Ticket #11: portaudio-deviceschanged.patch

test/patest2.c

@@ +1 @@
+/** @file patest2.c
+    @ingroup test_src
+    @brief Ring modulate the audio input with a sine wave for 20 seconds with
+    device change detection.
+    @author Ross Bencina <rossb@audiomulch.com>, 
+            Phil Burk http://www.softsynth.com,
+            Erik Bunce <kde@bunce.us>
+*/
+/*
+ * $Id$
+ *
+ * This program uses the PortAudio Portable Audio Library.
+ * For more information see: http://www.portaudio.com
+ * Copyright (c) 1999-2000 Ross Bencina and Phil Burk
+ *
+ * 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.
+ */
+
+/*
+ * The text above constitutes the entire PortAudio license; however, 
+ * the PortAudio community also makes the following non-binding requests:
+ *
+ * Any person wishing to distribute modifications to the Software is
+ * requested to send the modifications to the original developer so that
+ * they can be incorporated into the canonical version. It is also 
+ * requested that these non-binding requests be included along with the 
+ * license above.
+ */
+
+#include <stdio.h>
+#include <math.h>
+#include "portaudio.h"
+
+#ifndef M_PI
+#define M_PI (3.14159265)
+#endif
+
+#define SAMPLE_RATE (44100)
+
+typedef struct
+{
+    float sine[100];
+    int phase;
+    int sampsToGo;
+}
+patest1data;
+
+static void patest1DevicesChangedCallback( PaDevicesChangedFlags flags, 
+                                           void *userData )
+{
+    int     i, numDevices, defaultDisplayed;
+    const   PaDeviceInfo *deviceInfo;
+    printf( "========================================\n" );
+    printf( "patest1DevicesChangedCallback(%04x, %p)\n", flags, userData );
+    numDevices = Pa_GetDeviceCount();
+
+    if( numDevices < 0 )
+    {
+        printf( "ERROR: Pa_CountDevices returned 0x%x\n", numDevices );
+        return;
+    }
+    
+    if ( ( flags & paDefaultInputDeviceChanged ) )
+    {
+        i = Pa_GetDefaultInputDevice();
+
+        deviceInfo = Pa_GetDeviceInfo( i );
+        if ( deviceInfo != NULL)
+            printf( "Default input device changed to %d: %s (%s)\n", i, deviceInfo->name, Pa_GetHostApiInfo( deviceInfo->hostApi )->name );
+        else
+            printf( "Default input device changed to %d\n", i );
+    }
+
+
+    if ( ( flags & paDefaultOutputDeviceChanged ) )
+    {
+        i = Pa_GetDefaultOutputDevice();
+
+        deviceInfo = Pa_GetDeviceInfo( i );
+        if ( deviceInfo )
+            printf( "Default output device changed to %d: %s (%s)\n", i, deviceInfo->name, Pa_GetHostApiInfo( deviceInfo->hostApi )->name );
+        else
+            printf( "Default output device changed to %d\n", i );
+    }
+
+    /* only display the new list if the list has already changed */
+    if ( ( flags & paDevicesListChanged ) == 0 )
+        return;
+
+    printf( "Hardware device list changed\n" );
+        
+    printf( "Number of devices = %d\n", numDevices );
+    for( i=0; i<numDevices; i++ )
+    {
+        deviceInfo = Pa_GetDeviceInfo( i );
+        printf( "--------------------------------------- device #%d\n", i );
+                
+    /* Mark global and API specific default devices */
+        defaultDisplayed = 0;
+        if( i == Pa_GetDefaultInputDevice() )
+        {
+            printf( "[ Default Input" );
+            defaultDisplayed = 1;
+        }
