diff src/audio/macosx/SDL_coreaudio.c @ 2049:5f6550e5184f

Merged SDL-ryan-multiple-audio-device branch r2803:2871 into the trunk.
author Ryan C. Gordon <icculus@icculus.org>
date Tue, 17 Oct 2006 09:15:21 +0000
parents adf732f1f016
children 72cc2226d6a3
line wrap: on
line diff
--- a/src/audio/macosx/SDL_coreaudio.c	Sun Oct 01 16:10:41 2006 +0000
+++ b/src/audio/macosx/SDL_coreaudio.c	Tue Oct 17 09:15:21 2006 +0000
@@ -21,6 +21,7 @@
 */
 #include "SDL_config.h"
 
+#include <CoreAudio/CoreAudio.h>
 #include <AudioUnit/AudioUnit.h>
 
 #include "SDL_audio.h"
@@ -28,79 +29,233 @@
 #include "../SDL_sysaudio.h"
 #include "SDL_coreaudio.h"
 
-
-/* Audio driver functions */
+#define DEBUG_COREAUDIO 0
 
-static int Core_OpenAudio(_THIS, SDL_AudioSpec * spec);
-static void Core_WaitAudio(_THIS);
-static void Core_PlayAudio(_THIS);
-static Uint8 *Core_GetAudioBuf(_THIS);
-static void Core_CloseAudio(_THIS);
+typedef struct COREAUDIO_DeviceList
+{
+    AudioDeviceID id;
+    const char *name;
+} COREAUDIO_DeviceList;
 
-/* Audio driver bootstrap functions */
-
-static int
-Audio_Available(void)
-{
-    return (1);
-}
+static COREAUDIO_DeviceList *inputDevices = NULL;
+static int inputDeviceCount = 0;
+static COREAUDIO_DeviceList *outputDevices = NULL;
+static int outputDeviceCount = 0;
 
 static void
-Audio_DeleteDevice(SDL_AudioDevice * device)
+free_device_list(COREAUDIO_DeviceList **devices, int *devCount)
 {
-    SDL_free(device->hidden);
-    SDL_free(device);
+    if (*devices) {
+        int i = *devCount;
+        while (i--)
+            SDL_free((void *) (*devices)[i].name);
+        SDL_free(*devices);
+        *devices = NULL;
+    }
+    *devCount = 0;
 }
 
-static SDL_AudioDevice *
-Audio_CreateDevice(int devindex)
+
+static void
+build_device_list(int iscapture, COREAUDIO_DeviceList **devices, int *devCount)
 {
-    SDL_AudioDevice *this;
+    Boolean outWritable = 0;
+    OSStatus result = noErr;
+    UInt32 size = 0;
+    AudioDeviceID *devs = NULL;
+    UInt32 i = 0;
+    UInt32 max = 0;
+
+    free_device_list(devices, devCount);
+
+    result = AudioHardwareGetPropertyInfo(kAudioHardwarePropertyDevices,
+                                         &size, &outWritable);
+
+    if (result != kAudioHardwareNoError)
+        return;
+
+    devs = (AudioDeviceID *) alloca(size);
+    if (devs == NULL)
+        return;
+
+    max = size / sizeof (AudioDeviceID);
+    *devices = (COREAUDIO_DeviceList *) SDL_malloc(max * sizeof (**devices));
+    if (*devices == NULL)
+        return;
+
+    result = AudioHardwareGetProperty(kAudioHardwarePropertyDevices,
+                                     &size, devs);
+    if (result != kAudioHardwareNoError)
+        return;
+
+    for (i = 0; i < max; i++) {
+        CFStringRef cfstr = NULL;
+        char *ptr = NULL;
+        AudioDeviceID dev = devs[i];
+        AudioBufferList *buflist = NULL;
+        int usable = 0;
+        CFIndex len = 0;
+
+        result = AudioDeviceGetPropertyInfo(dev, 0, iscapture,
+                                      kAudioDevicePropertyStreamConfiguration,
+                                      &size, &outWritable);
+        if (result != noErr)
+            continue;
+
+        buflist = (AudioBufferList *) SDL_malloc(size);
+        if (buflist == NULL)
+            continue;
+
+        result = AudioDeviceGetProperty(dev, 0, iscapture,
+                                      kAudioDevicePropertyStreamConfiguration,
+                                      &size, buflist);
 
