audlinux_oss.cpp

linux下的一款播放器

        SafeStrCpy( szDevName, "/dev/dsp", MAX_DEV_NAME );
    }
    
    // Open the audio device if it isn't already open
    if ( m_nDevID < 0 )
    {
        m_nDevID = ::open( szDevName, O_WRONLY );
    }
    
    if ( m_nDevID < 0 )
    {
#ifdef _DEBUG        
        fprintf( stderr, "Failed to open audio(%s)!!!!!!! Code is: %d  errno: %d\n",
                 szDevName, m_nDevID, errno );
#endif        
        
        //Error opening device.
        retCode = RA_AOE_BADOPEN;
    }
    
    m_wLastError = retCode;
    return m_wLastError;
}

HX_RESULT CAudioOutLinux::_CloseAudio()
{
    HX_RESULT retCode = RA_AOE_NOERR;
    
    if( m_nDevID >= 0 )
    {
        ::close( m_nDevID );
        m_nDevID = NO_FILE_DESCRIPTOR;
    }
    else
    {
        retCode = RA_AOE_DEVNOTOPEN;
    }
    m_wLastError = retCode;
    return m_wLastError;
}

HX_RESULT CAudioOutLinux::_OpenMixer()
{
    HX_RESULT retCode = RA_AOE_NOERR;

    if(!m_bMixerPresent)
    {
        //Let user override default device with environ variable.
        char *pszOverrideName = getenv( "MIXER" ); /* Flawfinder: ignore */
        char szDevCtlName[MAX_DEV_NAME]; /* Flawfinder: ignore */
        
        if (pszOverrideName && strlen(pszOverrideName)>0 )
	{
            SafeStrCpy( szDevCtlName , pszOverrideName, MAX_DEV_NAME );
	}
        else
	{
            SafeStrCpy( szDevCtlName , "/dev/mixer", MAX_DEV_NAME );	// default for volume
	}
        
        m_nMixerID = ::open( szDevCtlName, O_RDWR );
        
        if (m_nMixerID > 0)
        {
            m_bMixerPresent = 1;
            _Imp_GetVolume();
        }
        else
        {
            m_nMixerID = NO_FILE_DESCRIPTOR;
            m_bMixerPresent = 0;
        }
    }

    m_wLastError = retCode;
    return m_wLastError;
}

HX_RESULT CAudioOutLinux::_CloseMixer()
{
    HX_RESULT retCode = RA_AOE_NOERR;

    if( m_nMixerID >= 0 )
    {
        ::close( m_nMixerID );
        m_nMixerID = NO_FILE_DESCRIPTOR;
    }
    
    m_wLastError = retCode;
    return m_wLastError;
}

//Device specific method to reset device and return it to a state that it 
//can accept new sample rates, num channels, etc.
HX_RESULT CAudioOutLinux::_Reset()
{
    HX_RESULT retCode = RA_AOE_NOERR;

    m_ulPausePosition = 0;
    
    if ( m_nDevID < 0 )
    {
        retCode = RA_AOE_DEVNOTOPEN;
    }
    else if( ::ioctl (m_nDevID, SOUND_PCM_RESET, 0) == -1 )
    {
        retCode = RA_AOE_GENERAL;
    }

    m_wLastError = retCode;
    return m_wLastError;
}

//Device specific method to get/set the devices current volume.
UINT16 CAudioOutLinux::_GetVolume() const
{
    int nVolume      = 0;
    int nRetVolume   = 0;
    int nLeftVolume  = 0;
    int nRightVolume = 0;
    
    if (::ioctl( m_nMixerID, MIXER_READ(HX_VOLUME), &nVolume) < 0)
    {
        nRetVolume = 0;
    }
    nLeftVolume  = (nVolume & 0x000000ff); 
    nRightVolume = (nVolume & 0x0000ff00) >> 8;

    //Which one to use? Average them?
    nRetVolume = nLeftVolume ;

    return nRetVolume; 
}

HX_RESULT CAudioOutLinux::_SetVolume(UINT16 unVolume)
{
    HX_RESULT retCode = RA_AOE_NOERR;
    
    int nNewVolume=0;