+        else if( i == Pa_GetHostApiInfo( deviceInfo->hostApi )->defaultInputDevice )
+        {
+            const PaHostApiInfo *hostInfo = Pa_GetHostApiInfo( deviceInfo->hostApi );
+            printf( "[ Default %s Input", hostInfo->name );
+            defaultDisplayed = 1;
+        }
+        
+        if( i == Pa_GetDefaultOutputDevice() )
+        {
+            printf( (defaultDisplayed ? "," : "[") );
+            printf( " Default Output" );
+            defaultDisplayed = 1;
+        }
+        else if( i == Pa_GetHostApiInfo( deviceInfo->hostApi )->defaultOutputDevice )
+        {
+            const PaHostApiInfo *hostInfo = Pa_GetHostApiInfo( deviceInfo->hostApi );
+            printf( (defaultDisplayed ? "," : "[") );                
+            printf( " Default %s Output", hostInfo->name );
+            defaultDisplayed = 1;
+        }
+
+        if( defaultDisplayed )
+            printf( " ]\n" );
+
+    /* print device info fields */
+        printf( "Name                        = %s\n", deviceInfo->name );
+        printf( "Host API                    = %s\n",  Pa_GetHostApiInfo( deviceInfo->hostApi )->name );
+        printf( "Max inputs = %d", deviceInfo->maxInputChannels  );
+        printf( ", Max outputs = %d\n", deviceInfo->maxOutputChannels  );
+
+        printf( "Default low input latency   = %8.3f\n", deviceInfo->defaultLowInputLatency  );
+        printf( "Default low output latency  = %8.3f\n", deviceInfo->defaultLowOutputLatency  );
+        printf( "Default high input latency  = %8.3f\n", deviceInfo->defaultHighInputLatency  );
+        printf( "Default high output latency = %8.3f\n", deviceInfo->defaultHighOutputLatency  );
+    }
+}
+
+static int patest1Callback( const void *inputBuffer, void *outputBuffer,
+                            unsigned long framesPerBuffer,
+                            const PaStreamCallbackTimeInfo* timeInfo,
+                            PaStreamCallbackFlags statusFlags,
+                            void *userData )
+{
+    patest1data *data = (patest1data*)userData;
+    float *in = (float*)inputBuffer;
+    float *out = (float*)outputBuffer;
+    int framesToCalc = framesPerBuffer;
+    unsigned long i = 0;
+    int finished;
+
+    if( data->sampsToGo < framesPerBuffer )
+    {
+        framesToCalc = data->sampsToGo;
+        finished = paComplete;
+    }
+    else
+    {
+        finished = paContinue;
+    }
+
+    for( ; i<framesToCalc; i++ )
+    {
+        *out++ = *in++ * data->sine[data->phase];  /* left */
+        *out++ = *in++ * data->sine[data->phase++];  /* right */
+        if( data->phase >= 100 )
+            data->phase = 0;
+    }
+
+    data->sampsToGo -= framesToCalc;
+
+    /* zero remainder of final buffer if not already done */
+    for( ; i<framesPerBuffer; i++ )
+    {
+        *out++ = 0; /* left */
+        *out++ = 0; /* right */
+    }
+    
+    return finished;
+}
+
+int main(int argc, char* argv[]);
+int main(int argc, char* argv[])
+{
+    PaStream                *stream;
+    PaError                 err;
+    patest1data             data;
+    int                     i;
+    PaStreamParameters      inputParameters, outputParameters;
+    const PaHostErrorInfo*  herr;
+
+    printf("patest1.c\n"); fflush(stdout);
+    printf("Ring modulate input for 20 seconds.\n"); fflush(stdout);
+    