-    /* Initialize all variables that we clean on shutdown */
-    this = (SDL_AudioDevice *) SDL_malloc(sizeof(SDL_AudioDevice));
-    if (this) {
-        SDL_memset(this, 0, (sizeof *this));
-        this->hidden = (struct SDL_PrivateAudioData *)
-            SDL_malloc((sizeof *this->hidden));
+        if (result == noErr) {
+            UInt32 j;
+            for (j = 0; j < buflist->mNumberBuffers; j++) {
+                if (buflist->mBuffers[j].mNumberChannels > 0) {
+                    usable = 1;
+                    break;
+                }
+            }
+        }
+
+        SDL_free(buflist);
+
+        if (!usable)
+            continue;
+
+        size = sizeof (CFStringRef);
+        result = AudioDeviceGetProperty(dev, 0, iscapture,
+                                        kAudioObjectPropertyName,
+                                        &size, &cfstr);
+
+        if (result != kAudioHardwareNoError)
+            continue;
+
+        len = CFStringGetMaximumSizeForEncoding(CFStringGetLength(cfstr),
+                                                kCFStringEncodingUTF8);
+
+        ptr = (char *) SDL_malloc(len + 1);
+        usable = ( (ptr != NULL) &&
+                (CFStringGetCString(cfstr,ptr,len+1,kCFStringEncodingUTF8)) );
+
+        CFRelease(cfstr);
+
+        if (usable) {
+            len = strlen(ptr);
+            /* Some devices have whitespace at the end...trim it. */
+            while ((len > 0) && (ptr[len-1] == ' ')) {
+                len--;
+            }
+            usable = (len > 0);
+        }
+
+        if (!usable) {
+            SDL_free(ptr);
+        } else {
+            ptr[len] = '\0';
+
+            #if DEBUG_COREAUDIO
+            printf("COREAUDIO: Found %s device #%d: '%s' (devid %d)\n",
+                    ((iscapture) ? "capture" : "output"),
+                    (int) *devCount, ptr, (int) dev);
+            #endif
+
+            (*devices)[*devCount].id = dev;
+            (*devices)[*devCount].name = ptr;
+            (*devCount)++;
+        }
     }
-    if ((this == NULL) || (this->hidden == NULL)) {
-        SDL_OutOfMemory();
-        if (this) {
-            SDL_free(this);
-        }
-        return (0);
-    }
-    SDL_memset(this->hidden, 0, (sizeof *this->hidden));
-
-    /* Set the function pointers */
-    this->OpenAudio = Core_OpenAudio;
-    this->WaitAudio = Core_WaitAudio;
-    this->PlayAudio = Core_PlayAudio;
-    this->GetAudioBuf = Core_GetAudioBuf;
-    this->CloseAudio = Core_CloseAudio;
-
-    this->free = Audio_DeleteDevice;
-
-    return this;
 }
 
