* AUHAL module. This module is a auhal output renderer for VLC OSX. It uses an...

* AUHAL module. This module is a auhal output renderer for VLC OSX. It uses an auhal unit to do analog audio processing. This will allow us to dump the coreaudio resampler later on and will also do automatic channel reordering etc. The module currently does NOT work. The rendering callback is not functioning. I do not know how to solve the issue. I'm adding it, because it's the way to go, and I want others to be able to take a look at it and fix it. 

modules/audio_output/Modules.am

@@ -9,3 +9,4 @@ SOURCES_aout_sdl = sdl.c
 SOURCES_waveout = waveout.c
 SOURCES_hd1000a = hd1000a.cpp
 SOURCES_portaudio = portaudio.c
+SOURCES_auhal = auhal.c

modules/audio_output/auhal.c

+/*****************************************************************************
+ * auhal.c: AUHAL output plugin
+ *****************************************************************************
+ * Copyright (C) 2005 VideoLAN
+ * $Id: coreaudio.c 10101 2005-03-02 16:47:31Z robux4 $
+ *
+ * Authors: Derk-Jan Hartman <hartman at videolan dot org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#include <string.h>
+#include <stdlib.h>
+
+#include <vlc/vlc.h>
+#include <vlc/aout.h>
+
+#include "aout_internal.h"
+
+#include <CoreAudio/CoreAudio.h>
+#include <CoreAudio/CoreAudioTypes.h>
+#include <AudioUnit/AudioUnitProperties.h>
+#include <AudioUnit/AudioUnitParameters.h>
+#include <AudioUnit/AudioOutputUnit.h>
+#include <AudioToolbox/AudioFormat.h>
+
+#define STREAM_FORMAT_MSG( pre, sfm ) \
+    pre ":\nsamplerate: [%ld]\nFormatID: [%4.4s]\nFormatFlags: [%ld]\nBypesPerPacket: [%ld]\nFramesPerPacket: [%ld]\nBytesPerFrame: [%ld]\nChannelsPerFrame: [%ld]\nBitsPerChannel[%ld]", \
+    (UInt32)sfm.mSampleRate, (char *)&sfm.mFormatID, \
+    sfm.mFormatFlags, sfm.mBytesPerPacket, \
+    sfm.mFramesPerPacket, sfm.mBytesPerFrame, \
+    sfm.mChannelsPerFrame, sfm.mBitsPerChannel
+
+
+/*****************************************************************************
+ * aout_sys_t: private audio output method descriptor
+ *****************************************************************************
+ * This structure is part of the audio output thread descriptor.
+ * It describes the CoreAudio specific properties of an output thread.
+ *****************************************************************************/
+struct aout_sys_t
+{
+    AudioDeviceID               i_default_dev;  /* Keeps DeviceID of defaultOutputDevice */
+    AudioDeviceID               i_selected_dev; /* Keeps DeviceID of the selected device */
+    UInt32                      i_devices;      /* Number of CoreAudio Devices */
+    vlc_bool_t                  b_supports_digital;/* Does the currently selected device support digital mode? */
+    vlc_bool_t                  b_digital;      /* Are we running in digital mode? */
+    Component                   au_component;   /* The Audiocomponent we use */
+    AudioUnit                   au_unit;        /* The AudioUnit we use */
+    mtime_t                     clock_diff;
+};
+
+/*****************************************************************************
+ * Local prototypes.
+ *****************************************************************************/
+static int      Open                    ( vlc_object_t * );
+static void     Close                   ( vlc_object_t * );
+
+static void     Play                    ( aout_instance_t *);
+
+static int      DevicesList             ( aout_instance_t * );
+static int      DeviceDigitalMode       ( aout_instance_t *, AudioDeviceID );
+static int      DigitalInit             ( aout_instance_t * );
+
+static OSStatus RenderCallbackAnalog    ( vlc_object_t *, AudioUnitRenderActionFlags *, const AudioTimeStamp *,
+                                          unsigned int, unsigned int, AudioBufferList *);
+static OSStatus HardwareListener        ( AudioHardwarePropertyID, void *);
+
+/*****************************************************************************
+ * Module descriptor
+ *****************************************************************************/
+#define ADEV_TEXT N_("Audio Device")
+#define ADEV_LONGTEXT N_("Choose a number corresponding to the number of an " \
+    "audio device, as listed in your 'Audio Device' menu. This device will " \
+    "then be used by default for audio playback.")