+    /* initialise sinusoidal wavetable */
+    for( i=0; i<100; i++ )
+        data.sine[i] = sin( ((double)i/100.) * M_PI * 2. );
+    data.phase = 0;
+    data.sampsToGo = SAMPLE_RATE * 20;        /* 20 seconds. */
+
+    /* initialise portaudio subsytem */
+    err = Pa_Initialize();
+
+    err = Pa_AddDevicesChangedCallback(patest1DevicesChangedCallback, NULL);
+
+    inputParameters.device = Pa_GetDefaultInputDevice();    /* default input device */
+    inputParameters.channelCount = 2;                       /* stereo input */
+    inputParameters.sampleFormat = paFloat32;               /* 32 bit floating point input */
+    inputParameters.suggestedLatency = Pa_GetDeviceInfo( inputParameters.device )->defaultLowInputLatency;
+    inputParameters.hostApiSpecificStreamInfo = NULL;
+
+    outputParameters.device = Pa_GetDefaultOutputDevice();  /* default output device */
+    outputParameters.channelCount = 2;                      /* stereo output */
+    outputParameters.sampleFormat = paFloat32;              /* 32 bit floating point output */
+    outputParameters.suggestedLatency = Pa_GetDeviceInfo( outputParameters.device )->defaultLowOutputLatency;
+    outputParameters.hostApiSpecificStreamInfo = NULL;
+
+    err = Pa_OpenStream(
+                        &stream,
+                        &inputParameters,
+                        &outputParameters,
+                        (double)SAMPLE_RATE, /* Samplerate in Hertz. */
+                        512,                 /* Small buffers */
+                        paClipOff,           /* We won't output out of range samples so don't bother clipping them. */
+                        patest1Callback,
+                        &data );
+    if( err != paNoError ) goto done;
+
+    err = Pa_StartStream( stream );
+    if( err != paNoError ) goto done;
+    
+    printf( "Press any key to end.\n" ); fflush(stdout);
+         
+    getc( stdin ); /* wait for input before exiting */
+
+    err = Pa_AbortStream( stream );
+    if( err != paNoError ) goto done;
+    
+    printf( "Waiting for stream to complete...\n" );
+
+    /* sleep until playback has finished */
+    while( ( err = Pa_IsStreamActive( stream ) ) == 1 ) Pa_Sleep(1000);
+    if( err < 0 ) goto done;
+
+    err = Pa_CloseStream( stream );
+    if( err != paNoError ) goto done;
+
+done:
+    err = Pa_RemoveDevicesChangedCallback(patest1DevicesChangedCallback, NULL);
+
+    Pa_Terminate();
+
+    if( err != paNoError )
+    {
+        fprintf( stderr, "An error occured while using portaudio\n" );
+        if( err == paUnanticipatedHostError )
+        {
+            fprintf( stderr, " unanticipated host error.\n");
+            herr = Pa_GetLastHostErrorInfo();
+            if (herr)
+            {
+                fprintf( stderr, " Error number: %ld\n", herr->errorCode );
+                if (herr->errorText)
+                    fprintf( stderr, " Error text: %s\n", herr->errorText );
+            }
+            else
+                fprintf( stderr, " Pa_GetLastHostErrorInfo() failed!\n" );
+        }
+        else
+        {
+            fprintf( stderr, " Error number: %d\n", err );
+            fprintf( stderr, " Error text: %s\n", Pa_GetErrorText( err ) );
+        }
+
+        err = 1;          /* Always return 0 or 1, but no other return codes. */
+    }
+
+    printf( "bye\n" );
+
+    return err;
+}

