pa_lib.c

Audacity是一款用於錄音和編輯聲音的、免費的開放源碼軟體。它可以執行於Mac OS X、Microsoft Windows、GNU/Linux和其它作業系統

    past->past_Usage = 0;
    past->past_IfLastExitValid = 0;

    return result;
}

/*************************************************************************/
DLL_API PaError Pa_StreamActive( PortAudioStream *stream )
{
    internalPortAudioStream   *past;
    if( stream == NULL ) return paBadStreamPtr;
    past = (internalPortAudioStream *) stream;
    return PaHost_StreamActive( past );
}

/*************************************************************************/
DLL_API const char *Pa_GetErrorText( PaError errnum )
{
    const char *msg;

    switch(errnum)
    {
    case paNoError:                  msg = "Success"; break;
    case paHostError:                msg = "Host error."; break;
    case paInvalidChannelCount:      msg = "Invalid number of channels."; break;
    case paInvalidSampleRate:        msg = "Invalid sample rate."; break;
    case paInvalidDeviceId:          msg = "Invalid device ID."; break;
    case paInvalidFlag:              msg = "Invalid flag."; break;
    case paSampleFormatNotSupported: msg = "Sample format not supported"; break;
    case paBadIODeviceCombination:   msg = "Illegal combination of I/O devices."; break;
    case paInsufficientMemory:       msg = "Insufficient memory."; break;
    case paBufferTooBig:             msg = "Buffer too big."; break;
    case paBufferTooSmall:           msg = "Buffer too small."; break;
    case paNullCallback:             msg = "No callback routine specified."; break;
    case paBadStreamPtr:             msg = "Invalid stream pointer."; break;
    case paTimedOut    :             msg = "Wait Timed Out."; break;
    case paInternalError:            msg = "Internal PortAudio Error."; break;
    default:                         msg = "Illegal error number."; break;
    }
    return msg;
}

/*
 Get CPU Load as a fraction of total CPU time.
 A value of 0.5 would imply that PortAudio and the sound generating
 callback was consuming roughly 50% of the available CPU time.
 The amount may vary depending on CPU load.
 This function may be called from the callback function.
*/
DLL_API double Pa_GetCPULoad(  PortAudioStream* stream)
{
    internalPortAudioStream   *past;
    if( stream == NULL ) return (double) paBadStreamPtr;
    past = (internalPortAudioStream *) stream;
    return past->past_Usage;
}

/*************************************************************
** Calculate 2 LSB dither signal with a triangular distribution.
** Ranged properly for adding to a 32 bit integer prior to >>15.
*/
#define DITHER_BITS   (15)
#define DITHER_SCALE  (1.0f / ((1<<DITHER_BITS)-1))
static long Pa_TriangularDither( void )
{
    static unsigned long previous = 0;
    static unsigned long randSeed1 = 22222;
    static unsigned long randSeed2 = 5555555;
    long current, highPass;
    /* Generate two random numbers. */
    randSeed1 = (randSeed1 * 196314165) + 907633515;
    randSeed2 = (randSeed2 * 196314165) + 907633515;
    /* Generate triangular distribution about 0. */
    current = (((long)randSeed1)>>(32-DITHER_BITS)) + (((long)randSeed2)>>(32-DITHER_BITS));
    /* High pass filter to reduce audibility. */
    highPass = current - previous;
    previous = current;
    return highPass;
}

/*************************************************************************
** Called by host code.
** Convert input from Int16, call user code, then convert output
** to Int16 format for native use.
** Assumes host native format is paInt16.
** Returns result from user callback.
*/
long Pa_CallConvertInt16( internalPortAudioStream   *past,
                          short *nativeInputBuffer,
                          short *nativeOutputBuffer )
{
    long              temp;
    long              bytesEmpty = 0;
    long              bytesFilled = 0;
    int               userResult;
    unsigned int      i;
    void             *inputBuffer = NULL;
    void             *outputBuffer = NULL;