-AudioBootStrap COREAUDIO_bootstrap = {
-    "coreaudio", "Mac OS X CoreAudio",
-    Audio_Available, Audio_CreateDevice
-};
+static inline void
+build_device_lists(void)
+{
+    build_device_list(0, &outputDevices, &outputDeviceCount);
+    build_device_list(1, &inputDevices, &inputDeviceCount);
+}
+
+
+static inline void
+free_device_lists(void)
+{
+    free_device_list(&outputDevices, &outputDeviceCount);
+    free_device_list(&inputDevices, &inputDeviceCount);
+}
+
+
+static int
+find_device_id(const char *devname, int iscapture, AudioDeviceID *id)
+{
+    int i = ((iscapture) ? inputDeviceCount : outputDeviceCount);
+    COREAUDIO_DeviceList *devs = ((iscapture) ? inputDevices : outputDevices);
+    while (i--) {
+        if (SDL_strcmp(devname, devs->name) == 0) {
+            *id = devs->id;
+            return 1;
+        }
+        devs++;
+    }
+
+    return 0;
+}
+
+
+static int
+COREAUDIO_DetectDevices(int iscapture)
+{
+    if (iscapture) {
+        build_device_list(1, &inputDevices, &inputDeviceCount);
+        return inputDeviceCount;
+    } else {
+        build_device_list(0, &outputDevices, &outputDeviceCount);
+        return outputDeviceCount;
+    }
+
+    return 0;  /* shouldn't ever hit this. */
+}
+
+
+static const char *
+COREAUDIO_GetDeviceName(int index, int iscapture)
+{
+    if ((iscapture) && (index < inputDeviceCount)) {
+        return inputDevices[index].name;
+    } else if ((!iscapture) && (index < outputDeviceCount)) {
+        return outputDevices[index].name;
+    }
+
+    SDL_SetError("No such device");
+    return NULL;
+}
+
+
+static void
+COREAUDIO_Deinitialize(void)
+{
+    free_device_lists();
+}
+
 
 /* The CoreAudio callback */
 static OSStatus
-audioCallback(void *inRefCon,
-              AudioUnitRenderActionFlags inActionFlags,
+outputCallback(void *inRefCon,
+              AudioUnitRenderActionFlags *ioActionFlags,
               const AudioTimeStamp * inTimeStamp,
-              UInt32 inBusNumber, AudioBuffer * ioData)
+              UInt32 inBusNumber, UInt32 inNumberFrames,
+              AudioBufferList *ioDataList)
 {
     SDL_AudioDevice *this = (SDL_AudioDevice *) inRefCon;
+    AudioBuffer *ioData = &ioDataList->mBuffers[0];
     UInt32 remaining, len;
     void *ptr;
 
+    /* Is there ever more than one buffer, and what do you do with it? */
+    if (ioDataList->mNumberBuffers != 1) {
+        return noErr;
+    }
+
     /* Only do anything if audio is enabled and not paused */
     if (!this->enabled || this->paused) {
         SDL_memset(ioData->mData, this->spec.silence, ioData->mDataByteSize);
@@ -118,109 +273,251 @@
     remaining = ioData->mDataByteSize;
     ptr = ioData->mData;
     while (remaining > 0) {
-        if (bufferOffset >= bufferSize) {
+        if (this->hidden->bufferOffset >= this->hidden->bufferSize) {
             /* Generate the data */
-            SDL_memset(buffer, this->spec.silence, bufferSize);
+            SDL_memset(this->hidden->buffer, this->spec.silence,
+                       this->hidden->bufferSize);
             SDL_mutexP(this->mixer_lock);
-            (*this->spec.callback) (this->spec.userdata, buffer, bufferSize);
+            (*this->spec.callback) (this->spec.userdata, this->hidden->buffer,
+                                    this->hidden->bufferSize);
             SDL_mutexV(this->mixer_lock);
-            bufferOffset = 0;
+            this->hidden->bufferOffset = 0;
         }
 
-        len = bufferSize - bufferOffset;
+        len = this->hidden->bufferSize - this->hidden->bufferOffset;
         if (len > remaining)
             len = remaining;
-        SDL_memcpy(ptr, (char *) buffer + bufferOffset, len);
+        SDL_memcpy(ptr,
+                    (char *) this->hidden->buffer + this->hidden->bufferOffset,
+                    len);
         ptr = (char *) ptr + len;
         remaining -= len;
-        bufferOffset += len;
+        this->hidden->bufferOffset += len;
     }
 
     return 0;
 }
 
-/* Dummy functions -- we don't use thread-based audio */
-void
-Core_WaitAudio(_THIS)
+static OSStatus
+inputCallback(void *inRefCon,
+              AudioUnitRenderActionFlags *ioActionFlags,
+              const AudioTimeStamp * inTimeStamp,
+              UInt32 inBusNumber, UInt32 inNumberFrames,
+              AudioBufferList *ioData)
 {
-    return;
-}
-
-void
-Core_PlayAudio(_THIS)
-{
-    return;
-}
-
-Uint8 *
-Core_GetAudioBuf(_THIS)
-{
-    return (NULL);
+    //err = AudioUnitRender(afr->fAudioUnit, ioActionFlags, inTimeStamp, inBusNumber, inNumberFrames, afr->fAudioBuffer);
+    // !!! FIXME: write me!
+    return noErr;
 }
 