Makefile.in

@@ -59 +59 @@
         bin/paqa_devs \
         bin/paqa_errs \
         bin/patest1 \
+        bin/patest2 \
         bin/patest_buffer \
         bin/patest_callbackstop \
         bin/patest_clip \

include/portaudio.h

@@ -356 +356 @@
 */
 const PaHostErrorInfo* Pa_GetLastHostErrorInfo( void );
 
+/* Device enumeration and capabilities */
 
+/** Flags used to indicate which device states have changed.
+ 
+    @see paDevicesListAboutToBeChanged, paDevicesListChanged,
+    paDefaultInputDeviceChanged, paDefaultOutputDeviceChanged
+*/
+typedef unsigned long PaDevicesChangedFlags;
 
-/* Device enumeration and capabilities */
+/** Indicates that the list of devices is about to be changed.
 
+ This is sent before the list of devices is changed.  All PaDeviceInfo 
+ structures retrieved prior to this notification are about to be freed.
+
+ @see PaDevicesChangedFlags
+*/
+#define paDevicesListAboutToBeChanged   ((PaDevicesChangedFlags) 0x00000001)
+
+/** Indicates that the list of devices has changed.
+
+ This is sent after the PortAudio list of devices has changed.
+ All PaDeviceInfo structures retrieved prior to this notification are now 
+ invalid.
+
+ @see PaDevicesChangedFlags
+*/
+#define paDevicesListChanged            ((PaDevicesChangedFlags) 0x00000002)
+
+/** Indicates that the systems default input device has changed.
+
+ @see PaDevicesChangedFlags
+*/
+#define paDefaultInputDeviceChanged     ((PaDevicesChangedFlags) 0x00000004)
+
+/** Indicates that the systems default output device has changed.
+
+ @see PaDevicesChangedFlags
+*/
+#define paDefaultOutputDeviceChanged    ((PaDevicesChangedFlags) 0x00000008)
+
+/** Functions of type PaDevicesChangedCallback are implemented by PortAudio
+ clients. They can be registered using the Pa_SetDevicesChangedCallback
+ function. Once registered they are called when the state of installed devices
+ changes.
+
+ @param flags The flags indicate what aspects of the known devices has
+ changed.
+ @param userData The userData parameter supplied t Pa_SetDevicesChangedCallback().
+
+ @see Pa_AddDevicesChangedCallback, Pa_RemoveDevicesChangedCallback, 
+ PaDevicesChangedFlags
+ */
+typedef void PaDevicesChangedCallback( PaDevicesChangedFlags flags, 
+                                       void *userData );
+
+/** Add a devices changed callback function which will be called when the 
+ the state of installed devices changes.
+
+ @note If no callback is registered the traditional behavior of ignoring devices
+ changes is maintained. However, if a callback is registered then PortAudio 
+ will automatically rescan the set of available devices when a change is detected.
+ This is done in an attempt to maintain backwards compatibility for older 
+ clients.
+
+ @param userData A client supplied pointer which is passed to the stream callback
+ function. It could for example, contain a pointer to instance data necessary for
+ processing device change notifications.
+*/
+PaError Pa_AddDevicesChangedCallback( PaDevicesChangedCallback* devicesCallback,
+                                      void *userData );
+
+/** Remove a devices changed callback function which will be called when the 
+ the state of installed devices changes.
+
+ @param userData A client supplied pointer which is passed to the stream callback
+ function. It could for example, contain a pointer to instance data necessary for
+ processing device change notifications.
+*/
+PaError Pa_RemoveDevicesChangedCallback( PaDevicesChangedCallback* devicesCallback,
+                                      void *userData );
+
+/** Rescans the system in order to detect new devices.
+
+ It will call the registered PaDevicesChangedCallback with paDevicesListChanged
+ when it is done.
+
+ @note This will free all PaDeviceInfo structures that may have been returned
+ previously.
+*/
+PaError Pa_RescanDevices( void );
+
 /** Retrieve the number of available devices. The number of available devices
  may be zero.
 
@@ -470 +557 @@
 
  @note PortAudio manages the memory referenced by the returned pointer,
  the client must not manipulate or free the memory. The pointer is only
- guaranteed to be valid between calls to Pa_Initialize() and Pa_Terminate().
+ guaranteed to be valid between calls to Pa_Initialize(), Pa_RescanDevices(),
+ and Pa_Terminate().
 
  @see PaDeviceInfo, PaDeviceIndex
 */

src/hostapi/alsa/pa_linux_alsa.c

@@ -254 +254 @@
     (*hostApi)->info.name = "ALSA";
 
     (*hostApi)->Terminate = Terminate;
+    (*hostApi)->RescanDevices = NULL;
     (*hostApi)->OpenStream = OpenStream;
     (*hostApi)->IsFormatSupported = IsFormatSupported;
 

src/hostapi/oss/pa_unix_oss.c

@@ -250 +250 @@
     (*hostApi)->info.type = paOSS;
     (*hostApi)->info.name = "OSS";
     (*hostApi)->Terminate = Terminate;
+    (*hostApi)->RescanDevices = NULL;
     (*hostApi)->OpenStream = OpenStream;
     (*hostApi)->IsFormatSupported = IsFormatSupported;
 

src/hostapi/wasapi/pa_win_wasapi.cpp

@@ -635 +635 @@
     spEndpoints->Release();
 