#if SUPPORT_AUDIO_CAPTURE
    /* Get native data from DirectSound. */
    if( (past->past_NumInputChannels > 0) && (nativeInputBuffer != NULL) )
    {
        /* Convert from native format to PA format. */
        unsigned int samplesPerBuffer = past->past_FramesPerUserBuffer * past->past_NumInputChannels;
        switch(past->past_InputSampleFormat)
        {

        case paFloat32:
            {
                float *inBufPtr = (float *) past->past_InputBuffer;
                inputBuffer = past->past_InputBuffer;
                for( i=0; i<samplesPerBuffer; i++ )
                {
                    inBufPtr[i] = nativeInputBuffer[i] * (1.0f / 32767.0f);
                }
                break;
            }

        case paInt32:
            {
                /* Convert 16 bit data to 32 bit integers */
                int *inBufPtr = (int *) past->past_InputBuffer;
                inputBuffer = past->past_InputBuffer;
                for( i=0; i<samplesPerBuffer; i++ )
                {
                    inBufPtr[i] = nativeInputBuffer[i] << 16;
                }
                break;
            }

        case paInt16:
            {
                /* Already in correct format so don't copy. */
                inputBuffer = nativeInputBuffer;
                break;
            }

        case paInt8:
            {
                /* Convert 16 bit data to 8 bit chars */
                char *inBufPtr = (char *) past->past_InputBuffer;
                inputBuffer = past->past_InputBuffer;
                if( past->past_Flags & paDitherOff )
                {
                    for( i=0; i<samplesPerBuffer; i++ )
                    {
                        inBufPtr[i] = (char)(nativeInputBuffer[i] >> 8);
                    }
                }
                else
                {
                    for( i=0; i<samplesPerBuffer; i++ )
                    {
                        temp = nativeInputBuffer[i];
                        temp += Pa_TriangularDither() >> 7;
                        temp = ((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
                        inBufPtr[i] = (char)(temp >> 8);
                    }
                }
                break;
            }

        case paUInt8:
            {
                /* Convert 16 bit data to 8 bit unsigned chars */
                unsigned char *inBufPtr = (unsigned char *) past->past_InputBuffer;
                inputBuffer = past->past_InputBuffer;
                if( past->past_Flags & paDitherOff )
                {
                    for( i=0; i<samplesPerBuffer; i++ )
                    {
                        inBufPtr[i] = ((unsigned char)(nativeInputBuffer[i] >> 8)) + 0x80;
                    }
                }
                else
                {
                    /* If you dither then you have to clip because dithering could push the signal out of range! */
                    for( i=0; i<samplesPerBuffer; i++ )
                    {
                        temp = nativeInputBuffer[i];
                        temp += Pa_TriangularDither() >> 7;
                        temp = ((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
                        inBufPtr[i] = (unsigned char)(temp + 0x80);
                    }
                }
                break;
            }

        default:
            break;
        }
    }
#endif /* SUPPORT_AUDIO_CAPTURE */

    /* Are we doing output time? */
    if( (past->past_NumOutputChannels > 0) && (nativeOutputBuffer != NULL) )
    {
        /* May already be in native format so just write directly to native buffer. */
        outputBuffer = (past->past_OutputSampleFormat == paInt16) ?
                       nativeOutputBuffer : past->past_OutputBuffer;
    }
    /*
     AddTraceMessage("Pa_CallConvertInt16: inputBuffer = ", (int) inputBuffer );
     AddTraceMessage("Pa_CallConvertInt16: outputBuffer = ", (int) outputBuffer );
    */
    /* Call user callback routine. */
    userResult = past->past_Callback(
                     inputBuffer,
                     outputBuffer,
                     past->past_FramesPerUserBuffer,
                     past->past_FrameCount,
                     past->past_UserData );

    past->past_FrameCount += (PaTimestamp) past->past_FramesPerUserBuffer;

    /* Convert to native format if necessary. */
    if( outputBuffer != NULL )
    {
        unsigned int samplesPerBuffer = past->past_FramesPerUserBuffer * past->past_NumOutputChannels;
        switch(past->past_OutputSampleFormat)
        {
        case paFloat32:
            {
                float *outBufPtr = (float *) past->past_OutputBuffer;
                if( past->past_Flags & paDitherOff )
                {
                    if( past->past_Flags & paClipOff ) /* NOTHING */
                    {
                        for( i=0; i<samplesPerBuffer; i++ )
                        {
                            *nativeOutputBuffer++ = (short) (outBufPtr[i] * (32767.0f));
                        }
                    }
                    else /* CLIP */
                    {
                        for( i=0; i<samplesPerBuffer; i++ )
                        {
                            temp = (long)(outBufPtr[i] * 32767.0f);
                            *nativeOutputBuffer++ = (short)((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
                        }
                    }
                }
                else
                {
                    /* If you dither then you have to clip because dithering could push the signal out of range! */
                    for( i=0; i<samplesPerBuffer; i++ )
                    {
                        float dither  = Pa_TriangularDither()*DITHER_SCALE;
                        float dithered = (outBufPtr[i] * (32767.0f)) + dither;
                        temp = (long) (dithered);
                        *nativeOutputBuffer++ = (short)((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
                    }
                }
                break;
            }