-void
-Core_CloseAudio(_THIS)
+
+static void
+COREAUDIO_CloseDevice(_THIS)
 {
-    OSStatus result;
-    struct AudioUnitInputCallback callback;
-
-    /* stop processing the audio unit */
-    result = AudioOutputUnitStop(outputAudioUnit);
-    if (result != noErr) {
-        SDL_SetError("Core_CloseAudio: AudioOutputUnitStop");
-        return;
-    }
+    if (this->hidden != NULL) {
+        OSStatus result = noErr;
+        AURenderCallbackStruct callback;
+        const AudioUnitElement output_bus = 0;
+        const AudioUnitElement input_bus = 1;
+        const int iscapture = this->iscapture;
+        const AudioUnitElement bus = ((iscapture) ? input_bus : output_bus);
+        const AudioUnitScope scope = ((iscapture) ? kAudioUnitScope_Output :
+                                                    kAudioUnitScope_Input);
 
-    /* Remove the input callback */
-    callback.inputProc = 0;
-    callback.inputProcRefCon = 0;
-    result = AudioUnitSetProperty(outputAudioUnit,
-                                  kAudioUnitProperty_SetInputCallback,
-                                  kAudioUnitScope_Input,
-                                  0, &callback, sizeof(callback));
-    if (result != noErr) {
-        SDL_SetError
-            ("Core_CloseAudio: AudioUnitSetProperty (kAudioUnitProperty_SetInputCallback)");
-        return;
+        /* stop processing the audio unit */
+        result = AudioOutputUnitStop(this->hidden->audioUnit);
+
+        /* Remove the input callback */
+        SDL_memset(&callback, '\0', sizeof (AURenderCallbackStruct));
+        result = AudioUnitSetProperty(this->hidden->audioUnit,
+                                      kAudioUnitProperty_SetRenderCallback,
+                                      scope, bus, &callback, sizeof (callback));
+
+        CloseComponent(this->hidden->audioUnit);
+
+        SDL_free(this->hidden->buffer);
+        SDL_free(this->hidden);
+        this->hidden = NULL;
     }
+}
 
-    result = CloseComponent(outputAudioUnit);
-    if (result != noErr) {
-        SDL_SetError("Core_CloseAudio: CloseComponent");
-        return;
-    }
-
-    SDL_free(buffer);
-}
 
 #define CHECK_RESULT(msg) \
     if (result != noErr) { \
+        COREAUDIO_CloseDevice(this); \
         SDL_SetError("CoreAudio error (%s): %d", msg, (int) result); \
-        return -1; \
+        return 0; \
+    }
+
+static int
+find_device_by_name(_THIS, const char *devname, int iscapture)
+{
+    AudioDeviceID devid = 0;
+    OSStatus result = noErr;
+    UInt32 size = 0;
+    UInt32 alive = 0;
+    pid_t pid = 0;
+
+    if (devname == NULL) {
+        size = sizeof (AudioDeviceID);
+        const AudioHardwarePropertyID propid =
+                    ((iscapture) ? kAudioHardwarePropertyDefaultInputDevice :
+                                   kAudioHardwarePropertyDefaultOutputDevice);
+
+        result = AudioHardwareGetProperty(propid, &size, &devid);
+        CHECK_RESULT("AudioHardwareGetProperty (default device)");
+    } else {
+        if (!find_device_id(devname, iscapture, &devid)) {
+            SDL_SetError("CoreAudio: No such audio device.");
+            return 0;
+        }
     }
 
