C++ SDL_CalculateAudioSpec函数代码示例

static int DCAUD_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
	switch(spec->format&0xff) {
	case  8: spec->format = AUDIO_S8; break;
	case 16: spec->format = AUDIO_S16LSB; break;
	default:
		SDL_SetError("Unsupported audio format");
		return(-1);
	}

	/* Update the fragment size as size in bytes */
	SDL_CalculateAudioSpec(spec);

	/* Allocate mixing buffer */
	this->hidden->mixlen = spec->size;
	this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
	if ( this->hidden->mixbuf == NULL ) {
		return(-1);
	}
	memset(this->hidden->mixbuf, spec->silence, spec->size);
	this->hidden->leftpos = 0x11000;
	this->hidden->rightpos = 0x11000+spec->size;
	this->hidden->playing = 0;
	this->hidden->nextbuf = 0;

	/* We're ready to rock and roll. :-) */
	return(0);
}

static int Mint_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
	SDL_MintAudio_device = this;

	
	if (Mint_CheckAudio(this, spec)==-1) {
		return -1;
	}

	SDL_CalculateAudioSpec(spec);

	
	DEBUG_PRINT((DEBUG_NAME "buffer size=%d\n", spec->size));

	SDL_MintAudio_audiobuf[0] = Atari_SysMalloc(spec->size *2, MX_STRAM);
	if (SDL_MintAudio_audiobuf[0]==NULL) {
		SDL_SetError("MINT_OpenAudio: Not enough memory for audio buffer");
		return (-1);
	}
	SDL_MintAudio_audiobuf[1] = SDL_MintAudio_audiobuf[0] + spec->size ;
	SDL_MintAudio_numbuf=0;
	SDL_memset(SDL_MintAudio_audiobuf[0], spec->silence, spec->size *2);
	SDL_MintAudio_audiosize = spec->size;
	SDL_MintAudio_mutex = 0;

	DEBUG_PRINT((DEBUG_NAME "buffer 0 at 0x%08x\n", SDL_MintAudio_audiobuf[0]));
	DEBUG_PRINT((DEBUG_NAME "buffer 1 at 0x%08x\n", SDL_MintAudio_audiobuf[1]));

	SDL_MintAudio_CheckFpu();

	
	Mint_InitAudio(this, spec);

    return(1);	
}

static int Mint_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
	SDL_MintAudio_device = this;

	/* Check audio capabilities */
	if (Mint_CheckAudio(this, spec)==-1) {
		return -1;
	}

	SDL_CalculateAudioSpec(spec);

	/* Allocate memory for audio buffers in DMA-able RAM */
	DEBUG_PRINT((DEBUG_NAME "buffer size=%d\n", spec->size));

	SDL_MintAudio_audiobuf[0] = Atari_SysMalloc(spec->size *2, MX_STRAM);
	if (SDL_MintAudio_audiobuf[0]==NULL) {
		SDL_SetError("MINT_OpenAudio: Not enough memory for audio buffer");
		return (-1);
	}
	SDL_MintAudio_audiobuf[1] = SDL_MintAudio_audiobuf[0] + spec->size ;
	SDL_MintAudio_numbuf=0;
	SDL_memset(SDL_MintAudio_audiobuf[0], spec->silence, spec->size *2);
	SDL_MintAudio_audiosize = spec->size;
	SDL_MintAudio_mutex = 0;

	DEBUG_PRINT((DEBUG_NAME "buffer 0 at 0x%08x\n", SDL_MintAudio_audiobuf[0]));
	DEBUG_PRINT((DEBUG_NAME "buffer 1 at 0x%08x\n", SDL_MintAudio_audiobuf[1]));

	SDL_MintAudio_CheckFpu();