     (*hostApi)->Terminate = Terminate;
+    (*hostApi)->RescanDevices = NULL;
     (*hostApi)->OpenStream = OpenStream;
     (*hostApi)->IsFormatSupported = IsFormatSupported;
 
@@ -1908 +1909 @@
                                 stream->outVol->SetMute(FALSE, NULL);
                                 bFirst = false;
                         }
-#endif
- No newline at end of file
+#endif

src/hostapi/wdmks/pa_win_wdmks.c

@@ -1876 +1876 @@
     (*hostApi)->info.deviceCount = deviceCount;
 
     (*hostApi)->Terminate = Terminate;
+    (*hostApi)->RescanDevices = NULL;
     (*hostApi)->OpenStream = OpenStream;
     (*hostApi)->IsFormatSupported = IsFormatSupported;
 
@@ -3280 +3281 @@
     /* IMPLEMENT ME, see portaudio.h for required behavior*/
     PA_LOGL_;
     return 0;
-}
- No newline at end of file
+}

src/hostapi/wmme/pa_win_wmme.c

@@ -1040 +1040 @@
     InitializeDefaultDeviceIdsFromEnv( winMmeHostApi );
 
     (*hostApi)->Terminate = Terminate;
+    (*hostApi)->RescanDevices = NULL;
     (*hostApi)->OpenStream = OpenStream;
     (*hostApi)->IsFormatSupported = IsFormatSupported;
 

src/hostapi/jack/pa_jack.c

@@ -746 +746 @@
     /* Register functions */
 
     (*hostApi)->Terminate = Terminate;
+    (*hostApi)->RescanDevices = NULL;
     (*hostApi)->OpenStream = OpenStream;
     (*hostApi)->IsFormatSupported = IsFormatSupported;
 

src/hostapi/coreaudio/pa_mac_core.c

@@ -70 +70 @@
 #include "pa_mac_core.h"
 #include "pa_mac_core_utilities.h"
 #include "pa_mac_core_blocking.h"
+#include "pa_debugprint.h"
 
 
 #ifdef __cplusplus
@@ -227 +228 @@
 #define RING_BUFFER_ADVANCE_DENOMINATOR (4)
 
 static void Terminate( struct PaUtilHostApiRepresentation *hostApi );
+static PaError RescanDevices( struct PaUtilHostApiRepresentation *hostApi );
 static PaError IsFormatSupported( struct PaUtilHostApiRepresentation *hostApi,
                                   const PaStreamParameters *inputParameters,
                                   const PaStreamParameters *outputParameters,
@@ -324 +326 @@
       sfc( stream->streamRepresentation.userData );
 }
 