+    size = sizeof (alive);
+    result = AudioDeviceGetProperty(devid, 0, iscapture,
+                                    kAudioDevicePropertyDeviceIsAlive,
+                                    &size, &alive);
+    CHECK_RESULT("AudioDeviceGetProperty (kAudioDevicePropertyDeviceIsAlive)");
 
-int
-Core_OpenAudio(_THIS, SDL_AudioSpec * spec)
+    if (!alive) {
+        SDL_SetError("CoreAudio: requested device exists, but isn't alive.");
+        return 0;
+    }
+
+    size = sizeof (pid);
+    result = AudioDeviceGetProperty(devid, 0, iscapture,
+                                    kAudioDevicePropertyHogMode, &size, &pid);
+
+    /* some devices don't support this property, so errors are fine here. */
+    if ((result == noErr) && (pid != -1)) {
+        SDL_SetError("CoreAudio: requested device is being hogged.");
+        return 0;
+    }
+
+    this->hidden->deviceID = devid;
+    return 1;
+}
+
+
+static int
+prepare_audiounit(_THIS, const char *devname, int iscapture,
+                  const AudioStreamBasicDescription *strdesc)
 {
     OSStatus result = noErr;
-    Component comp;
+    AURenderCallbackStruct callback;
     ComponentDescription desc;
-    struct AudioUnitInputCallback callback;
+    Component comp = NULL;
+    int use_system_device = 0;
+    UInt32 enableIO = 0;
+    const AudioUnitElement output_bus = 0;
+    const AudioUnitElement input_bus = 1;
+    const AudioUnitElement bus = ((iscapture) ? input_bus : output_bus);
+    const AudioUnitScope scope = ((iscapture) ? kAudioUnitScope_Output :
+                                                kAudioUnitScope_Input);
+
+    if (!find_device_by_name(this, devname, iscapture)) {
+        SDL_SetError("Couldn't find requested CoreAudio device");
+        return 0;
+    }
+
+    SDL_memset(&desc, '\0', sizeof(ComponentDescription));
+    desc.componentType = kAudioUnitType_Output;
+    desc.componentSubType = kAudioUnitSubType_HALOutput;
+    desc.componentManufacturer = kAudioUnitManufacturer_Apple;
+
+    comp = FindNextComponent(NULL, &desc);
+    if (comp == NULL) {
+        SDL_SetError("Couldn't find requested CoreAudio component");
+        return 0;
+    }
+
+    /* Open & initialize the audio unit */
+    result = OpenAComponent(comp, &this->hidden->audioUnit);
+    CHECK_RESULT("OpenAComponent");
+
+    // !!! FIXME: this is wrong?
+    enableIO = ((iscapture) ? 1 : 0);
+    result = AudioUnitSetProperty(this->hidden->audioUnit,
+                                  kAudioOutputUnitProperty_EnableIO,
+                                  kAudioUnitScope_Input, input_bus,
+                                  &enableIO, sizeof (enableIO));
+    CHECK_RESULT("AudioUnitSetProperty (kAudioUnitProperty_EnableIO input)");
+
+    // !!! FIXME: this is wrong?
+    enableIO = ((iscapture) ? 0 : 1);
+    result = AudioUnitSetProperty(this->hidden->audioUnit,
+                                  kAudioOutputUnitProperty_EnableIO,
+                                  kAudioUnitScope_Output, output_bus,
+                                  &enableIO, sizeof (enableIO));
+    CHECK_RESULT("AudioUnitSetProperty (kAudioUnitProperty_EnableIO output)");
+
+    result = AudioUnitSetProperty(this->hidden->audioUnit,
+                                  kAudioOutputUnitProperty_CurrentDevice,
+                                  kAudioUnitScope_Global, 0,
+                                  &this->hidden->deviceID,
+                                  sizeof (AudioDeviceID));
+    CHECK_RESULT("AudioUnitSetProperty (kAudioOutputUnitProperty_CurrentDevice)");
+
+    /* Set the data format of the audio unit. */
+    result = AudioUnitSetProperty(this->hidden->audioUnit,
+                                  kAudioUnitProperty_StreamFormat,
+                                  scope, bus, strdesc, sizeof (*strdesc));
+    CHECK_RESULT("AudioUnitSetProperty (kAudioUnitProperty_StreamFormat)");
+
+    /* Set the audio callback */
+    SDL_memset(&callback, '\0', sizeof (AURenderCallbackStruct));
+    callback.inputProc = ((iscapture) ? inputCallback : outputCallback);
+    callback.inputProcRefCon = this;
+    result = AudioUnitSetProperty(this->hidden->audioUnit,
+                                  kAudioUnitProperty_SetRenderCallback,
+                                  scope, bus, &callback, sizeof (callback));
+    CHECK_RESULT("AudioUnitSetProperty (kAudioUnitProperty_SetInputCallback)");
+
+    /* Calculate the final parameters for this audio specification */
+    SDL_CalculateAudioSpec(&this->spec);
+
+    /* Allocate a sample buffer */
+    this->hidden->bufferOffset = this->hidden->bufferSize = this->spec.size;
+    this->hidden->buffer = SDL_malloc(this->hidden->bufferSize);
+
+    result = AudioUnitInitialize(this->hidden->audioUnit);
+    CHECK_RESULT("AudioUnitInitialize");
+
+    /* Finally, start processing of the audio unit */
+    result = AudioOutputUnitStart(this->hidden->audioUnit);
+    CHECK_RESULT("AudioOutputUnitStart");
+
+    /* We're running! */
+    return 1;
+}
+
+
+static int
+COREAUDIO_OpenDevice(_THIS, const char *devname, int iscapture)
+{
     AudioStreamBasicDescription strdesc;
-    SDL_AudioFormat test_format = SDL_FirstAudioFormat(spec->format);
+    SDL_AudioFormat test_format = SDL_FirstAudioFormat(this->spec.format);
     int valid_datatype = 0;
 