+
+vlc_module_begin();
+    set_shortname( "auhal" );
+    set_description( _("HAL AudioUnit output") );
+    set_capability( "audio output", 50 );
+    set_category( CAT_AUDIO );
+    set_subcategory( SUBCAT_AUDIO_AOUT );
+    set_callbacks( Open, Close );
+    //add_integer( "coreaudio-dev", -1, NULL, ADEV_TEXT, ADEV_LONGTEXT, VLC_FALSE ); 
+vlc_module_end();
+
+/*****************************************************************************
+ * Open: open a HAL AudioUnit
+ *****************************************************************************/
+static int Open( vlc_object_t * p_this )
+{
+    OSStatus                err = noErr;
+    ComponentDescription    desc;
+    UInt32                  i_param_size,i;
+    struct aout_sys_t       *p_sys;
+    vlc_value_t             val;
+    aout_instance_t         *p_aout = (aout_instance_t *)p_this;
+
+    /* Allocate structure */
+    p_sys = (struct aout_sys_t *)malloc( sizeof( struct aout_sys_t ) );
+    if( p_sys == NULL )
+    {
+        msg_Err( p_aout, "out of memory" );
+        return( VLC_ENOMEM );
+    }
+
+    memset( p_sys, 0, sizeof( struct aout_sys_t ) );
+
+    p_sys->b_digital = VLC_FALSE; /* We assume we are not digital */
+
+    p_aout->output.p_sys = p_sys;
+    p_aout->output.pf_play = Play;
+    
+    aout_FormatPrint( p_aout, "VLC is looking for:\n", (audio_sample_format_t *)&p_aout->output.output );
+    
+    /* Build a list of devices */
+    if( var_Type( p_aout, "audio-device" ) == 0 )
+    {
+        DevicesList( p_aout );
+        /*if( DevicesList( p_aout ) != VLC_SUCCESS );
+        {
+            msg_Err( p_aout, "DevicesList failed" );
+            free( p_sys );
+            return VLC_EGENERIC;
+        }*/
+    }
+    
+    /* What device do we want? */
+    if( var_Get( p_aout, "audio-device", &val ) < 0 )
+    {
+        msg_Err( p_aout, "audio-device var does not exist" );
+        free( p_sys );
+        return( VLC_ENOVAR );
+    }
+    p_sys->i_selected_dev = val.i_int;
+
+    /* what is vlc format? if digital, take digital route else AUHAL route */
+    DeviceDigitalMode( p_aout, p_sys->i_selected_dev );
+    /*if( DeviceDigitalMode( p_aout, p_sys->i_selected_dev ) != VLC_SUCCESS );
+    {
+        msg_Err( p_aout, "DeviceDigitalMode failed" );
+        free( p_sys );
+        return VLC_EGENERIC;
+    }
+    */
+    if( AOUT_FMT_NON_LINEAR( &p_aout->output.output ) && p_sys->b_supports_digital )
+    {
+        p_sys->b_digital = VLC_TRUE;
+        p_aout->output.output.i_format = VLC_FOURCC('s','p','d','i');
+        msg_Dbg( p_aout, "we found a digital stream, and we WANT a digital stream" );
+    }
+    else if( AOUT_FMT_NON_LINEAR( &p_aout->output.output ) && !p_sys->b_supports_digital )
+    {
+        msg_Dbg( p_aout, "we had requested a digital stream, but it's not possible for this device" );
+    }
+ 
+    /* If analog only start setting up AUHAL */
+
+    /* Lets go find our Component */
+    desc.componentType = kAudioUnitType_Output;
+    desc.componentSubType = kAudioUnitSubType_HALOutput;
+    desc.componentManufacturer = kAudioUnitManufacturer_Apple;
+    desc.componentFlags = 0;
+    desc.componentFlagsMask = 0;
+
+    p_sys->au_component = FindNextComponent( NULL, &desc );
+    if( p_sys->au_component == NULL )
+    {
+        msg_Err( p_aout, "we cannot find our HAL component" );
+        free( p_sys );
+        return VLC_EGENERIC;
+    }
+
+    err = OpenAComponent( p_sys->au_component, &p_sys->au_unit );
+    if( err )
+    {
+        
+        msg_Err( p_aout, "we cannot find our HAL component" );
+        free( p_sys );
+        return VLC_EGENERIC;
+    }
+    
+    /* Enable IO for the component */
+    
+    /* Set the device */
+    verify_noerr( AudioUnitSetProperty( p_sys->au_unit,
+                         kAudioOutputUnitProperty_CurrentDevice,
+                         kAudioUnitScope_Global,
+                         0,
+                         &p_sys->i_selected_dev,
+                         sizeof(p_sys->i_selected_dev)));
+                         
+    /* Get the current format */
+    AudioStreamBasicDescription DeviceFormat;
+    