-
-/*currently, this is only used in initialization, but it might be modified
-  to be used when the list of devices changes.*/
-static PaError gatherDeviceInfo(PaMacAUHAL *auhalHostApi)
+/* This is used during initialization, rescan, and default device changes to 
+ gather information about the current default input device. */
+static void gatherDefaultInputDevice(PaMacAUHAL *auhalHostApi)
 {
-    UInt32 size;
-    UInt32 propsize;
-    VVDBUG(("gatherDeviceInfo()\n"));
-    /* -- free any previous allocations -- */
-    if( auhalHostApi->devIds )
-        PaUtil_GroupFreeMemory(auhalHostApi->allocations, auhalHostApi->devIds);
-    auhalHostApi->devIds = NULL;
-
-    /* -- figure out how many devices there are -- */
-    AudioHardwareGetPropertyInfo( kAudioHardwarePropertyDevices,
-                                  &propsize,
-                                  NULL );
-    auhalHostApi->devCount = propsize / sizeof( AudioDeviceID );
-
-    VDBUG( ( "Found %ld device(s).\n", auhalHostApi->devCount ) );
-
-    /* -- copy the device IDs -- */
-    auhalHostApi->devIds = (AudioDeviceID *)PaUtil_GroupAllocateMemory(
-                             auhalHostApi->allocations,
-                             propsize );
-    if( !auhalHostApi->devIds )
-        return paInsufficientMemory;
-    AudioHardwareGetProperty( kAudioHardwarePropertyDevices,
-                                  &propsize,
-                                  auhalHostApi->devIds );
-#ifdef MAC_CORE_VERBOSE_DEBUG
-    {
-       int i;
-       for( i=0; i<auhalHostApi->devCount; ++i )
-          printf( "Device %d\t: %ld\n", i, auhalHostApi->devIds[i] );
-    }
-#endif
-
-    size = sizeof(AudioDeviceID);
+    UInt32 size = sizeof(AudioDeviceID);
+    VVDBUG(("gatherDefaultInputDevice()\n"));
     auhalHostApi->defaultIn  = kAudioDeviceUnknown;
-    auhalHostApi->defaultOut = kAudioDeviceUnknown;
 
     /* determine the default device. */
     /* I am not sure how these calls to AudioHardwareGetProperty()
@@ -385 +353 @@
                 auhalHostApi->defaultIn = auhalHostApi->devIds[i];
                 break;
              }
-       }
+      }
     }   
+    VDBUG( ( "Default in : %ld\n", auhalHostApi->defaultIn  ) );
+}
+
+/* This is used during initialization, rescan, and default device changes to 
+ gather information about the current default output device. */
+static void gatherDefaultOutputDevice(PaMacAUHAL *auhalHostApi)
+{
+    UInt32 size = sizeof(AudioDeviceID);
+    VVDBUG(("gatherDefaultOutputDevice()\n"));
+    auhalHostApi->defaultOut = kAudioDeviceUnknown;
+
     if( 0 != AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice,
                      &size,
                      &auhalHostApi->defaultOut) ) {
@@ -404 +383 @@
              }
        }
     }   
-
-    VDBUG( ( "Default in : %ld\n", auhalHostApi->defaultIn  ) );
     VDBUG( ( "Default out: %ld\n", auhalHostApi->defaultOut ) );
+}
 
+/* This is used during initialization and rescan to gather information about 
+ devices. */
+static PaError gatherDeviceInfo(PaMacAUHAL *auhalHostApi)
+{
+    UInt32 size;
+    UInt32 propsize;
+    VVDBUG(("gatherDeviceInfo()\n"));
+    /* -- free any previous allocations -- */
+    if( auhalHostApi->devIds )
+        PaUtil_GroupFreeMemory(auhalHostApi->allocations, auhalHostApi->devIds);
+    auhalHostApi->devIds = NULL;
+
+    /* -- figure out how many devices there are -- */
+    AudioHardwareGetPropertyInfo( kAudioHardwarePropertyDevices,
+                                  &propsize,
+                                  NULL );
+    auhalHostApi->devCount = propsize / sizeof( AudioDeviceID );
+
+    VDBUG( ( "Found %ld device(s).\n", auhalHostApi->devCount ) );
+
+    /* -- copy the device IDs -- */
+    auhalHostApi->devIds = (AudioDeviceID *)PaUtil_GroupAllocateMemory(
+                             auhalHostApi->allocations,
+                             propsize );
+    if( !auhalHostApi->devIds )
+        return paInsufficientMemory;
+    AudioHardwareGetProperty( kAudioHardwarePropertyDevices,
+                                  &propsize,
+                                  auhalHostApi->devIds );
+#ifdef MAC_CORE_VERBOSE_DEBUG
+    {
+       int i;
+       for( i=0; i<auhalHostApi->devCount; ++i )
+          printf( "Device %d\t: %ld\n", i, auhalHostApi->devIds[i] );
+    }
+#endif
+
+    gatherDefaultInputDevice(auhalHostApi);
+    gatherDefaultOutputDevice(auhalHostApi);
+
     return paNoError;
 }
 