	/* Setup audio hardware */
	Mint_InitAudio(this, spec);

    return(1);	/* We don't use threaded audio */
}

static int
AndroidAUD_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
{
    SDL_AudioFormat test_format;

    if (iscapture) {
        /* TODO: implement capture */
        return SDL_SetError("Capture not supported on Android");
    }

    if (audioDevice != NULL) {
        return SDL_SetError("Only one audio device at a time please!");
    }

    audioDevice = this;
    
    this->hidden = (struct SDL_PrivateAudioData *) SDL_calloc(1, (sizeof *this->hidden));
    if (this->hidden == NULL) {
        return SDL_OutOfMemory();
    }

    test_format = SDL_FirstAudioFormat(this->spec.format);
    while (test_format != 0) { /* no "UNKNOWN" constant */
        if ((test_format == AUDIO_U8) || (test_format == AUDIO_S16LSB)) {
            this->spec.format = test_format;
            break;
        }
        test_format = SDL_NextAudioFormat();
    }

    if (test_format == 0) {
        /* Didn't find a compatible format :( */
        return SDL_SetError("No compatible audio format!");
    }

    if (this->spec.channels > 1) {
        this->spec.channels = 2;
    } else {
        this->spec.channels = 1;
    }

    if (this->spec.freq < 8000) {
        this->spec.freq = 8000;
    }
    if (this->spec.freq > 48000) {
        this->spec.freq = 48000;
    }

    /* TODO: pass in/return a (Java) device ID, also whether we're opening for input or output */
    this->spec.samples = Android_JNI_OpenAudioDevice(this->spec.freq, this->spec.format == AUDIO_U8 ? 0 : 1, this->spec.channels, this->spec.samples);
    SDL_CalculateAudioSpec(&this->spec);

    if (this->spec.samples == 0) {
        /* Init failed? */
        return SDL_SetError("Java-side initialization failed!");
    }

    return 0;
}

static int
ANDROIDAUDIO_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
{
    SDL_AudioFormat test_format;

    SDL_assert((captureDevice == NULL) || !iscapture);
    SDL_assert((audioDevice == NULL) || iscapture);

    if (iscapture) {
        captureDevice = this;
    } else {
        audioDevice = this;
    }

    this->hidden = (struct SDL_PrivateAudioData *) SDL_calloc(1, (sizeof *this->hidden));
    if (this->hidden == NULL) {
        return SDL_OutOfMemory();
    }

    test_format = SDL_FirstAudioFormat(this->spec.format);
    while (test_format != 0) { /* no "UNKNOWN" constant */
        if ((test_format == AUDIO_U8) || (test_format == AUDIO_S16LSB)) {
            this->spec.format = test_format;
            break;
        }
        test_format = SDL_NextAudioFormat();
    }

    if (test_format == 0) {
        /* Didn't find a compatible format :( */
        return SDL_SetError("No compatible audio format!");
    }

    if (this->spec.channels > 1) {
        this->spec.channels = 2;
    } else {
        this->spec.channels = 1;
    }

    if (this->spec.freq < 8000) {
        this->spec.freq = 8000;
    }
    if (this->spec.freq > 48000) {
        this->spec.freq = 48000;
    }

    /* TODO: pass in/return a (Java) device ID */
    this->spec.samples = Android_JNI_OpenAudioDevice(iscapture, this->spec.freq, this->spec.format == AUDIO_U8 ? 0 : 1, this->spec.channels, this->spec.samples);

    if (this->spec.samples == 0) {
        /* Init failed? */
        return SDL_SetError("Java-side initialization failed!");
    }

    SDL_CalculateAudioSpec(&this->spec);

    return 0;
}

static int DMA_ReopenAudio(_THIS, const char *audiodev, int format, int stereo,
							SDL_AudioSpec *spec)
{
	int frag_spec;
	int value;

	/* Close and then reopen the audio device */
	close(audio_fd);
	audio_fd = open(audiodev, O_RDWR, 0);
	if ( audio_fd < 0 ) {
		SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
		return(-1);
	}

	/* Calculate the final parameters for this audio specification */
	SDL_CalculateAudioSpec(spec);

	/* Determine the power of two of the fragment size */
	for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
	if ( (0x01<<frag_spec) != spec->size ) {
		SDL_SetError("Fragment size must be a power of two");
		return(-1);
	}