+    i_param_size = sizeof(AudioStreamBasicDescription);
+
+    verify_noerr( AudioUnitGetProperty( p_sys->au_unit,
+                                   kAudioUnitProperty_StreamFormat,
+                                   kAudioUnitScope_Input,
+                                   0,
+                                   &DeviceFormat,
+                                   &i_param_size ));
+                                   
+    msg_Dbg( p_aout, STREAM_FORMAT_MSG( "current format is " , DeviceFormat ) );
+
+    /* Get the channel layout */
+    AudioChannelLayout *layout;
+    verify_noerr( AudioUnitGetPropertyInfo( p_sys->au_unit,
+                                   kAudioDevicePropertyPreferredChannelLayout,
+                                   kAudioUnitScope_Output,
+                                   0,
+                                   &i_param_size,
+                                   NULL ));
+
+    layout = (AudioChannelLayout *)malloc( i_param_size);
+
+    verify_noerr( AudioUnitGetProperty( p_sys->au_unit,
+                                   kAudioDevicePropertyPreferredChannelLayout,
+                                   kAudioUnitScope_Output,
+                                   0,
+                                   layout,
+                                   &i_param_size ));
+                                   
+    /* Lets fill out the ChannelLayout */
+    if( layout->mChannelLayoutTag == kAudioChannelLayoutTag_UseChannelBitmap)
+    {
+        msg_Dbg( p_aout, "bitmap defined channellayout" );
+        verify_noerr( AudioFormatGetProperty( kAudioFormatProperty_ChannelLayoutForBitmap,
+                                sizeof( UInt32), &layout->mChannelBitmap,
+                                &i_param_size,
+                                layout ));
+    }
+    else if( layout->mChannelLayoutTag != kAudioChannelLayoutTag_UseChannelDescriptions )
+    {
+        msg_Dbg( p_aout, "layouttags defined channellayout" );
+        verify_noerr( AudioFormatGetProperty( kAudioFormatProperty_ChannelLayoutForTag,
+                                sizeof( AudioChannelLayoutTag ), &layout->mChannelLayoutTag,
+                                &i_param_size,
+                                layout ));
+    }
+    
+    msg_Dbg( p_aout, "Layout of AUHAL has %d channels" , (int)layout->mNumberChannelDescriptions );
+    
+    p_aout->output.output.i_physical_channels = 0;
+    for( i = 0; i < layout->mNumberChannelDescriptions; i++ )
+    {
+        msg_Dbg( p_aout, "This is channel: %d", (int)layout->mChannelDescriptions[i].mChannelLabel );
+
+        switch( layout->mChannelDescriptions[i].mChannelLabel )
+        {
+            case kAudioChannelLabel_Left:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_LEFT;
+                continue;
+            case kAudioChannelLabel_Right:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_RIGHT;
+                continue;
+            case kAudioChannelLabel_Center:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_CENTER;
+                continue;
+            case kAudioChannelLabel_LFEScreen:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_LFE;
+                continue;
+            case kAudioChannelLabel_LeftSurround:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_REARLEFT;
+                continue;
+            case kAudioChannelLabel_RightSurround:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_REARRIGHT;
+                continue;
+            case kAudioChannelLabel_LeftCenter:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_MIDDLELEFT;
+                continue;
+            case kAudioChannelLabel_RightCenter:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_MIDDLERIGHT;
+                continue;
+            case kAudioChannelLabel_CenterSurround:
+                p_aout->output.output.i_physical_channels |= AOUT_CHAN_REARCENTER;
+                continue;
+            default:
+                msg_Warn( p_aout, "Unrecognized channel form provided by driver: %d", (int)layout->mChannelDescriptions[i].mChannelLabel );
+                p_aout->output.output.i_physical_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
