block is full, find next! */
osxaudio->buf_write = (osxaudio->buf_write + 1) % NUM_BUFS;
++osxaudio->full_buffers;
osxaudio->buf_write_pos = 0;
}
pthread_mutex_unlock (&osxaudio->buffer_mutex);
}
return len2;
}
int
read_buffer (GstOsxAudioElement * osxaudio, unsigned char *data)
{
int len2 = 0;
int len = osxaudio->buffer_len;
int x;
while (len > 0) {
if (osxaudio->full_buffers == 0) {
GST_DEBUG ("Buffer underrun\n");
break;
}
x = osxaudio->buffer_len - osxaudio->buf_read_pos;
if (x > len)
x = len;
memcpy (data + len2,
osxaudio->buffer[osxaudio->buf_read] + osxaudio->buf_read_pos, x);
len2 += x;
len -= x;
/* accessing common variables, locking mutex */
pthread_mutex_lock (&osxaudio->buffer_mutex);
osxaudio->buffered_bytes -= x;
osxaudio->buf_read_pos += x;
if (osxaudio->buf_read_pos >= osxaudio->buffer_len) {
/* block is empty, find next! */
osxaudio->buf_read = (osxaudio->buf_read + 1) % NUM_BUFS;
--osxaudio->full_buffers;
osxaudio->buf_read_pos = 0;
}
pthread_mutex_unlock (&osxaudio->buffer_mutex);
}
return len2;
}
/* The function that the CoreAudio thread calls when it has data */
OSStatus
inputAudioDeviceIOProc (AudioDeviceID inDevice, const AudioTimeStamp * inNow,
const AudioBufferList * inInputData, const AudioTimeStamp * inInputTime,
AudioBufferList * outOutputData, const AudioTimeStamp * inOutputTime,
void *inClientData)
{
GstOsxAudioElement *osxaudio = GST_OSXAUDIOELEMENT (inClientData);
write_buffer (GST_OSXAUDIOELEMENT (osxaudio),
(char *) inInputData->mBuffers[0].mData, osxaudio->buffer_len);
return 0;
}
/* The function that the CoreAudio thread calls when it wants more data */
OSStatus
outputAudioDeviceIOProc (AudioDeviceID inDevice, const AudioTimeStamp * inNow,
const AudioBufferList * inInputData, const AudioTimeStamp * inInputTime,
AudioBufferList * outOutputData, const AudioTimeStamp * inOutputTime,
void *inClientData)
{
GstOsxAudioElement *osxaudio = GST_OSXAUDIOELEMENT (inClientData);
outOutputData->mBuffers[0].mDataByteSize =
read_buffer (osxaudio, (char *) outOutputData->mBuffers[0].mData);
return 0;
}
static gboolean
gst_osxaudioelement_open_audio (GstOsxAudioElement * osxaudio, gboolean input)
{
int i;
OSErr status;
GST_INFO ("osxaudioelement: attempting to open sound device");
/* Allocate ring-buffer memory */
for (i = 0; i < NUM_BUFS; i++)
osxaudio->buffer[i] = (unsigned char *) malloc (osxaudio->buffer_len);
if (input) {
status =
AudioDeviceAddIOProc (osxaudio->device_id, inputAudioDeviceIOProc,
osxaudio);
} else {
/* Set the IO proc that CoreAudio will call when it needs data */
status =
AudioDeviceAddIOProc (osxaudio->device_id, outputAudioDeviceIOProc,
osxaudio);
}
if (status) {
GST_DEBUG ("AudioDeviceAddIOProc returned %d\n", (int) status);
return FALSE;
}
pthread_mutex_lock (&osxaudio->buffer_mutex);
/* reset ring-buffer state */
osxaudio->buf_read = 0;
osxaudio->buf_write = 0;
osxaudio->buf_read_pos = 0;
osxaudio->buf_write_pos = 0;
osxaudio->full_buffers = 0;
osxaudio->buffered_bytes = 0;
/* zero buffer */
for (i = 0; i < NUM_BUFS; i++)
bzero (osxaudio->buffer[i], osxaudio->buffer_len);
pthread_mutex_unlock (&osxaudio->buffer_mutex);
return TRUE;
}
static void
gst_osxaudioelement_close_audio (GstOsxAudioElement * osxaudio, gboolean input)
{
OSErr status;
int i;
/* stop callback */
if (input) {
status = AudioDeviceStop (osxaudio->device_id, inputAudioDeviceIOProc);
} else {
status = AudioDeviceStop (osxaudio->device_id, outputAudioDeviceIOProc);
}
if (status)
GST_DEBUG ("AudioDeviceStop returned %d\n", (int) status);
if (input) {
status =
AudioDeviceRemoveIOProc (osxaudio->device_id, inputAudioDeviceIOProc);
} else {