	/* Set the audio buffering parameters */
	if ( ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0 ) {
		SDL_SetError("Couldn't set audio fragment spec");
		return(-1);
	}

	/* Set the audio format */
	value = format;
	if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
						(value != format) ) {
		SDL_SetError("Couldn't set audio format");
		return(-1);
	}

	/* Set mono or stereo audio */
	value = (spec->channels > 1);
	if ( (ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo) < 0) ||
						(value != stereo) ) {
		SDL_SetError("Couldn't set audio channels");
		return(-1);
	}

	/* Set the DSP frequency */
	value = spec->freq;
	if ( ioctl(audio_fd, SNDCTL_DSP_SPEED, &value) < 0 ) {
		SDL_SetError("Couldn't set audio frequency");
		return(-1);
	}
	spec->freq = value;

	/* We successfully re-opened the audio */
	return(0);
}

static int
PSPAUDIO_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
{
    int format, mixlen, i;
    this->hidden = (struct SDL_PrivateAudioData *)
        SDL_malloc(sizeof(*this->hidden));
    if (this->hidden == NULL) {
        return SDL_OutOfMemory();
    }
    SDL_zerop(this->hidden);
    switch (this->spec.format & 0xff) {
        case 8:
        case 16:
            this->spec.format = AUDIO_S16LSB;
            break;
        default:
            return SDL_SetError("Unsupported audio format");
    }

    /* The sample count must be a multiple of 64. */
    this->spec.samples = PSP_AUDIO_SAMPLE_ALIGN(this->spec.samples);
    this->spec.freq = 44100;

    /* Update the fragment size as size in bytes. */
    SDL_CalculateAudioSpec(&this->spec);

    /* Allocate the mixing buffer.  Its size and starting address must
       be a multiple of 64 bytes.  Our sample count is already a multiple of
       64, so spec->size should be a multiple of 64 as well. */
    mixlen = this->spec.size * NUM_BUFFERS;
    this->hidden->rawbuf = (Uint8 *) memalign(64, mixlen);
    if (this->hidden->rawbuf == NULL) {
        return SDL_SetError("Couldn't allocate mixing buffer");
    }

    /* Setup the hardware channel. */
    if (this->spec.channels == 1) {
        format = PSP_AUDIO_FORMAT_MONO;
    } else {
        format = PSP_AUDIO_FORMAT_STEREO;
    }
    this->hidden->channel = sceAudioChReserve(PSP_AUDIO_NEXT_CHANNEL, this->spec.samples, format);
    if (this->hidden->channel < 0) {
        free(this->hidden->rawbuf);
        this->hidden->rawbuf = NULL;
        return SDL_SetError("Couldn't reserve hardware channel");
    }

    memset(this->hidden->rawbuf, 0, mixlen);
    for (i = 0; i < NUM_BUFFERS; i++) {
        this->hidden->mixbufs[i] = &this->hidden->rawbuf[i * this->spec.size];
    }

    this->hidden->next_buffer = 0;
    return 0;
}

static int
MINTSTFA_OpenDevice(_THIS, const char *devname, int iscapture)
{
    SDL_MintAudio_device = this;

    /* Check audio capabilities */
    if (MINTSTFA_CheckAudio(this) == -1) {
        return 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));

    SDL_CalculateAudioSpec(&this->spec);

    /* Allocate memory for audio buffers in DMA-able RAM */
    DEBUG_PRINT((DEBUG_NAME "buffer size=%d\n", this->spec.size));

    SDL_MintAudio_audiobuf[0] =
        Atari_SysMalloc(this->spec.size * 2, MX_STRAM);
    if (SDL_MintAudio_audiobuf[0] == NULL) {
        SDL_OutOfMemory();
        SDL_free(this->hidden);
        this->hidden = NULL;
        return 0;
    }
    SDL_MintAudio_audiobuf[1] = SDL_MintAudio_audiobuf[0] + this->spec.size;
    SDL_MintAudio_numbuf = 0;
    SDL_memset(SDL_MintAudio_audiobuf[0], this->spec.silence,
               this->spec.size * 2);
    SDL_MintAudio_audiosize = this->spec.size;
    SDL_MintAudio_mutex = 0;