+                break;
+        }
+    }
+    free( layout );
+
+    msg_Dbg( p_aout, "defined %d physical channels for vlc core", aout_FormatNbChannels( &p_aout->output.output ) );
+    msg_Dbg( p_aout, "%s", aout_FormatPrintChannels( &p_aout->output.output ));
+
+    /* Set up the format to be used */
+    DeviceFormat.mSampleRate = p_aout->output.output.i_rate;
+    DeviceFormat.mFormatID = kAudioFormatLinearPCM;
+
+    /* We use float 32. It's the best supported format by both VLC and Coreaudio */
+    p_aout->output.output.i_format = VLC_FOURCC( 'f','l','3','2');
+    DeviceFormat.mFormatFlags = kAudioFormatFlagsNativeFloatPacked;
+    DeviceFormat.mBitsPerChannel = 32;
+    DeviceFormat.mChannelsPerFrame = aout_FormatNbChannels( &p_aout->output.output );
+    
+    /* Calculate framesizes and stuff */
+    aout_FormatPrepare( &p_aout->output.output );
+    DeviceFormat.mBytesPerFrame = p_aout->output.output.i_bytes_per_frame;
+    DeviceFormat.mFramesPerPacket = p_aout->output.output.i_frame_length;
+    DeviceFormat.mBytesPerPacket = p_aout->output.output.i_bytes_per_frame * p_aout->output.output.i_frame_length;
+ 
+    i_param_size = sizeof(AudioStreamBasicDescription);
+    /* Set desired format (Use CAStreamBasicDescription )*/
+    verify_noerr( AudioUnitSetProperty( p_sys->au_unit,
+                                   kAudioUnitProperty_StreamFormat,
+                                   kAudioUnitScope_Input,
+                                   0,
+                                   &DeviceFormat,
+                                   i_param_size ));
+                                   
+    msg_Dbg( p_aout, STREAM_FORMAT_MSG( "we set the AU format: " , DeviceFormat ) );
+    
+    /* Retrieve actual format??? */
+    verify_noerr( AudioUnitGetProperty( p_sys->au_unit,
+                                   kAudioUnitProperty_StreamFormat,
+                                   kAudioUnitScope_Input,
+                                   0,
+                                   &DeviceFormat,
+                                   &i_param_size ));
+                                   
+    msg_Dbg( p_aout, STREAM_FORMAT_MSG( "the actual set AU format is " , DeviceFormat ) );
+    
+    p_aout->output.i_nb_samples = 69 * p_aout->output.output.i_frame_length;
+    aout_VolumeSoftInit( p_aout );
+
+    /* Let's pray for the following operation to be atomic... */
+    p_sys->clock_diff = - (mtime_t)
+        AudioConvertHostTimeToNanos( AudioGetCurrentHostTime() ) / 1000; 
+    p_sys->clock_diff += mdate();
+
+    /* set the IOproc callback */
+    AURenderCallbackStruct input;
+    input.inputProc = (AURenderCallback) RenderCallbackAnalog;
+    input.inputProcRefCon = p_aout;
+    
+    verify_noerr( AudioUnitSetProperty( p_sys->au_unit,
+                            kAudioUnitProperty_SetRenderCallback,
+                            kAudioUnitScope_Input,
+                            0, &input, sizeof( input ) ) );
+    
+    /* AU initiliaze */
+    verify_noerr( AudioUnitInitialize(p_sys->au_unit) );
+
+    verify_noerr( AudioOutputUnitStart(p_sys->au_unit) );
+
+    return( VLC_SUCCESS );
+}
+
+/*****************************************************************************
+ * Close: Close HAL AudioUnit
+ *****************************************************************************/
+static void Close( vlc_object_t * p_this )
+{
+    aout_instance_t     *p_aout = (aout_instance_t *)p_this;
+    struct aout_sys_t   *p_sys = p_aout->output.p_sys;
+    
+    if( p_sys->au_unit )
+    {
+        verify_noerr( AudioOutputUnitStop( p_sys->au_unit ) );
+        verify_noerr( AudioUnitUninitialize( p_sys->au_unit ) );
+        verify_noerr( CloseComponent( p_sys->au_unit ) );
+    }
+    free( p_sys );
+}
+
+/*****************************************************************************
+ * Play: nothing to do
+ *****************************************************************************/
+static void Play( aout_instance_t * p_aout )
+{
+}
+
+
+/*****************************************************************************
+ * DevicesList
+ *****************************************************************************/
