audlinux_oss.cpp

linux下的一款播放器

/* ***** BEGIN LICENSE BLOCK *****
 * Source last modified: $Id: audlinux_oss.cpp,v 1.6.18.1 2004/07/09 02:01:42 hubbe Exp $
 * 
 * Portions Copyright (c) 1995-2004 RealNetworks, Inc. All Rights Reserved.
 * 
 * The contents of this file, and the files included with this file,
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 * Source License (the "RPSL") available at
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 * the file under the current version of the RealNetworks Community
 * Source License (the "RCSL") available at
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 * will apply. You may also obtain the license terms directly from
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 * the rights, obligations and limitations governing use of the
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#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/ioctl.h>

#include <stdio.h> 
#include <math.h> 

#include "ihxpckts.h"
#include "hxtick.h"
#include "hxprefs.h"
#include "timeval.h"
#include "hxthread.h"
#include "audlinux_oss.h"
#include "hxstrutl.h"
#include "hxprefutil.h"

//we can't set the PCM volume on the PowerPC. The sound driver
//only lets up set the master volume.
#ifdef __powerpc__
#   define HX_VOLUME  SOUND_MIXER_VOLUME
#else
#   define HX_VOLUME  SOUND_MIXER_PCM
#endif


//------------------------------------------
// Ctors and Dtors.
//------------------------------------------
CAudioOutLinux::CAudioOutLinux() :
    CAudioOutUNIX(),
    m_ulTickCount(0),
    m_ulLastBytesPlayed(0),
    m_ulLastTimeStamp(0),
    m_ulPausePosition(0),
    m_nDevID(NO_FILE_DESCRIPTOR),
    m_nMixerID(NO_FILE_DESCRIPTOR),
    m_bGetODelayFailed(TRUE),
    m_bGetOSpaceFailed(FALSE),
    m_bTestGetODelay(TRUE)
{
};

CAudioOutLinux::~CAudioOutLinux()
{
    //The mixer is opened independently of the audio device. Make sure 
    //it is closed.
    _CloseMixer();
};

//-------------------------------------------------------
// These Device Specific methods must be implemented 
// by the platform specific sub-classes.
//-------------------------------------------------------
INT16 CAudioOutLinux::_Imp_GetAudioFd(void)
{
    return m_nDevID;
}

//Devic specific method to set the audio device characteristics. Sample rate,
//bits-per-sample, etc.
//Method *must* set member vars. m_unSampleRate and m_unNumChannels.
HX_RESULT CAudioOutLinux::_SetDeviceConfig( const HXAudioFormat* pFormat )
{
    if ( m_nDevID < 0 )
        return RA_AOE_DEVNOTOPEN;

    m_wBlockSize = m_ulBytesPerGran;

    //First, we want to determine the fragment size of the device buffer.
    //We will let the device determine the number of fragments after we
    //make sure that each fragment is no bigger than our block size.
    //The minimum block size for OSS is 16 bytes and the max is 2^0xf.
    //Basically, Log-base-two(m_wBlockSize)+1.
    int nPower = 0x4;
    while( (1<<nPower)<m_wBlockSize && nPower<0xf )
    { 
        nPower++;
    }

    if( nPower > 4 )
        nPower--;
    
    //Frag info is 0xMMMMSSSS. Where
    //
    // MMMM is the total number of fragments. Set this to 7fff if you want
    //      OSS to figure it out.
    // SSSS is the size of each fragment. The size is 2^0xSSSS.
    int nFragInfo = 0x7fff0000 | nPower;

    //Now set the fragment size.
    if (ioctl(m_nDevID, SNDCTL_DSP_SETFRAGMENT, &nFragInfo) == -1)
    {
        return (m_wLastError = RA_AOE_NOTENABLED);
    }

    //Now set the format. Either 8-bit or 16-bit audio is supported.
    int      nSampleWidth  = pFormat->uBitsPerSample;
    ULONG32  nSampleRate   = pFormat->ulSamplesPerSec;
    int      numChannels   = pFormat->uChannels;
    int      nFormat1      = 0;
    int      nFormat2      = 0;
    
    if( nSampleWidth == 16)
    {
        nFormat1 = nFormat2 = AFMT_S16_NE;
    }
    else
    {
        nFormat1 = nFormat2 = AFMT_U8;
    }
    
    if(ioctl(m_nDevID, SNDCTL_DSP_SETFMT, &nFormat1) == -1)
    {
        return (  m_wLastError = RA_AOE_NOTENABLED );
    }