    DEBUG_PRINT((DEBUG_NAME "buffer 0 at 0x%08x\n",
                 SDL_MintAudio_audiobuf[0]));
    DEBUG_PRINT((DEBUG_NAME "buffer 1 at 0x%08x\n",
                 SDL_MintAudio_audiobuf[1]));

    SDL_MintAudio_CheckFpu();

    /* Setup audio hardware */
    MINTSTFA_InitAudio(this);

    return 1;                   /* good to go. */
}

static int ANDROIDAUD_OpenAudio(_THIS, const char *devname, int iscapture)
{
	SDL_AudioSpec *audioFormat = &this->spec;
	int bytesPerSample;
	JNIEnv * jniEnv = NULL;

	this->hidden = (struct SDL_PrivateAudioData *) SDL_malloc((sizeof *this->hidden));
	if ( this->hidden == NULL ) {
		SDL_OutOfMemory();
		return(-1);
	}
	SDL_memset(this->hidden, 0, (sizeof *this->hidden));

	if( ! (this->spec.format == AUDIO_S8 || this->spec.format == AUDIO_S16) )
	{
		__android_log_print(ANDROID_LOG_ERROR, "libSDL", "Application requested unsupported audio format - only S8 and S16 are supported");
		return (-1); // TODO: enable format conversion? Don't know how to do that in SDL
	}

	bytesPerSample = (audioFormat->format & 0xFF) / 8;
	audioFormat->format = ( bytesPerSample == 2 ) ? AUDIO_S16 : AUDIO_S8;
	
	(*jniVM)->AttachCurrentThread(jniVM, &jniEnv, NULL);

	if( !jniEnv )
	{
		__android_log_print(ANDROID_LOG_ERROR, "libSDL", "ANDROIDAUD_OpenAudio: Java VM AttachCurrentThread() failed");
		return (-1); // TODO: enable format conversion? Don't know how to do that in SDL
	}

	audioBufferSize = (*jniEnv)->CallIntMethod( jniEnv, JavaAudioThread, JavaInitAudio, 
					(jint)audioFormat->freq, (jint)audioFormat->channels, 
					(jint)(( bytesPerSample == 2 ) ? 1 : 0), (jint)audioFormat->size);

	if( audioBufferSize == 0 )
	{
		__android_log_print(ANDROID_LOG_INFO, "libSDL", "ANDROIDAUD_OpenAudio(): failed to get audio buffer from JNI");
		ANDROIDAUD_CloseAudio(this);
		return(-1);
	}

	/* We cannot call DetachCurrentThread() from main thread or we'll crash */
	/* (*jniVM)->DetachCurrentThread(jniVM); */

	audioFormat->samples = audioBufferSize / bytesPerSample / audioFormat->channels;
	audioFormat->size = audioBufferSize;

	SDL_CalculateAudioSpec(&this->spec);
	
	return(1);
}

static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec)
{

	sDevice = this;

	float bytes_per_sec = 0.0f;

	/*
	/* Allocate mixing buffer */
	//this->hidden->mixlen = spec->size;
	//this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
	//if ( this->hidden->mixbuf == NULL ) {
	//	return(-1);
	//}
	//SDL_memset(this->hidden->mixbuf, spec->silence, spec->size);

	//bytes_per_sec = (float) (((spec->format & 0xFF) / 8) * spec->channels * spec->freq);

