pa_win_ds.c

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            unless some flag indicated otherwise */
            
        /* unless alternate device specification is supported, reject the use of
            paUseHostApiSpecificDeviceSpecification */
        if( inputParameters->device == paUseHostApiSpecificDeviceSpecification )
            return paInvalidDevice;

        /* check that input device can support inputChannelCount */
        if( inputChannelCount > hostApi->deviceInfos[ inputParameters->device ]->maxInputChannels )
            return paInvalidChannelCount;
            
        /* validate hostApiSpecificStreamInfo */
        if( inputParameters->hostApiSpecificStreamInfo )
            return paIncompatibleHostApiSpecificStreamInfo; /* this implementation doesn't use custom stream info */
    }
    else
    {
        inputChannelCount = 0;
        suggestedInputLatencyFrames = 0;
    }


    if( outputParameters )
    {
        outputChannelCount = outputParameters->channelCount;
        outputSampleFormat = outputParameters->sampleFormat;
        suggestedOutputLatencyFrames = (unsigned long)(outputParameters->suggestedLatency * sampleRate);

        /* unless alternate device specification is supported, reject the use of
            paUseHostApiSpecificDeviceSpecification */
        if( outputParameters->device == paUseHostApiSpecificDeviceSpecification )
            return paInvalidDevice;

        /* check that output device can support inputChannelCount */
        if( outputChannelCount > hostApi->deviceInfos[ outputParameters->device ]->maxOutputChannels )
            return paInvalidChannelCount;

        /* validate hostApiSpecificStreamInfo */
        if( outputParameters->hostApiSpecificStreamInfo )
            return paIncompatibleHostApiSpecificStreamInfo; /* this implementation doesn't use custom stream info */            
    }
    else
    {
        outputChannelCount = 0;
        suggestedOutputLatencyFrames = 0;
    }


    /*
        IMPLEMENT ME:

        ( the following two checks are taken care of by PaUtil_InitializeBufferProcessor() )

            - check that input device can support inputSampleFormat, or that
                we have the capability to convert from outputSampleFormat to
                a native format

            - check that output device can support outputSampleFormat, or that
                we have the capability to convert from outputSampleFormat to
                a native format

            - if a full duplex stream is requested, check that the combination
                of input and output parameters is supported

            - check that the device supports sampleRate

            - alter sampleRate to a close allowable rate if possible / necessary

            - validate suggestedInputLatency and suggestedOutputLatency parameters,
                use default values where necessary
    */


    /* validate platform specific flags */
    if( (streamFlags & paPlatformSpecificFlags) != 0 )
        return paInvalidFlag; /* unexpected platform specific flag */


    stream = (PaWinDsStream*)PaUtil_AllocateMemory( sizeof(PaWinDsStream) );
    if( !stream )
    {
        result = paInsufficientMemory;
        goto error;
    }

    if( streamCallback )
    {
        PaUtil_InitializeStreamRepresentation( &stream->streamRepresentation,
                                               &winDsHostApi->callbackStreamInterface, streamCallback, userData );
    }
    else
    {
        PaUtil_InitializeStreamRepresentation( &stream->streamRepresentation,
                                               &winDsHostApi->blockingStreamInterface, streamCallback, userData );
    }
    
    PaUtil_InitializeCpuLoadMeasurer( &stream->cpuLoadMeasurer, sampleRate );


    if( inputParameters )
    {
        /* IMPLEMENT ME - establish which  host formats are available */
        hostInputSampleFormat =
            PaUtil_SelectClosestAvailableFormat( paInt16 /* native formats */, inputParameters->sampleFormat );
    }

    if( outputParameters )
    {
        /* IMPLEMENT ME - establish which  host formats are available */
        hostOutputSampleFormat =
            PaUtil_SelectClosestAvailableFormat( paInt16 /* native formats */, outputParameters->sampleFormat );
    }
    
    result =  PaUtil_InitializeBufferProcessor( &stream->bufferProcessor,
                    inputChannelCount, inputSampleFormat, hostInputSampleFormat,
                    outputChannelCount, outputSampleFormat, hostOutputSampleFormat,
                    sampleRate, streamFlags, framesPerBuffer,
                    framesPerBuffer, /* ignored in paUtilVariableHostBufferSizePartialUsageAllowed mode. */
                /* This next mode is required because DS can split the host buffer when it wraps around. */
                    paUtilVariableHostBufferSizePartialUsageAllowed,
                    streamCallback, userData );
    if( result != paNoError )
        goto error;


    stream->streamRepresentation.streamInfo.inputLatency =
            PaUtil_GetBufferProcessorInputLatency(&stream->bufferProcessor);   /* FIXME: not initialised anywhere else */
    stream->streamRepresentation.streamInfo.outputLatency =
            PaUtil_GetBufferProcessorOutputLatency(&stream->bufferProcessor);    /* FIXME: not initialised anywhere else */
    stream->streamRepresentation.streamInfo.sampleRate = sampleRate;