        case paInt32:
            {
                int *outBufPtr = (int *) past->past_OutputBuffer;
                if( past->past_Flags & paDitherOff )
                {
                    for( i=0; i<samplesPerBuffer; i++ )
                    {
                        *nativeOutputBuffer++ = (short) (outBufPtr[i] >> 16 );
                    }
                }
                else
                {
                    for( i=0; i<samplesPerBuffer; i++ )
                    {
                        /* Shift one bit down before dithering so that we have room for overflow from add. */
                        temp = (outBufPtr[i] >> 1) + Pa_TriangularDither();
                        temp = temp >> 15;
                        *nativeOutputBuffer++ = (short)((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
                    }
                }
                break;
            }

        case paInt8:
            {
                char *outBufPtr = (char *) past->past_OutputBuffer;
                for( i=0; i<samplesPerBuffer; i++ )
                {
                    *nativeOutputBuffer++ = ((short)outBufPtr[i]) << 8;
                }
                break;
            }

        case paUInt8:
            {
                unsigned char *outBufPtr = (unsigned char *) past->past_OutputBuffer;
                for( i=0; i<samplesPerBuffer; i++ )
                {
                    *nativeOutputBuffer++ = ((short)(outBufPtr[i] - 0x80)) << 8;
                }
                break;
            }

        default:
            break;
        }

    }

    return userResult;
}

/*************************************************************************
** Called by host code.
** Convert input from Float32, call user code, then convert output
** to Float32 format for native use.
** Assumes host native format is Float32.
** Returns result from user callback.
** FIXME - Unimplemented for formats other than paFloat32!!!!
*/
long Pa_CallConvertFloat32( internalPortAudioStream   *past,
                            float *nativeInputBuffer,
                            float *nativeOutputBuffer )
{
    long              bytesEmpty = 0;
    long              bytesFilled = 0;
    int               userResult;
    void             *inputBuffer = NULL;
    void             *outputBuffer = NULL;

    /* Get native data from DirectSound. */
    if( (past->past_NumInputChannels > 0) && (nativeInputBuffer != NULL) )
    {
        inputBuffer = nativeInputBuffer;  // FIXME
    }

    /* Are we doing output time? */
    if( (past->past_NumOutputChannels > 0) && (nativeOutputBuffer != NULL) )
    {
        /* May already be in native format so just write directly to native buffer. */
        outputBuffer = (past->past_OutputSampleFormat == paFloat32) ?
                       nativeOutputBuffer : past->past_OutputBuffer;
    }
    /*
     AddTraceMessage("Pa_CallConvertInt16: inputBuffer = ", (int) inputBuffer );
     AddTraceMessage("Pa_CallConvertInt16: outputBuffer = ", (int) outputBuffer );
    */
    /* Call user callback routine. */
    userResult = past->past_Callback(
                     inputBuffer,
                     outputBuffer,
                     past->past_FramesPerUserBuffer,
                     past->past_FrameCount,
                     past->past_UserData );

    past->past_FrameCount += (PaTimestamp) past->past_FramesPerUserBuffer;

    /* Convert to native format if necessary. */ // FIXME
    return userResult;
}

/*************************************************************************/
DLL_API PaError Pa_Initialize( void )
{
    if( gInitCount++ > 0 ) return paNoError;
    ResetTraceMessages();
    return PaHost_Init();
}

DLL_API PaError Pa_Terminate( void )
{
    PaError result = paNoError;

    if( gInitCount == 0 ) return paNoError;
    else if( --gInitCount == 0 )
    {
        result = PaHost_Term();
        DumpTraceMessages();
    }
    return result;
}

/*************************************************************************/
DLL_API PaError Pa_GetSampleSize( PaSampleFormat format )
{
    int size;
    switch(format )
    {

    case paUInt8:
    case paInt8:
        size = 1;
        break;

    case paInt16:
        size = 2;
        break;

    case paPackedInt24:
        size = 3;
        break;

    case paFloat32:
    case paInt32:
    case paInt24:
        size = 4;
        break;

    default:
        size = paSampleFormatNotSupported;
        break;
    }
    return (PaError) size;
}