status =
AudioDeviceRemoveIOProc (osxaudio->device_id, outputAudioDeviceIOProc);
gst_osxaudioelement_type = g_type_register_static (G_TYPE_INTERFACE,
"GstOsxAudioElement", &gst_osxaudioelement_info, 0);
/*g_type_interface_add_prerequisite (gst_osxaudioelement_type,
GST_TYPE_IMPLEMENTS_INTERFACE); */
}
if (status)
GST_DEBUG ("AudioDeviceRemoveIOProc " "returned %d\n", (int) status);
for (i = 0; i < NUM_BUFS; i++)
free (osxaudio->buffer[i]);
return gst_osxaudioelement_type;
}
static void
gst_osxaudioelement_set_property (GObject * object,
guint prop_id, const GValue * value, GParamSpec * pspec)
gst_osx_audio_element_class_init (GstOsxAudioElementInterface * klass)
{
GstOsxAudioElement *osxaudio = GST_OSXAUDIOELEMENT (object);
OSStatus status;
int nDevices;
UInt32 propertySize;
int deviceid;
AudioDeviceID *devids;
static gboolean initialized = FALSE;
switch (prop_id) {
case ARG_DEVICE:
/* check index given is in bounds, if not use default device */
status = AudioHardwareGetPropertyInfo (kAudioHardwarePropertyDevices,
&propertySize, NULL);
nDevices = propertySize / sizeof (AudioDeviceID);
deviceid = g_value_get_int (value);
if (deviceid < nDevices) {
devids = malloc (propertySize);
status =
AudioHardwareGetProperty (kAudioHardwarePropertyDevices,
&propertySize, devids);
osxaudio->device_id = devids[deviceid];
free (devids);
} else {
GST_DEBUG ("device index %d out of range. Max index is currently %d\n",
deviceid, nDevices);
}
break;
default:
break;
}
}
if (!initialized) {
static void
gst_osxaudioelement_get_property (GObject * object,
guint prop_id, GValue * value, GParamSpec * pspec)
{
GstOsxAudioElement *osxaudio = GST_OSXAUDIOELEMENT (object);
OSStatus status;
int nDevices;
UInt32 propertySize;
AudioDeviceID *devids;
int i;
switch (prop_id) {
case ARG_DEVICE:
/* figure out what index the current one is */
status = AudioHardwareGetPropertyInfo (kAudioHardwarePropertyDevices,
&propertySize, NULL);
nDevices = propertySize / sizeof (AudioDeviceID);
devids = malloc (propertySize);
status =
AudioHardwareGetProperty (kAudioHardwarePropertyDevices,
&propertySize, devids);
for (i = 0; i < nDevices; i++) {
if (osxaudio->device_id == devids[i])
break;
}
g_value_set_int (value, i);
free (devids);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static GstStateChangeReturn
gst_osxaudioelement_change_state (GstElement * element,
GstStateChange transition)
{
GstOsxAudioElement *osxaudio = GST_OSXAUDIOELEMENT (element);
const GList *padlist;
gboolean input = TRUE;
padlist = gst_element_get_pad_list (element);
if (padlist != NULL) {
GstPad *firstpad = padlist->data;
if (GST_PAD_IS_SINK (firstpad)) {
input = FALSE;
}
}
switch (transition) {
case GST_STATE_CHANGE_NULL_TO_READY:
if (!gst_osxaudioelement_open_audio (osxaudio, input)) {
return GST_STATE_CHANGE_FAILURE;
}
GST_INFO ("osxaudioelement: opened sound device");
break;
case GST_STATE_CHANGE_READY_TO_NULL:
gst_osxaudioelement_close_audio (osxaudio, input);
GST_INFO ("osxaudioelement: closed sound device");
break;
default:
break;
initialized = TRUE;
}
if (GST_ELEMENT_CLASS (parent_class)->change_state)
return GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
/* default virtual functions */
klass->io_proc = NULL;
return GST_STATE_CHANGE_SUCCESS;
}
/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wim.taymans@chello.be>
/*
* GStreamer
* Copyright 2006 Zaheer Abbas Merali <zaheerabbas at merali dot org>
*
* 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:
*
* gstosxaudioelement.h:
* 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
......@@ -20,72 +41,27 @@
* Boston, MA 02111-1307, USA.