	/*
	 * We try to make this request more audio at the correct rate for
	 *  a given audio spec, so timing stays fairly faithful.
	 * Also, we have it not block at all for the first two calls, so
	 *  it seems like we're filling two audio fragments right out of the
	 *  gate, like other SDL drivers tend to do.
	 */
	//this->hidden->initial_calls = 2;
	//this->hidden->write_delay = (Uint32) ((((float) spec->size) / bytes_per_sec) * 1000.0f);


	int bps = 2;
	switch(spec->format) {
		case AUDIO_U8: this->hidden->info.fmt = AUDIO_FMT_U8; bps=1; break;
		case AUDIO_S8: this->hidden->info.fmt = AUDIO_FMT_S8; bps=1; break;
		case AUDIO_U16: this->hidden->info.fmt = AUDIO_FMT_U16; break;
		case AUDIO_S16: this->hidden->info.fmt = AUDIO_FMT_S16; break;
		default: spec->format = AUDIO_S16; this->hidden->info.fmt = AUDIO_FMT_S16; break;
	}

	if(spec->channels>2) spec->channels=2;

	SDL_CalculateAudioSpec(spec);

	this->hidden->info.numChannels = spec->channels;
	this->hidden->info.sampleRate = spec->freq;
	this->hidden->info.bufferSize = spec->samples*bps*spec->channels;
	this->hidden->info.buffer = malloc(this->hidden->info.bufferSize);
	maAudioBufferInit(&this->hidden->info);

	/* We're ready to rock and roll. :-) */
	return (1);
}

static int
ANDROIDAUDIO_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
{
    SDL_AudioFormat test_format;

    SDL_assert((captureDevice == NULL) || !iscapture);
    SDL_assert((audioDevice == NULL) || iscapture);

    if (iscapture) {
        captureDevice = this;
    } else {
        audioDevice = this;
    }

    this->hidden = (struct SDL_PrivateAudioData *) SDL_calloc(1, (sizeof *this->hidden));
    if (this->hidden == NULL) {
        return SDL_OutOfMemory();
    }

    test_format = SDL_FirstAudioFormat(this->spec.format);
    while (test_format != 0) { /* no "UNKNOWN" constant */
        if ((test_format == AUDIO_U8) ||
			(test_format == AUDIO_S16) ||
			(test_format == AUDIO_F32)) {
            this->spec.format = test_format;
            break;
        }
        test_format = SDL_NextAudioFormat();
    }

    if (test_format == 0) {
        /* Didn't find a compatible format :( */
        return SDL_SetError("No compatible audio format!");
    }

    if (Android_JNI_OpenAudioDevice(iscapture, &this->spec) < 0) {
        return -1;
    }

    SDL_CalculateAudioSpec(&this->spec);

    return 0;
}

static int NAS_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
	AuElement elms[3];
	int buffer_size;
	Uint16 test_format, format;

	this->hidden->mixbuf = NULL;

	/* Try for a closest match on audio format */
	format = 0;
	for ( test_format = SDL_FirstAudioFormat(spec->format);
						! format && test_format; ) {
		format = sdlformat_to_auformat(test_format);

		if (format == AuNone) {
			test_format = SDL_NextAudioFormat();
		}
	}
	if ( format == 0 ) {
		SDL_SetError("Couldn't find any hardware audio formats");
		return(-1);
	}
	spec->format = test_format;

	this->hidden->aud = AuOpenServer("", 0, NULL, 0, NULL, NULL);
	if (this->hidden->aud == 0)
	{
		SDL_SetError("Couldn't open connection to NAS server");
		return (-1);
	}
	
	this->hidden->dev = find_device(this, spec->channels);
	if ((this->hidden->dev == AuNone) || (!(this->hidden->flow = AuCreateFlow(this->hidden->aud, NULL)))) {
		AuCloseServer(this->hidden->aud);
		this->hidden->aud = 0;
		SDL_SetError("Couldn't find a fitting playback device on NAS server");
		return (-1);
	}
	
	buffer_size = spec->freq;
	if (buffer_size < 4096)
		buffer_size = 4096; 

	if (buffer_size > 32768)
		buffer_size = 32768; /* So that the buffer won't get unmanageably big. */

	/* Calculate the final parameters for this audio specification */
	SDL_CalculateAudioSpec(spec);

	this2 = this->hidden;