+static int DevicesList( aout_instance_t * p_aout )
+{
+    OSStatus            err = noErr;
+    UInt32              i, i_param_size;
+    AudioDeviceID       devid_def;
+    AudioDeviceID       *p_devices = NULL;
+    vlc_value_t         val, text;
+
+    struct aout_sys_t   *p_sys = p_aout->output.p_sys;
+
+    /* Get number of devices */
+    err = AudioHardwareGetPropertyInfo( kAudioHardwarePropertyDevices,
+                                        &i_param_size, NULL );
+    if( err != noErr )
+    {
+        msg_Err( p_aout, "could not get number of devices: [%4.4s]", (char *)&err );
+        goto error;
+    }
+
+    p_sys->i_devices = i_param_size / sizeof( AudioDeviceID );
+
+    if( p_sys->i_devices < 1 )
+    {
+        msg_Err( p_aout, "no devices found" );
+        goto error;
+    }
+
+    msg_Dbg( p_aout, "system has [%ld] device(s)", p_sys->i_devices );
+
+    /* Allocate DeviceID array */
+    p_devices = (AudioDeviceID *)malloc( i_param_size );
+    if( p_devices == NULL )
+    {
+        msg_Err( p_aout, "out of memory" );
+        goto error;
+    }
+
+    /* Populate DeviceID array */
+    err = AudioHardwareGetProperty( kAudioHardwarePropertyDevices,
+                                    &i_param_size, (void *)p_devices );
+    if( err != noErr )
+    {
+        msg_Err( p_aout, "could not get the device ID's: [%4.4s]", (char *)&err );
+        goto error;
+    }
+
+    /* Find the ID of the default Device */
+    i_param_size = sizeof( AudioDeviceID );
+    err = AudioHardwareGetProperty( kAudioHardwarePropertyDefaultOutputDevice,
+                                    &i_param_size, (void *)&devid_def );
+    if( err != noErr )
+    {
+        msg_Err( p_aout, "could not get default audio device: [%4.4s]", (char *)&err );
+        goto error;
+    }
+    p_sys->i_default_dev = devid_def;
+    
+    var_Create( p_aout, "audio-device", VLC_VAR_INTEGER|VLC_VAR_HASCHOICE );
+    text.psz_string = _("Audio Device");
+    var_Change( p_aout, "audio-device", VLC_VAR_SETTEXT, &text, NULL );
+    
+    for( i = 0; i < p_sys->i_devices; i++ )
+    {
+        char psz_devuid[1024];
+        char psz_name[1024];
+        CFStringRef devUID;
+            
+        i_param_size = sizeof psz_name;
+        err = AudioDeviceGetProperty(
+                    p_devices[i], 0, VLC_FALSE,
+                    kAudioDevicePropertyDeviceName,
+                    &i_param_size, psz_name);
+        if( err )
+            goto error;
+
+        i_param_size = sizeof(CFStringRef);    
+        err = AudioDeviceGetProperty(
+                    p_devices[i], 0, VLC_FALSE,
+                    kAudioDevicePropertyDeviceUID,
+                    &i_param_size, &devUID);
+        if( err )
+            goto error;
+
+        CFStringGetCString( devUID, psz_devuid, sizeof psz_devuid, CFStringGetSystemEncoding() );
+        msg_Dbg( p_aout, "DevID: %lu  DevName: %s  DevUID: %s", p_devices[i], psz_name, psz_devuid );
+        CFRelease( devUID );
+
+        val.i_int = (int) p_devices[i];
+        text.psz_string = psz_name;
+        var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val, &text );
+        if( devid_def == p_devices[i] )
+        {
+            var_Change( p_aout, "audio-device", VLC_VAR_SETDEFAULT, &val, NULL );
+            var_Set( p_aout, "audio-device", val );
+        }
+    }
+    var_AddCallback( p_aout, "audio-device", aout_ChannelsRestart, NULL );
+    
+    /* attach a Listener so that we are notified of a change in the Device setup */
+    /*err = AudioHardwareAddPropertyListener( kAudioHardwarePropertyDevices,
+                                            HardwareListener, 
+                                            (void *)p_aout );
+    if( err )
+        goto error;*/
+    
+    msg_Dbg( p_aout, "succesful finish of deviceslist" );
+    if( p_devices ) free( p_devices );
+    return (VLC_SUCCESS);
+
+error:
+    var_Destroy( p_aout, "audio-device" );
+    if( p_devices ) free( p_devices );
+    return VLC_EGENERIC;
+}
+
+/*****************************************************************************
+ * DeviceDigitalMode: Check i_dev_id for digital stream support.