    //Set both left and right volumes.
    nNewVolume = (unVolume & 0xff) | ((unVolume &0xff) << 8);
    
    if (::ioctl( m_nMixerID, MIXER_WRITE(HX_VOLUME), &nNewVolume) < 0)
    {
        retCode = RA_AOE_NOTSUPPORTED;
    }

    m_wLastError = retCode;
    return m_wLastError;
}

//Device specific method to drain a device. This should play the remaining
//bytes in the devices buffer and then return.
HX_RESULT CAudioOutLinux::_Drain()
{
    HX_RESULT retCode = RA_AOE_NOERR;
    
    if ( m_nDevID < 0 )
    {
        retCode = RA_AOE_DEVNOTOPEN;
    }
    else if( ::ioctl (m_nDevID, SNDCTL_DSP_SYNC, 0) == -1 )
    {
        retCode = RA_AOE_GENERAL;
    }

    m_wLastError = retCode;
    return m_wLastError;
}



UINT64 CAudioOutLinux::_GetBytesActualyPlayed(void) const
{
    /* Get current playback position in device DMA. */
    int     bytes2 = 0;
    UINT64  ulTheAnswer = 0;

    //What versions of the linux kernel do we want to support?
    if( !m_bGetODelayFailed )
    {
        if( m_ulTotalWritten > 0 )
        {
            HX_ASSERT( m_unSampleRate!=0 && m_uSampFrameSize!=0 );
            ULONG32 ulTick = GetTickCount();

            //We need to update the timestamps every so often.
            //This make sure that if the XServer was blocked, and
            //we ran dry, that we re-sync up.
            if( (ulTick-m_ulLastTimeStamp)>200 )
            {
                ((CAudioOutLinux*)this)->_SyncUpTimeStamps();
                ulTick = GetTickCount();
            }
            
            ulTheAnswer = (UINT64)(m_ulLastBytesPlayed+
            ((float)(ulTick-m_ulLastTimeStamp)*
             (float)m_unNumChannels/1000.0*
             m_unSampleRate*m_uSampFrameSize) +0.5 );
        }
    }
    else
    {
        //We will assume that the error is because of an incomplete 
        //implementation of the oss compatible driver. So, just 
        //fake it with time stamps.
        if( m_ulTotalWritten > 0 )
        {
            ulTheAnswer = (UINT64)((float)(GetTickCount()-m_ulTickCount)*(float)m_unNumChannels/1000.0*m_unSampleRate*m_uSampFrameSize);
            ulTheAnswer += m_ulPausePosition;
        }
    }
    return  ulTheAnswer;
}


//this must return the number of bytes that can be written without blocking.
//Don't use SNDCTL_DSP_GETODELAY here as it can't compute that amount
//correctly.
HX_RESULT CAudioOutLinux::_GetRoomOnDevice(ULONG32& ulBytes) const
{
    HX_RESULT      retCode = RA_AOE_NOERR;
    audio_buf_info stBuffInfo;
    int            theErr=0;

    //What versions of the linux kernel do we want to support?
    if( m_bGetOSpaceFailed )
    {
        theErr = -1;
    }
    else
    {
        theErr = ::ioctl(m_nDevID, SNDCTL_DSP_GETOSPACE, &stBuffInfo);
    }

    if ( theErr != -1 )
    {
        ulBytes = stBuffInfo.bytes;
    }
    else
    {
        //So we just try it once.
        m_bGetOSpaceFailed = TRUE;
        ulBytes = m_ulDeviceBufferSize-(m_ulTotalWritten-_GetBytesActualyPlayed() );
    }

    m_wLastError = retCode;
    return m_wLastError;
}

HX_RESULT CAudioOutLinux::_CheckFormat( const HXAudioFormat* pFormat )
{
    int   nBitsPerSample = pFormat->uBitsPerSample;
    int   ulTmp          = pFormat->ulSamplesPerSec;    
    int   nNumChannels   = pFormat->uChannels;
    float fTmp           = 0.0;