+    /* Initialize all variables that we clean on shutdown */
+    this->hidden = (struct SDL_PrivateAudioData *)
+                        SDL_malloc((sizeof *this->hidden));
+    if (this->hidden == NULL) {
+        SDL_OutOfMemory();
+        return (0);
+    }
+    SDL_memset(this->hidden, 0, (sizeof *this->hidden));
+
     /* Setup a AudioStreamBasicDescription with the requested format */
-    memset(&strdesc, '\0', sizeof(AudioStreamBasicDescription));
+    SDL_memset(&strdesc, '\0', sizeof(AudioStreamBasicDescription));
     strdesc.mFormatID = kAudioFormatLinearPCM;
     strdesc.mFormatFlags = kLinearPCMFormatFlagIsPacked;
-    strdesc.mChannelsPerFrame = spec->channels;
-    strdesc.mSampleRate = spec->freq;
+    strdesc.mChannelsPerFrame = this->spec.channels;
+    strdesc.mSampleRate = this->spec.freq;
     strdesc.mFramesPerPacket = 1;
 
     while ((!valid_datatype) && (test_format)) {
-        spec->format = test_format;
+        this->spec.format = test_format;
         /* Just a list of valid SDL formats, so people don't pass junk here. */
         switch (test_format) {
         case AUDIO_U8:
@@ -234,13 +531,13 @@
         case AUDIO_F32LSB:
         case AUDIO_F32MSB:
             valid_datatype = 1;
-            strdesc.mBitsPerChannel = SDL_AUDIO_BITSIZE(spec->format);
-            if (SDL_AUDIO_ISBIGENDIAN(spec->format))
+            strdesc.mBitsPerChannel = SDL_AUDIO_BITSIZE(this->spec.format);
+            if (SDL_AUDIO_ISBIGENDIAN(this->spec.format))
                 strdesc.mFormatFlags |= kLinearPCMFormatFlagIsBigEndian;
 