    
/* DirectSound specific initialization */
    {
        HRESULT          hr;
        int              bytesPerDirectSoundBuffer;
        DSoundWrapper   *dsw;
        int              userLatencyFrames;
        int              minLatencyFrames;

        stream->timerID = 0;
        dsw = &stream->directSoundWrapper;
        DSW_Init( dsw );

    /* Get system minimum latency. */
        minLatencyFrames = PaWinDs_GetMinLatencyFrames( sampleRate );

    /* Let user override latency by passing latency parameter. */
        userLatencyFrames = (suggestedInputLatencyFrames > suggestedOutputLatencyFrames)
                    ? suggestedInputLatencyFrames
                    : suggestedOutputLatencyFrames;
        if( userLatencyFrames > 0 ) minLatencyFrames = userLatencyFrames;

    /* Calculate stream->framesPerDSBuffer depending on framesPerBuffer */
        if( framesPerBuffer == paFramesPerBufferUnspecified )
        {
        /* App support variable framesPerBuffer */
            stream->framesPerDSBuffer = minLatencyFrames;

            stream->streamRepresentation.streamInfo.outputLatency = (double)(minLatencyFrames - 1) / sampleRate;
        }
        else
        {
        /* Round up to number of buffers needed to guarantee that latency. */
            int numUserBuffers = (minLatencyFrames + framesPerBuffer - 1) / framesPerBuffer;
            if( numUserBuffers < 1 ) numUserBuffers = 1;
            numUserBuffers += 1; /* So we have latency worth of buffers ahead of current buffer. */
            stream->framesPerDSBuffer = framesPerBuffer * numUserBuffers;

            stream->streamRepresentation.streamInfo.outputLatency = (double)(framesPerBuffer * (numUserBuffers-1)) / sampleRate;
        }

        {
            /** @todo REVIEW: this calculation seems incorrect to me - rossb. */
            int msecLatency = (int) ((stream->framesPerDSBuffer * MSEC_PER_SECOND) / sampleRate);
            PRINT(("PortAudio on DirectSound - Latency = %d frames, %d msec\n", stream->framesPerDSBuffer, msecLatency ));
        }


        /* ------------------ OUTPUT */
        if( outputParameters )
        {
            /*
            PaDeviceInfo *deviceInfo = hostApi->deviceInfos[ outputParameters->device ];
            DBUG(("PaHost_OpenStream: deviceID = 0x%x\n", outputParameters->device));
            */
            
            bytesPerDirectSoundBuffer = stream->framesPerDSBuffer * outputParameters->channelCount * sizeof(short);
            if( bytesPerDirectSoundBuffer < DSBSIZE_MIN )
            {
                result = paBufferTooSmall;
                goto error;
            }
            else if( bytesPerDirectSoundBuffer > DSBSIZE_MAX )
            {
                result = paBufferTooBig;
                goto error;
            }


            hr = dswDSoundEntryPoints.DirectSoundCreate( winDsHostApi->winDsDeviceInfos[outputParameters->device].lpGUID,
                &dsw->dsw_pDirectSound,   NULL );
            if( hr != DS_OK )
            {
                ERR_RPT(("PortAudio: DirectSoundCreate() failed!\n"));
                result = paUnanticipatedHostError;
                PA_DS_SET_LAST_DIRECTSOUND_ERROR( hr );
                goto error;
            }
            hr = DSW_InitOutputBuffer( dsw,
                                       (unsigned long) (sampleRate + 0.5),
                                       (WORD)outputParameters->channelCount, bytesPerDirectSoundBuffer );
            DBUG(("DSW_InitOutputBuffer() returns %x\n", hr));
            if( hr != DS_OK )
            {
                result = paUnanticipatedHostError;
                PA_DS_SET_LAST_DIRECTSOUND_ERROR( hr );
                goto error;
            }
            /* Calculate value used in latency calculation to avoid real-time divides. */
            stream->secondsPerHostByte = 1.0 /
                (stream->bufferProcessor.bytesPerHostOutputSample *
                outputChannelCount * sampleRate);
        }

