src/audio/coreaudio/SDL_coreaudio.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_config.h"
#include "SDL_audio.h"
#include "../SDL_audio_c.h"
#include "../SDL_sysaudio.h"
#include "SDL_coreaudio.h"
#include "SDL_assert.h"

#define DEBUG_COREAUDIO 0

static void COREAUDIO_CloseDevice(_THIS);

#define CHECK_RESULT(msg) \
    if (result != noErr) { \
        COREAUDIO_CloseDevice(this); \
        SDL_SetError("CoreAudio error (%s): %d", msg, (int) result); \
        return 0; \
    }

#if MACOSX_COREAUDIO
typedef void (*addDevFn)(const char *name, AudioDeviceID devId, void *data);

static void
addToDevList(const char *name, AudioDeviceID devId, void *data)
{
    SDL_AddAudioDevice addfn = (SDL_AddAudioDevice) data;
    addfn(name);
}

typedef struct
{
    const char *findname;
    AudioDeviceID devId;
    int found;
} FindDevIdData;

static void
findDevId(const char *name, AudioDeviceID devId, void *_data)
{
    FindDevIdData *data = (FindDevIdData *) _data;
    if (!data->found) {
        if (SDL_strcmp(name, data->findname) == 0) {
            data->found = 1;
            data->devId = devId;
        }
    }
}

static void
build_device_list(int iscapture, addDevFn addfn, void *addfndata)
{
    OSStatus result = noErr;
    UInt32 size = 0;
    AudioDeviceID *devs = NULL;
    UInt32 i = 0;
    UInt32 max = 0;

    AudioObjectPropertyAddress addr = {
        kAudioHardwarePropertyDevices,
        kAudioObjectPropertyScopeGlobal,
        kAudioObjectPropertyElementMaster
    };

    result = AudioObjectGetPropertyDataSize(kAudioObjectSystemObject, &addr,
                                            0, NULL, &size);
    if (result != kAudioHardwareNoError)
        return;

    devs = (AudioDeviceID *) alloca(size);
    if (devs == NULL)
        return;

    result = AudioObjectGetPropertyData(kAudioObjectSystemObject, &addr,
                                        0, NULL, &size, devs);
    if (result != kAudioHardwareNoError)
        return;

    max = size / sizeof (AudioDeviceID);
    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;

        addr.mScope = iscapture ? kAudioDevicePropertyScopeInput :
                        kAudioDevicePropertyScopeOutput;
        addr.mSelector = kAudioDevicePropertyStreamConfiguration;

        result = AudioObjectGetPropertyDataSize(dev, &addr, 0, NULL, &size);
        if (result != noErr)
            continue;

        buflist = (AudioBufferList *) SDL_malloc(size);
        if (buflist == NULL)
            continue;

        result = AudioObjectGetPropertyData(dev, &addr, 0, NULL,
                                            &size, buflist);

        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;

        addr.mSelector = kAudioObjectPropertyName;
        size = sizeof (CFStringRef);
        result = AudioObjectGetPropertyData(dev, &addr, 0, NULL, &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) {
            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
            addfn(ptr, dev, addfndata);
        }
        SDL_free(ptr);  /* addfn() would have copied the string. */
    }
}

static void
COREAUDIO_DetectDevices(int iscapture, SDL_AddAudioDevice addfn)
{
    build_device_list(iscapture, addToDevList, addfn);
}

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;

    AudioObjectPropertyAddress addr = {
        0,
        kAudioObjectPropertyScopeGlobal,
        kAudioObjectPropertyElementMaster
    };

    if (devname == NULL) {
        size = sizeof (AudioDeviceID);
        addr.mSelector =
            ((iscapture) ? kAudioHardwarePropertyDefaultInputDevice :
            kAudioHardwarePropertyDefaultOutputDevice);
        result = AudioObjectGetPropertyData(kAudioObjectSystemObject, &addr,
                                            0, NULL, &size, &devid);
        CHECK_RESULT("AudioHardwareGetProperty (default device)");
    } else {
        FindDevIdData data;
        SDL_zero(data);
        data.findname = devname;
        build_device_list(iscapture, findDevId, &data);
        if (!data.found) {
            SDL_SetError("CoreAudio: No such audio device.");
            return 0;
        }
        devid = data.devId;
    }

    addr.mSelector = kAudioDevicePropertyDeviceIsAlive;
    addr.mScope = iscapture ? kAudioDevicePropertyScopeInput :
                    kAudioDevicePropertyScopeOutput;

    size = sizeof (alive);
    result = AudioObjectGetPropertyData(devid, &addr, 0, NULL, &size, &alive);
    CHECK_RESULT
        ("AudioDeviceGetProperty (kAudioDevicePropertyDeviceIsAlive)");

    if (!alive) {
        SDL_SetError("CoreAudio: requested device exists, but isn't alive.");
        return 0;
    }

    addr.mSelector = kAudioDevicePropertyHogMode;
    size = sizeof (pid);
    result = AudioObjectGetPropertyData(devid, &addr, 0, NULL, &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;
}
#endif