    HX_RESULT retCode = RA_AOE_NOERR;
    
    //Is the device already open?
    if( m_nDevID > 0 || RA_AOE_NOERR != _OpenAudio() )
    {
        retCode = RA_AOE_DEVBUSY;
        return retCode;
    }

    //See if the sample rate is supported.
    if (ioctl(m_nDevID, SOUND_PCM_WRITE_RATE, &ulTmp) == -1)
    {
        //Not quite the real error, but it is what we need to return.
        retCode = RA_AOE_DEVBUSY;
        goto donechecking;
    }

    if (ulTmp == 0)
    {
	/* 
	 * Some drivers actually set the sample rate on the device, but
	 * return 0 for the sample rate. On these platforms we just ignore
	 * the return value and assume the sample rate is set to what was
	 * requested.
	 */

	ulTmp = pFormat->ulSamplesPerSec;
    }

    //The ESS 1688 Sound card (not the ESS Solo-1) will return sample
    //rates that are close but not quite the ones we asked for (the
    //ESS Solo-1 doesn't play mono). I have see freqs like 44194
    //instead of 44100 (.2%) and 7984 instead of 8000 (.6%).
    //So, if we are close enough just say it is OK. 
    //How about 1%?
    fTmp = (float)ulTmp/(float)pFormat->ulSamplesPerSec;
    if( fabs(1.0-fTmp) > .01 )
    {
        //It is NOT supported
        retCode = RA_AOE_BADFORMAT;
        goto donechecking;
    }

    //Check num channels.
    if (ioctl(m_nDevID, SOUND_PCM_WRITE_CHANNELS, &nNumChannels) == -1)
    {
        retCode = RA_AOE_DEVBUSY;
        goto donechecking;
    }
    else if ( nNumChannels != pFormat->uChannels )
    {
        retCode = RA_AOE_BADFORMAT;
        goto donechecking;
    }

    //Check the frame size.
    if (ioctl(m_nDevID, SNDCTL_DSP_SETFMT, &nBitsPerSample) == -1)
    {
       retCode = RA_AOE_DEVBUSY;
       goto donechecking;
    }
    else if ( nBitsPerSample != pFormat->uBitsPerSample )
    {
        retCode = RA_AOE_BADFORMAT;
        goto donechecking;
    }

    //Close the audio device.
  donechecking:
    _CloseAudio();
    m_wLastError = retCode;
    return retCode;
}


HX_RESULT CAudioOutLinux::_CheckSampleRate( ULONG32 ulSampleRate )
{
    ULONG32 ulTmp = ulSampleRate;

    m_wLastError = RA_AOE_NOERR;
    
    //Is the device already open?
    if( m_nDevID > 0 || RA_AOE_NOERR != _OpenAudio() )
    {
        m_wLastError = RA_AOE_DEVBUSY;
    }
    else
    {   
        //See if the sample rate is supported.
        if (ioctl(m_nDevID, SOUND_PCM_WRITE_RATE, &ulTmp) == -1)
        {
            //Not quite the real error, but it is what we need to return.
            m_wLastError = RA_AOE_DEVBUSY;
        }
        else if( ulSampleRate != ulTmp )
        {
            //It is NOT supported
            m_wLastError = RA_AOE_BADFORMAT;
        }
        
        _CloseAudio();
    }
    
    return m_wLastError;
}


HX_RESULT CAudioOutLinux::_Pause() 
{
    m_wLastError = HXR_OK;
    m_ulPausePosition = m_ulTotalWritten;
    m_ulTickCount = 0;
    m_ulLastTimeStamp   = 0;
    return m_wLastError;
}

HX_RESULT CAudioOutLinux::_Resume()
{
    m_wLastError = HXR_OK;

    if( m_ulTotalWritten > 0 )
    {
        m_ulTickCount = GetTickCount();
        m_ulLastTimeStamp = m_ulTickCount;
    }
    return m_wLastError;
}