	AuMakeElementImportClient(elms, spec->freq, format, spec->channels, AuTrue,
				buffer_size, buffer_size / 4, 0, NULL);
	AuMakeElementExportDevice(elms+1, 0, this->hidden->dev, spec->freq,
				AuUnlimitedSamples, 0, NULL);
	AuSetElements(this->hidden->aud, this->hidden->flow, AuTrue, 2, elms, NULL);
	AuRegisterEventHandler(this->hidden->aud, AuEventHandlerIDMask, 0, this->hidden->flow,
				event_handler, (AuPointer) NULL);

	AuStartFlow(this->hidden->aud, this->hidden->flow, NULL);

	/* Allocate mixing buffer */
	this->hidden->mixlen = spec->size;
	this->hidden->mixbuf = (Uint8 *)SDL_AllocAudioMem(this->hidden->mixlen);
	if ( this->hidden->mixbuf == NULL ) {
		return(-1);
	}
	memset(this->hidden->mixbuf, spec->silence, spec->size);

	/* Get the parent process id (we're the parent of the audio thread) */
	this->hidden->parent = getpid();

	/* We're ready to rock and roll. :-) */
	return(0);
}

static int
BSDAUDIO_OpenDevice(_THIS, const char *devname, int iscapture)
{
    const int flags = ((iscapture) ? OPEN_FLAGS_INPUT : OPEN_FLAGS_OUTPUT);
    SDL_AudioFormat format = 0;
    audio_info_t info;

    /* We don't care what the devname is...we'll try to open anything. */
    /*  ...but default to first name in the list... */
    if (devname == NULL) {
        devname = SDL_GetAudioDeviceName(0, iscapture);
        if (devname == NULL) {
            SDL_SetError("No such audio device");
            return 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));

    /* Open the audio device */
    this->hidden->audio_fd = open(devname, flags, 0);
    if (this->hidden->audio_fd < 0) {
        SDL_SetError("Couldn't open %s: %s", devname, strerror(errno));
        return 0;
    }

    AUDIO_INITINFO(&info);

    /* Calculate the final parameters for this audio specification */
    SDL_CalculateAudioSpec(&this->spec);

    /* Set to play mode */
    info.mode = AUMODE_PLAY;
    if (ioctl(this->hidden->audio_fd, AUDIO_SETINFO, &info) < 0) {
        BSDAUDIO_CloseDevice(this);
        SDL_SetError("Couldn't put device into play mode");
        return 0;
    }

    AUDIO_INITINFO(&info);
    for (format = SDL_FirstAudioFormat(this->spec.format);
         format; format = SDL_NextAudioFormat()) {
        switch (format) {
        case AUDIO_U8:
            info.play.encoding = AUDIO_ENCODING_ULINEAR;
            info.play.precision = 8;
            break;
        case AUDIO_S8:
            info.play.encoding = AUDIO_ENCODING_SLINEAR;
            info.play.precision = 8;
            break;
        case AUDIO_S16LSB:
            info.play.encoding = AUDIO_ENCODING_SLINEAR_LE;
            info.play.precision = 16;
            break;
        case AUDIO_S16MSB:
            info.play.encoding = AUDIO_ENCODING_SLINEAR_BE;
            info.play.precision = 16;
            break;
        case AUDIO_U16LSB:
            info.play.encoding = AUDIO_ENCODING_ULINEAR_LE;
            info.play.precision = 16;
            break;
        case AUDIO_U16MSB:
            info.play.encoding = AUDIO_ENCODING_ULINEAR_BE;
            info.play.precision = 16;
            break;
        default:
            continue;
        }

        if (ioctl(this->hidden->audio_fd, AUDIO_SETINFO, &info) == 0) {
            break;
        }
    }

    if (!format) {
        BSDAUDIO_CloseDevice(this);
        SDL_SetError("No supported encoding for 0x%x", this->spec.format);
        return 0;
    }

    this->spec.format = format;