/* The CoreAudio callback */
static OSStatus
outputCallback(void *inRefCon,
               AudioUnitRenderActionFlags * ioActionFlags,
               const AudioTimeStamp * inTimeStamp,
               UInt32 inBusNumber, UInt32 inNumberFrames,
               AudioBufferList * ioData)
{
    SDL_AudioDevice *this = (SDL_AudioDevice *) inRefCon;
    AudioBuffer *abuf;
    UInt32 remaining, len;
    void *ptr;
    UInt32 i;

    /* Only do anything if audio is enabled and not paused */
    if (!this->enabled || this->paused) {
        for (i = 0; i < ioData->mNumberBuffers; i++) {
            abuf = &ioData->mBuffers[i];
            SDL_memset(abuf->mData, this->spec.silence, abuf->mDataByteSize);
        }
        return 0;
    }

    /* No SDL conversion should be needed here, ever, since we accept
       any input format in OpenAudio, and leave the conversion to CoreAudio.
     */
    /*
       SDL_assert(!this->convert.needed);
       SDL_assert(this->spec.channels == ioData->mNumberChannels);
     */

    for (i = 0; i < ioData->mNumberBuffers; i++) {
        abuf = &ioData->mBuffers[i];
        remaining = abuf->mDataByteSize;
        ptr = abuf->mData;
        while (remaining > 0) {
            if (this->hidden->bufferOffset >= this->hidden->bufferSize) {
                /* Generate the data */
                SDL_LockMutex(this->mixer_lock);
                (*this->spec.callback)(this->spec.userdata,
                            this->hidden->buffer, this->hidden->bufferSize);
                SDL_UnlockMutex(this->mixer_lock);
                this->hidden->bufferOffset = 0;
            }

            len = this->hidden->bufferSize - this->hidden->bufferOffset;
            if (len > remaining)
                len = remaining;
            SDL_memcpy(ptr, (char *)this->hidden->buffer +
                       this->hidden->bufferOffset, len);
            ptr = (char *)ptr + len;
            remaining -= len;
            this->hidden->bufferOffset += len;
        }
    }

    return 0;
}

static OSStatus
inputCallback(void *inRefCon,
              AudioUnitRenderActionFlags * ioActionFlags,
              const AudioTimeStamp * inTimeStamp,
              UInt32 inBusNumber, UInt32 inNumberFrames,
              AudioBufferList * ioData)
{
    /* err = AudioUnitRender(afr->fAudioUnit, ioActionFlags, inTimeStamp, inBusNumber, inNumberFrames, afr->fAudioBuffer); */
    /* !!! FIXME: write me! */
    return noErr;
}


static void
COREAUDIO_CloseDevice(_THIS)
{
    if (this->hidden != NULL) {
        if (this->hidden->audioUnitOpened) {
            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);

            /* 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));

            #if MACOSX_COREAUDIO
            CloseComponent(this->hidden->audioUnit);
            #else
            AudioComponentInstanceDispose(this->hidden->audioUnit);
            #endif

            this->hidden->audioUnitOpened = 0;
        }
        SDL_free(this->hidden->buffer);
        SDL_free(this->hidden);
        this->hidden = NULL;
    }
}


static int
prepare_audiounit(_THIS, const char *devname, int iscapture,
                  const AudioStreamBasicDescription * strdesc)
{
    OSStatus result = noErr;
    AURenderCallbackStruct callback;
#if MACOSX_COREAUDIO
    ComponentDescription desc;
    Component comp = NULL;
#else
    AudioComponentDescription desc;
    AudioComponent comp = NULL;
#endif
    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 MACOSX_COREAUDIO
    if (!find_device_by_name(this, devname, iscapture)) {
        SDL_SetError("Couldn't find requested CoreAudio device");
        return 0;
    }
#endif

    SDL_zero(desc);
    desc.componentType = kAudioUnitType_Output;
    desc.componentManufacturer = kAudioUnitManufacturer_Apple;

#if MACOSX_COREAUDIO
    desc.componentSubType = kAudioUnitSubType_DefaultOutput;
    comp = FindNextComponent(NULL, &desc);
#else
    desc.componentSubType = kAudioUnitSubType_RemoteIO;
    comp = AudioComponentFindNext(NULL, &desc);
#endif

    if (comp == NULL) {
        SDL_SetError("Couldn't find requested CoreAudio component");
        return 0;
    }