+ *****************************************************************************/
+static int DeviceDigitalMode( aout_instance_t *p_aout, AudioDeviceID i_dev_id )
+{
+    OSStatus                    err = noErr;
+    UInt32                      i_param_size;
+    AudioStreamBasicDescription *p_format_list;
+    int                         i, i_formats;
+    struct aout_sys_t           *p_sys = p_aout->output.p_sys;
+    
+    p_sys->b_supports_digital = VLC_FALSE;
+    
+    err = AudioDeviceGetPropertyInfo( i_dev_id, 0, FALSE,
+                                      kAudioDevicePropertyStreamFormats,
+                                      &i_param_size, NULL );
+    if( err != noErr )
+    {
+        msg_Err( p_aout, "could not get number of streamsformats: [%4.4s]", (char *)&err );
+        return( VLC_EGENERIC );
+    }
+    
+    i_formats = i_param_size / sizeof( AudioStreamBasicDescription );
+    p_format_list = (AudioStreamBasicDescription *)malloc( i_param_size );
+    if( p_format_list == NULL )
+    {
+        return( VLC_ENOMEM );
+    }
+    
+    err = AudioDeviceGetProperty( i_dev_id, 0, FALSE,
+                                      kAudioDevicePropertyStreamFormats,
+                                      &i_param_size, (void *)p_format_list );
+    if( err != noErr )
+    {
+        msg_Err( p_aout, "could not get the list of formats: [%4.4s]", (char *)&err );
+        return( VLC_EGENERIC );
+    }
+
+    for( i = 0; i < i_formats; i++ )
+    {
+        msg_Dbg( p_aout, STREAM_FORMAT_MSG( "supported format", p_format_list[i] ) );
+        
+        if( p_format_list[i].mFormatID == 'IAC3' ||
+                  p_format_list[i].mFormatID == kAudioFormat60958AC3 )
+        {
+            p_sys->b_supports_digital = VLC_TRUE;
+            msg_Dbg( p_aout, "this device supports a digital stream" );
+            break;
+        }
+    }
+    
+    free( (void *)p_format_list );
+    return VLC_SUCCESS;
+}
+
+/*****************************************************************************
+ * RenderCallbackAnalog: This function is called everytime the AudioUnit wants
+ * us to provide some more audio data.