    AUDIO_INITINFO(&info);
    info.play.channels = this->spec.channels;
    if (ioctl(this->hidden->audio_fd, AUDIO_SETINFO, &info) == -1) {
        this->spec.channels = 1;
    }
    AUDIO_INITINFO(&info);
    info.play.sample_rate = this->spec.freq;
    info.blocksize = this->spec.size;
    info.hiwat = 5;
//.........这里部分代码省略.........

static int
WINMM_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
{
    SDL_AudioFormat test_format = SDL_FirstAudioFormat(this->spec.format);
    int valid_datatype = 0;
    MMRESULT result;
    WAVEFORMATEX waveformat;
    UINT devId = WAVE_MAPPER;  /* WAVE_MAPPER == choose system's default */
    UINT i;

    if (handle != NULL) {  /* specific device requested? */
        /* -1 because we increment the original value to avoid NULL. */
        const size_t val = ((size_t) handle) - 1;
        devId = (UINT) val;
    }

    /* 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));

    /* Initialize the wavebuf structures for closing */
    for (i = 0; i < NUM_BUFFERS; ++i)
        this->hidden->wavebuf[i].dwUser = 0xFFFF;

    if (this->spec.channels > 2)
        this->spec.channels = 2;        /* !!! FIXME: is this right? */

    while ((!valid_datatype) && (test_format)) {
        switch (test_format) {
        case AUDIO_U8:
        case AUDIO_S16:
        case AUDIO_S32:
        case AUDIO_F32:
            this->spec.format = test_format;
            if (PrepWaveFormat(this, devId, &waveformat, iscapture)) {
                valid_datatype = 1;
            } else {
                test_format = SDL_NextAudioFormat();
            }
            break;

        default:
            test_format = SDL_NextAudioFormat();
            break;
        }
    }

    if (!valid_datatype) {
        WINMM_CloseDevice(this);
        return SDL_SetError("Unsupported audio format");
    }

    /* Update the fragment size as size in bytes */
    SDL_CalculateAudioSpec(&this->spec);

    /* Open the audio device */
    if (iscapture) {
        result = waveInOpen(&this->hidden->hin, devId, &waveformat,
                             (DWORD_PTR) CaptureSound, (DWORD_PTR) this,
                             CALLBACK_FUNCTION);
    } else {
        result = waveOutOpen(&this->hidden->hout, devId, &waveformat,
                             (DWORD_PTR) FillSound, (DWORD_PTR) this,
                             CALLBACK_FUNCTION);
    }

    if (result != MMSYSERR_NOERROR) {
        WINMM_CloseDevice(this);
        return SetMMerror("waveOutOpen()", result);
    }
#ifdef SOUND_DEBUG
    /* Check the sound device we retrieved */
    {
        WAVEOUTCAPS caps;

        result = waveOutGetDevCaps((UINT) this->hidden->hout,
                                   &caps, sizeof(caps));
        if (result != MMSYSERR_NOERROR) {
            WINMM_CloseDevice(this);
            return SetMMerror("waveOutGetDevCaps()", result);
        }
        printf("Audio device: %s\n", caps.szPname);
    }
#endif

    /* Create the audio buffer semaphore */
    this->hidden->audio_sem =
        CreateSemaphore(NULL, NUM_BUFFERS - 1, NUM_BUFFERS, NULL);
    if (this->hidden->audio_sem == NULL) {
        WINMM_CloseDevice(this);
        return SDL_SetError("Couldn't create semaphore");
    }

    /* Create the sound buffers */
    this->hidden->mixbuf =
        (Uint8 *) SDL_malloc(NUM_BUFFERS * this->spec.size);
//.........这里部分代码省略.........