    /* Open & initialize the audio unit */
#if MACOSX_COREAUDIO
    result = OpenAComponent(comp, &this->hidden->audioUnit);
    CHECK_RESULT("OpenAComponent");
#else
    /*
       AudioComponentInstanceNew only available on iPhone OS 2.0 and Mac OS X 10.6
       We can't use OpenAComponent on iPhone because it is not present
     */
    result = AudioComponentInstanceNew(comp, &this->hidden->audioUnit);
    CHECK_RESULT("AudioComponentInstanceNew");
#endif

    this->hidden->audioUnitOpened = 1;

#if MACOSX_COREAUDIO
    result = AudioUnitSetProperty(this->hidden->audioUnit,
                                  kAudioOutputUnitProperty_CurrentDevice,
                                  kAudioUnitScope_Global, 0,
                                  &this->hidden->deviceID,
                                  sizeof(AudioDeviceID));
    CHECK_RESULT
        ("AudioUnitSetProperty (kAudioOutputUnitProperty_CurrentDevice)");
#endif

    /* 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_SetRenderCallback)");

    /* 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(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) {
        return SDL_OutOfMemory();
    }
    SDL_memset(this->hidden, 0, (sizeof *this->hidden));

    /* Setup a AudioStreamBasicDescription with the requested format */
    SDL_memset(&strdesc, '\0', sizeof(AudioStreamBasicDescription));
    strdesc.mFormatID = kAudioFormatLinearPCM;
    strdesc.mFormatFlags = kLinearPCMFormatFlagIsPacked;
    strdesc.mChannelsPerFrame = this->spec.channels;
    strdesc.mSampleRate = this->spec.freq;
    strdesc.mFramesPerPacket = 1;

    while ((!valid_datatype) && (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:
        case AUDIO_S8:
        case AUDIO_U16LSB:
        case AUDIO_S16LSB:
        case AUDIO_U16MSB:
        case AUDIO_S16MSB:
        case AUDIO_S32LSB:
        case AUDIO_S32MSB:
        case AUDIO_F32LSB:
        case AUDIO_F32MSB:
            valid_datatype = 1;
            strdesc.mBitsPerChannel = SDL_AUDIO_BITSIZE(this->spec.format);
            if (SDL_AUDIO_ISBIGENDIAN(this->spec.format))
                strdesc.mFormatFlags |= kLinearPCMFormatFlagIsBigEndian;

            if (SDL_AUDIO_ISFLOAT(this->spec.format))
                strdesc.mFormatFlags |= kLinearPCMFormatFlagIsFloat;
            else if (SDL_AUDIO_ISSIGNED(this->spec.format))
                strdesc.mFormatFlags |= kLinearPCMFormatFlagIsSignedInteger;
            break;
        }
    }

    if (!valid_datatype) {      /* shouldn't happen, but just in case... */
        COREAUDIO_CloseDevice(this);
        return SDL_SetError("Unsupported audio format");
    }

    strdesc.mBytesPerFrame =
        strdesc.mBitsPerChannel * strdesc.mChannelsPerFrame / 8;
    strdesc.mBytesPerPacket =
        strdesc.mBytesPerFrame * strdesc.mFramesPerPacket;

    if (!prepare_audiounit(this, devname, iscapture, &strdesc)) {
        COREAUDIO_CloseDevice(this);
        return -1;      /* prepare_audiounit() will call SDL_SetError()... */
    }

    return 0;   /* good to go. */
}

static int
COREAUDIO_Init(SDL_AudioDriverImpl * impl)
{
    /* Set the function pointers */
    impl->OpenDevice = COREAUDIO_OpenDevice;
    impl->CloseDevice = COREAUDIO_CloseDevice;

#if MACOSX_COREAUDIO
    impl->DetectDevices = COREAUDIO_DetectDevices;
#else
    impl->OnlyHasDefaultOutputDevice = 1;

    /* Set category to ambient sound so that other music continues playing.
       You can change this at runtime in your own code if you need different
       behavior.  If this is common, we can add an SDL hint for this.
    */
    AudioSessionInitialize(NULL, NULL, NULL, nil);
    UInt32 category = kAudioSessionCategory_AmbientSound;
    AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(UInt32), &category);
#endif

    impl->ProvidesOwnCallbackThread = 1;

    return 1;   /* this audio target is available. */
}

AudioBootStrap COREAUDIO_bootstrap = {
    "coreaudio", "CoreAudio", COREAUDIO_Init, 0
};

/* vi: set ts=4 sw=4 expandtab: */