+/* Callback for audio hardware property changes. */
+static OSStatus audioPropertyCallback(AudioHardwarePropertyID inPropertyID, 
+                                      void *refCon)
+{
+    struct PaUtilHostApiRepresentation *hostApi = 
+        (struct PaUtilHostApiRepresentation *)refCon;
+    PaMacAUHAL *auhalHostApi = (PaMacAUHAL*)hostApi;
+    int i;
+    switch (inPropertyID)
+    {
+        /*
+         * These are the other types of notifications we might receive, however, they are beyond
+         * the scope of this sample and we ignore them.
+         **/
+    case kAudioHardwarePropertyDefaultInputDevice:
+        PA_DEBUG(("audioPropertyCallback: default input device changed\n"));
+
+        /* default to no device, in case we don't find it in the devIds. */
+        hostApi->info.defaultInputDevice = paNoDevice;
+        
+        gatherDefaultInputDevice(auhalHostApi);
+        
+        /* attempt to find the device amongst the known devIds. */
+        for( i=0; i < auhalHostApi->devCount; ++i )
+        {
+            if (auhalHostApi->devIds[i] == auhalHostApi->defaultIn)
+                hostApi->info.defaultInputDevice = i;
+        }
+
+        PaUtil_DevicesChanged( paDefaultInputDeviceChanged );
+        break;
+        
+    case kAudioHardwarePropertyDefaultOutputDevice:
+        PA_DEBUG(("audioPropertyCallback: default output device changed\n"));
+
+        /* default to no device, in case we don't find it in the devIds. */
+        hostApi->info.defaultOutputDevice = paNoDevice;
+
+        gatherDefaultOutputDevice(auhalHostApi);
+
+        /* attempt to find the device amongst the known devIds. */
+        for( i=0; i < auhalHostApi->devCount; ++i )
+        {
+            if (auhalHostApi->devIds[i] == auhalHostApi->defaultOut)
+                hostApi->info.defaultOutputDevice = i;
+        }
+
+        PaUtil_DevicesChanged( paDefaultOutputDeviceChanged );
+        break;
+        
+    case kAudioHardwarePropertyDefaultSystemOutputDevice:
+        PA_DEBUG(("audioPropertyCallback: default system output device changed\n"));
+        break;
+        
+    case kAudioHardwarePropertyDevices:
+        PA_DEBUG(("audioPropertyCallback: device list changed\n"));
+        PaUtil_DevicesChanged( paUtilHardwareDevicesChanged );
+        break;
+        
+    default:
+        PA_DEBUG(("audioPropertyCallback: unknown message id=%08lx\n", inPropertyID));
+        break;
+    }
+    
+    return noErr;
+}
+
 static PaError GetChannelInfo( PaMacAUHAL *auhalHostApi,
                                PaDeviceInfo *deviceInfo,
                                AudioDeviceID macCoreDeviceId,
@@ -626 +711 @@
     }
 
     (*hostApi)->Terminate = Terminate;
+    (*hostApi)->RescanDevices = RescanDevices;
     (*hostApi)->OpenStream = OpenStream;
     (*hostApi)->IsFormatSupported = IsFormatSupported;
 
@@ -647 +733 @@
                                       GetStreamReadAvailable,
                                       GetStreamWriteAvailable );
 
+    /* register the audio hardware change listener */
+    AudioHardwareAddPropertyListener(kAudioHardwarePropertyDevices, 
+                                     audioPropertyCallback, *hostApi);
+    AudioHardwareAddPropertyListener(kAudioHardwarePropertyDefaultInputDevice, 
+                                     audioPropertyCallback, *hostApi);
+    AudioHardwareAddPropertyListener(kAudioHardwarePropertyDefaultOutputDevice, 
+                                     audioPropertyCallback, *hostApi);
+    
     return result;
 
 error:
@@ -676 +770 @@