+ *****************************************************************************/
+static OSStatus RenderCallbackAnalog( vlc_object_t *_p_aout,
+                                      AudioUnitRenderActionFlags *ioActionFlags,
+                                      const AudioTimeStamp *inTimeStamp,
+                                      unsigned int inBusNummer,
+                                      unsigned int inNumberFrames,
+                                      AudioBufferList *ioData )
+{
+    aout_buffer_t * p_buffer;
+    AudioTimeStamp  host_time;
+    mtime_t         current_date;
+
+    aout_instance_t * p_aout = (aout_instance_t *)_p_aout;
+    struct aout_sys_t * p_sys = p_aout->output.p_sys;
+msg_Dbg( p_aout, "start audio packet");
+msg_Dbg( p_aout, "inbusnummer: %d",inBusNummer );
+msg_Dbg( p_aout, "inNumberFrames: %d", inNumberFrames);
+
+    host_time.mFlags = kAudioTimeStampHostTimeValid;
+    AudioDeviceTranslateTime( p_sys->i_selected_dev, inTimeStamp, &host_time );
+
+
+    p_sys->clock_diff = - (mtime_t)
+        AudioConvertHostTimeToNanos( AudioGetCurrentHostTime() ) / 1000; 
+    p_sys->clock_diff += mdate();
+
+
+    current_date = (mtime_t) p_sys->clock_diff + mdate() + 
+                     (mtime_t) ( 1000000 * 1 );
+
+#define B_SPDI (p_aout->output.output.i_format == VLC_FOURCC('s','p','d','i'))
+    p_buffer = aout_OutputNextBuffer( p_aout, current_date, VLC_FALSE );
+#undef B_SPDI
+
+msg_Dbg( p_aout, "start audio packet BADABOEM");
+
+    if( p_buffer != NULL )
+    {
+        if( ioData != NULL && ioData->mNumberBuffers > 0 )
+        {
+            if( p_buffer->i_nb_bytes*8 != ioData->mBuffers[0].mDataByteSize )
+            {
+                msg_Dbg( p_aout, "byte sizes don't match %d:%d", p_buffer->i_nb_bytes*8, ioData->mBuffers[0].mDataByteSize);
+            }
+            else
+            {
+                unsigned int i;
+                /* move data into output data buffer */
+                msg_Dbg( p_aout, "#buffers: %d", (int)ioData->mNumberBuffers );
+                for( i = 0; i < ioData->mNumberBuffers; i++ )
+                {
+                    p_aout->p_vlc->pf_memcpy( ioData->mBuffers[i].mData,
+                                      p_buffer->p_buffer, ioData->mBuffers[i].mDataByteSize );
+                }
+                msg_Dbg( p_aout, "yeah first:" );
+                aout_BufferFree( p_buffer );
+                msg_Dbg( p_aout, "yeah" );
+            }
+        }
+        else msg_Dbg( p_aout, "no iodata or buffers");
+    }
+    else
+    {
+        msg_Dbg( p_aout, "aout_OutputNextBuffer failed" ); 
+        if( p_aout->output.output.i_format == VLC_FOURCC('f','l','3','2') )
+        {
+            UInt32 i;
+            float * p = (float *)ioData->mBuffers[0].mData;
+
+            for( i = 0; i < ioData->mBuffers[0].mDataByteSize; i++ )
+            {
+                *p++ = 0.0;
+            }
+        }
+        else
+        {
+            p_aout->p_vlc->pf_memset( ioData->mBuffers[0].mData, 0, ioData->mBuffers[0].mDataByteSize );
+        }
+    }
+msg_Dbg( p_aout, "eof audio packet");
+    return( noErr );     
+}
+
+
+/*****************************************************************************
+ * Setup a digital stream
+ *****************************************************************************/
+static int DigitalInit( aout_instance_t * p_aout )
+{
+    OSStatus            err = noErr;
+    UInt32              i, i_param_size;
+    AudioDeviceID       devid_def;
+    AudioDeviceID       *p_devices = NULL;
+    vlc_value_t         val, text;
+
+    struct aout_sys_t   *p_sys = p_aout->output.p_sys;
+
+    
+    
+    return (VLC_SUCCESS);
+
+error:
+    return VLC_EGENERIC;
+}
+
+
+/*****************************************************************************
+ * HardwareListener: Warns us of changes in the list of registered devices
+ *****************************************************************************/
+static OSStatus HardwareListener( AudioHardwarePropertyID inPropertyID,
+                                  void * inClientData )
+{
+    OSStatus err = noErr;
+
+    aout_instance_t     *p_aout = (aout_instance_t *)inClientData;
+    /* struct aout_sys_t   *p_sys = p_aout->output.p_sys; */
+
+    switch( inPropertyID )
+    {
+        case kAudioHardwarePropertyDevices:
+        {
+            /* something changed in the list of devices */
+            /* We trigger the audio-device's aout_ChannelsRestart callback */
+            var_Change( p_aout, "audio-device", VLC_VAR_TRIGGER_CALLBACKS, NULL, NULL );
+        }
+        break;
+    }
+
+    return( err );
+}