        /* ------------------ INPUT */
        if( inputParameters )
        {
            /*
            PaDeviceInfo *deviceInfo = hostApi->deviceInfos[ inputParameters->device ];
            DBUG(("PaHost_OpenStream: deviceID = 0x%x\n", inputParameters->device));
            */
            
            bytesPerDirectSoundBuffer = stream->framesPerDSBuffer * inputParameters->channelCount * sizeof(short);
            if( bytesPerDirectSoundBuffer < DSBSIZE_MIN )
            {
                result = paBufferTooSmall;
                goto error;
            }
            else if( bytesPerDirectSoundBuffer > DSBSIZE_MAX )
            {
                result = paBufferTooBig;
                goto error;
            }

            hr = dswDSoundEntryPoints.DirectSoundCaptureCreate( winDsHostApi->winDsDeviceInfos[inputParameters->device].lpGUID,
                &dsw->dsw_pDirectSoundCapture,   NULL );
            if( hr != DS_OK )
            {
                ERR_RPT(("PortAudio: DirectSoundCaptureCreate() failed!\n"));
                result = paUnanticipatedHostError;
                PA_DS_SET_LAST_DIRECTSOUND_ERROR( hr );
                goto error;
            }
            hr = DSW_InitInputBuffer( dsw,
                                      (unsigned long) (sampleRate + 0.5),
                                      (WORD)inputParameters->channelCount, bytesPerDirectSoundBuffer );
            DBUG(("DSW_InitInputBuffer() returns %x\n", hr));
            if( hr != DS_OK )
            {
                ERR_RPT(("PortAudio: DSW_InitInputBuffer() returns %x\n", hr));
                result = paUnanticipatedHostError;
                PA_DS_SET_LAST_DIRECTSOUND_ERROR( hr );
                goto error;
            }
        }

    }

    *s = (PaStream*)stream;

    return result;

error:
    if( stream )
        PaUtil_FreeMemory( stream );

    return result;
}


/***********************************************************************************/
static PaError Pa_TimeSlice( PaWinDsStream *stream )
{
    PaError           result = 0;   /* FIXME: this should be declared int and this function should also return that type (same as stream callback return type)*/
    DSoundWrapper    *dsw;
    long              numFrames = 0;
    long              bytesEmpty = 0;
    long              bytesFilled = 0;
    long              bytesToXfer = 0;
    long              framesToXfer = 0;
    long              numInFramesReady = 0;
    long              numOutFramesReady = 0;
    long              bytesProcessed;
    HRESULT           hresult;
    double            outputLatency = 0;
    PaStreamCallbackTimeInfo timeInfo = {0,0,0}; /** @todo implement inputBufferAdcTime */
    
/* Input */
    LPBYTE            lpInBuf1 = NULL;
    LPBYTE            lpInBuf2 = NULL;
    DWORD             dwInSize1 = 0;
    DWORD             dwInSize2 = 0;
/* Output */
    LPBYTE            lpOutBuf1 = NULL;
    LPBYTE            lpOutBuf2 = NULL;
    DWORD             dwOutSize1 = 0;
    DWORD             dwOutSize2 = 0;

    dsw = &stream->directSoundWrapper;

    /* How much input data is available? */
    if( stream->bufferProcessor.inputChannelCount > 0 )
    {
        DSW_QueryInputFilled( dsw, &bytesFilled );
        framesToXfer = numInFramesReady = bytesFilled / dsw->dsw_BytesPerInputFrame;
        outputLatency = ((double)bytesFilled) * stream->secondsPerHostByte;

        /** @todo Check for overflow */
    }

    /* How much output room is available? */
    if( stream->bufferProcessor.outputChannelCount > 0 )
    {
        UINT previousUnderflowCount = dsw->dsw_OutputUnderflows;
        DSW_QueryOutputSpace( dsw, &bytesEmpty );
        framesToXfer = numOutFramesReady = bytesEmpty / dsw->dsw_BytesPerOutputFrame;

        /* Check for underflow */
        if( dsw->dsw_OutputUnderflows != previousUnderflowCount )
            stream->callbackFlags |= paOutputUnderflow;
    }

    if( (numInFramesReady > 0) && (numOutFramesReady > 0) )
    {
        framesToXfer = (numOutFramesReady < numInFramesReady) ? numOutFramesReady : numInFramesReady;
    }

    if( framesToXfer > 0 )
    {

        PaUtil_BeginCpuLoadMeasurement( &stream->cpuLoadMeasurer );

    /* The outputBufferDacTime parameter should indicates the time at which
        the first sample of the output buffer is heard at the DACs. */
        timeInfo.currentTime = PaUtil_GetTime();
        timeInfo.outputBufferDacTime = timeInfo.currentTime + outputLatency;


        PaUtil_BeginBufferProcessing( &stream->bufferProcessor, &timeInfo, stream->callbackFlags );
        stream->callbackFlags = 0;
        
    /* Input */
        if( stream->bufferProcessor.inputChannelCount > 0 )
        {
            bytesToXfer = framesToXfer * dsw->dsw_BytesPerInputFrame;
            hresult = IDirectSoundCaptureBuffer_Lock ( dsw->dsw_InputBuffer,
                dsw->dsw_ReadOffset, bytesToXfer,
                (void **) &lpInBuf1, &dwInSize1,
                (void **) &lpInBuf2, &dwInSize2, 0);
            if (hresult != DS_OK)