*/
#ifndef __GST_OSXAUDIO_ELEMENT_H__
#define __GST_OSXAUDIO_ELEMENT_H__
#ifndef __GST_OSX_AUDIO_ELEMENT_H__
#define __GST_OSX_AUDIO_ELEMENT_H__
#include <gst/gst.h>
#include <CoreAudio/CoreAudio.h>
#include <pthread.h>
/* debugging category */
GST_DEBUG_CATEGORY_EXTERN (osxaudio_debug);
#define GST_CAT_DEFAULT osxaudio_debug
G_BEGIN_DECLS
OSStatus outputAudioDeviceIOProc(AudioDeviceID inDevice, const AudioTimeStamp *inNow, const AudioBufferList *inInputData, const AudioTimeStamp *inInputTime, AudioBufferList *outOutputData, const AudioTimeStamp *inOutputTime, void *inClientData);
OSStatus inputAudioDeviceIOProc(AudioDeviceID inDevice, const AudioTimeStamp *inNow, const AudioBufferList *inInputData, const AudioTimeStamp *inInputTime, AudioBufferList *outOutputData, const AudioTimeStamp *inOutputTime, void *inClientData);
#define GST_TYPE_OSXAUDIOELEMENT \
(gst_osxaudioelement_get_type())
#define GST_OSXAUDIOELEMENT(obj) \
(G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_OSXAUDIOELEMENT,GstOsxAudioElement))
#define GST_OSXAUDIOELEMENT_CLASS(klass) \
(G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_OSXAUDIOELEMENT,GstOsxAudioElementClass))
#define GST_IS_OSXAUDIOELEMENT(obj) \
(G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_OSXAUDIOELEMENT))
#define GST_IS_OSXAUDIOELEMENT_CLASS(klass) \
(G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_OSXAUDIOELEMENT))
#define GST_OSXAUDIOELEMENT_GET_CLASS(obj) \
(G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TYPE_OSXAUDIOELEMENT, GstOsxAudioElementClass))
#define GST_OSX_AUDIO_ELEMENT_TYPE (gst_osx_audio_element_get_type())
#define GST_OSX_AUDIO_ELEMENT(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_OSX_AUDIO_ELEMENT_TYPE, GstOsxAudioElementInterface))
#define GST_IS_OSX_AUDIO_ELEMENT(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_OSX_AUDIO_ELEMENT_TYPE))
#define GST_OSX_AUDIO_ELEMENT_GET_INTERFACE(inst) (G_TYPE_INSTANCE_GET_INTERFACE ((inst), GST_OSX_AUDIO_ELEMENT_TYPE, GstOsxAudioElementInterface))
typedef struct _GstOsxAudioElement GstOsxAudioElement;
typedef struct _GstOsxAudioElementClass GstOsxAudioElementClass;
/* This is large, but best (maybe it should be even larger).
* CoreAudio supposedly has an internal latency in the order of 2ms */
#define NUM_BUFS 128
struct _GstOsxAudioElement