static int
XAUDIO2_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
{
    HRESULT result = S_OK;
    WAVEFORMATEX waveformat;
    int valid_format = 0;
    SDL_AudioFormat test_format = SDL_FirstAudioFormat(this->spec.format);
    IXAudio2 *ixa2 = NULL;
    IXAudio2SourceVoice *source = NULL;
#if defined(SDL_XAUDIO2_WIN8)
    LPCWSTR devId = NULL;
#else
    UINT32 devId = 0;  /* 0 == system default device. */
#endif

    static IXAudio2VoiceCallbackVtbl callbacks_vtable = {
        VoiceCBOnVoiceProcessPassStart,
        VoiceCBOnVoiceProcessPassEnd,
        VoiceCBOnStreamEnd,
        VoiceCBOnBufferStart,
        VoiceCBOnBufferEnd,
        VoiceCBOnLoopEnd,
        VoiceCBOnVoiceError
    };

    static IXAudio2VoiceCallback callbacks = { &callbacks_vtable };

#if defined(SDL_XAUDIO2_WIN8)
    /* !!! FIXME: hook up hotplugging. */
#else
    if (handle != NULL) {  /* specific device requested? */
        /* -1 because we increment the original value to avoid NULL. */
        const size_t val = ((size_t) handle) - 1;
        devId = (UINT32) val;
    }
#endif

    if (XAudio2Create(&ixa2, 0, XAUDIO2_DEFAULT_PROCESSOR) != S_OK) {
        return SDL_SetError("XAudio2: XAudio2Create() failed at open.");
    }

    /*
    XAUDIO2_DEBUG_CONFIGURATION debugConfig;
    debugConfig.TraceMask = XAUDIO2_LOG_ERRORS; //XAUDIO2_LOG_WARNINGS | XAUDIO2_LOG_DETAIL | XAUDIO2_LOG_FUNC_CALLS | XAUDIO2_LOG_TIMING | XAUDIO2_LOG_LOCKS | XAUDIO2_LOG_MEMORY | XAUDIO2_LOG_STREAMING;
    debugConfig.BreakMask = XAUDIO2_LOG_ERRORS; //XAUDIO2_LOG_WARNINGS;
    debugConfig.LogThreadID = TRUE;
    debugConfig.LogFileline = TRUE;
    debugConfig.LogFunctionName = TRUE;
    debugConfig.LogTiming = TRUE;
    ixa2->SetDebugConfiguration(&debugConfig);
    */

    /* Initialize all variables that we clean on shutdown */
    this->hidden = (struct SDL_PrivateAudioData *)
        SDL_malloc((sizeof *this->hidden));
    if (this->hidden == NULL) {
        IXAudio2_Release(ixa2);
        return SDL_OutOfMemory();
    }
    SDL_memset(this->hidden, 0, (sizeof *this->hidden));

    this->hidden->ixa2 = ixa2;
    this->hidden->semaphore = SDL_CreateSemaphore(1);
    if (this->hidden->semaphore == NULL) {
        XAUDIO2_CloseDevice(this);
        return SDL_SetError("XAudio2: CreateSemaphore() failed!");
    }

    while ((!valid_format) && (test_format)) {
        switch (test_format) {
        case AUDIO_U8:
        case AUDIO_S16:
        case AUDIO_S32:
        case AUDIO_F32:
            this->spec.format = test_format;
            valid_format = 1;
            break;
        }
        test_format = SDL_NextAudioFormat();
    }

    if (!valid_format) {
        XAUDIO2_CloseDevice(this);
        return SDL_SetError("XAudio2: Unsupported audio format");
    }

    /* Update the fragment size as size in bytes */
    SDL_CalculateAudioSpec(&this->spec);

    /* We feed a Source, it feeds the Mastering, which feeds the device. */
    this->hidden->mixlen = this->spec.size;
    this->hidden->mixbuf = (Uint8 *) SDL_malloc(2 * this->hidden->mixlen);
    if (this->hidden->mixbuf == NULL) {
        XAUDIO2_CloseDevice(this);
        return SDL_OutOfMemory();
    }
    this->hidden->nextbuf = this->hidden->mixbuf;
    SDL_memset(this->hidden->mixbuf, 0, 2 * this->hidden->mixlen);

    /* We use XAUDIO2_DEFAULT_CHANNELS instead of this->spec.channels. On
//.........这里部分代码省略.........