-            if (SDL_AUDIO_ISFLOAT(spec->format))
+            if (SDL_AUDIO_ISFLOAT(this->spec.format))
                 strdesc.mFormatFlags |= kLinearPCMFormatFlagIsFloat;
-            else if (SDL_AUDIO_ISSIGNED(spec->format))
+            else if (SDL_AUDIO_ISSIGNED(this->spec.format))
                 strdesc.mFormatFlags |= kLinearPCMFormatFlagIsSignedInteger;
             break;
         }
@@ -248,7 +545,7 @@
 
     if (!valid_datatype) {      /* shouldn't happen, but just in case... */
         SDL_SetError("Unsupported audio format");
-        return (-1);
+        return 0;
     }
 
     strdesc.mBytesPerFrame =
@@ -256,52 +553,31 @@
     strdesc.mBytesPerPacket =
         strdesc.mBytesPerFrame * strdesc.mFramesPerPacket;
 
-    /* Locate the default output audio unit */
-    memset(&desc, '\0', sizeof(ComponentDescription));
-    desc.componentType = kAudioUnitComponentType;
-    desc.componentSubType = kAudioUnitSubType_Output;
-    desc.componentManufacturer = kAudioUnitID_DefaultOutput;
-    desc.componentFlags = 0;
-    desc.componentFlagsMask = 0;
-
-    comp = FindNextComponent(NULL, &desc);
-    if (comp == NULL) {
-        SDL_SetError
-            ("Failed to start CoreAudio: FindNextComponent returned NULL");
-        return -1;
+    if (!prepare_audiounit(this, devname, iscapture, &strdesc)) {
+        return 0;  /* prepare_audiounit() will call SDL_SetError()... */
     }
 
-    /* Open & initialize the default output audio unit */
-    result = OpenAComponent(comp, &outputAudioUnit);
-    CHECK_RESULT("OpenAComponent")
-        result = AudioUnitInitialize(outputAudioUnit);
-    CHECK_RESULT("AudioUnitInitialize")
-        /* Set the input format of the audio unit. */
-        result = AudioUnitSetProperty(outputAudioUnit,
-                                      kAudioUnitProperty_StreamFormat,
-                                      kAudioUnitScope_Input,
-                                      0, &strdesc, sizeof(strdesc));
-    CHECK_RESULT("AudioUnitSetProperty (kAudioUnitProperty_StreamFormat)")
-        /* Set the audio callback */
-        callback.inputProc = audioCallback;
-    callback.inputProcRefCon = this;
-    result = AudioUnitSetProperty(outputAudioUnit,
-                                  kAudioUnitProperty_SetInputCallback,
-                                  kAudioUnitScope_Input,
-                                  0, &callback, sizeof(callback));
-    CHECK_RESULT("AudioUnitSetProperty (kAudioUnitProperty_SetInputCallback)")
-        /* Calculate the final parameters for this audio specification */
-        SDL_CalculateAudioSpec(spec);
-
-    /* Allocate a sample buffer */
-    bufferOffset = bufferSize = this->spec.size;
-    buffer = SDL_malloc(bufferSize);
-
-    /* Finally, start processing of the audio unit */
-    result = AudioOutputUnitStart(outputAudioUnit);
-    CHECK_RESULT("AudioOutputUnitStart")
-        /* We're running! */
-        return (1);
+    return 1;  /* good to go. */
 }
 
+static int
+COREAUDIO_Init(SDL_AudioDriverImpl *impl)
+{
+    /* Set the function pointers */
+    impl->DetectDevices = COREAUDIO_DetectDevices;
+    impl->GetDeviceName = COREAUDIO_GetDeviceName;
+    impl->OpenDevice = COREAUDIO_OpenDevice;
+    impl->CloseDevice = COREAUDIO_CloseDevice;
+    impl->Deinitialize = COREAUDIO_Deinitialize;
+    impl->ProvidesOwnCallbackThread = 1;
+
+    build_device_lists();  /* do an initial check for devices... */
+
+    return 1;
+}
+
+AudioBootStrap COREAUDIO_bootstrap = {
+    "coreaudio", "Mac OS X CoreAudio", COREAUDIO_Init, 0
+};
+
 /* vi: set ts=4 sw=4 expandtab: */