    //Check and see if the device supports the format we tried to set.
    //If it didn't take our only other option is unsigned 8 bit. So, if
    //that is what the device returned just use it.
    if(nFormat1!=nFormat2 && nFormat1 != AFMT_U8 )
    {
        //Just try to set AFMT_U8.
        nFormat1 = AFMT_U8;
        if(ioctl(m_nDevID, SNDCTL_DSP_SETFMT, &nFormat1) == -1)
        {
            return (  m_wLastError = RA_AOE_NOTENABLED );
        }
        if( nFormat1 != AFMT_U8 )
        {
            //No know format is supported.
            return (  m_wLastError = RA_AOE_NOTENABLED ); 
        }
    }
    //If we went to 8-bit then 
    if( nFormat1 == AFMT_U8 )
    {
        //AFMT_U8 is set.
        nSampleWidth = 8;
    }
    m_uSampFrameSize = nSampleWidth/8;
    if ( nSampleWidth != pFormat->uBitsPerSample )
    {
        ((HXAudioFormat*)pFormat)->uBitsPerSample = nSampleWidth;
    }
    
    
    // Set sampling rate, sample width, #channels.
    //
    // Make sure you set num channels before rate. If you don't it will
    // screw up SBPro  devices. Your rate will actually be 1/2 of what
    // you think it is.

    //Set number of channels. Stereo or mono.
    if (ioctl(m_nDevID, SOUND_PCM_WRITE_CHANNELS, &numChannels) == -1)
    {
        return ( m_wLastError = RA_AOE_NOTENABLED );
    }
    m_unNumChannels = numChannels;
    if ( numChannels != pFormat->uChannels )
    {
        ((HXAudioFormat*)pFormat)->uChannels = numChannels;
    }

    //Set the sample rate.
    if (ioctl(m_nDevID, SOUND_PCM_WRITE_RATE, &nSampleRate) == -1)
    {
        return ( m_wLastError = RA_AOE_NOTENABLED );
    }

    if (nSampleRate == 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.
	 */

	nSampleRate = pFormat->ulSamplesPerSec;
    }

    m_unSampleRate = nSampleRate;
    if ( nSampleRate != pFormat->ulSamplesPerSec )
    {
        ((HXAudioFormat*)pFormat)->ulSamplesPerSec = nSampleRate;
    }



    //Find out if the user wants to support old OSS drivers that don't have,
    //or support well, the iocls needed for good syncing.  SNDCTL_DSP_GETOSPACE and
    //SNDCTL_DSP_GETODELAY.
    IHXPreferences* pPreferences = NULL;
    if( m_pContext && HXR_OK == m_pContext->QueryInterface( IID_IHXPreferences, (void **) &pPreferences))
    {
	UINT32 nOldOSS = 0;
	if (HXR_OK == ReadPrefINT32(pPreferences, "SoundDriver", nOldOSS) &&
	    (nOldOSS == 1))
	{
	    m_bGetODelayFailed = TRUE;
	    m_bGetOSpaceFailed = TRUE;
	    m_bTestGetODelay = FALSE;
	}
        HX_RELEASE( pPreferences );
    }

//for now, PowerPC linux doesn't support the following ioctl call
//So, I will just make up some buffer size and live with it for
//now. You won't be able to tell the difference until you turn
//off threaded audio, then it will be block city!
#ifndef __powerpc__  
    audio_buf_info getYourInfoHere;
    if( !m_bGetOSpaceFailed )
    {
        //This call is to get how the device is set up after we have
        //set the sample rate etc. We use this to set up the buffers
        //we use for the fake pause/resume features.
        if (ioctl(m_nDevID, SNDCTL_DSP_GETOSPACE, &getYourInfoHere) == -1) 
        {
            m_wLastError = RA_AOE_NOTENABLED;
            return m_wLastError;
        }
        m_ulDeviceBufferSize = getYourInfoHere.fragsize*getYourInfoHere.fragstotal;
    }
    else
    {
        //We don't have anyway to determine how big the buffer is.
        //just guess I guess.
        m_ulDeviceBufferSize = 8192*4;
    }
#else
    m_ulDeviceBufferSize = 8192*4;
#endif

#ifdef _DEBUG
    fprintf( stderr, "Device Configured:\n");
    fprintf( stderr, "         Sample Rate: %d\n",  m_unSampleRate);
    fprintf( stderr, "        Sample Width: %d\n",  nSampleWidth);
    fprintf( stderr, "        Num channels: %d\n",  m_unNumChannels);
    fprintf( stderr, "          Block size: %d\n",  m_wBlockSize);
    fprintf( stderr, "  Device buffer size: %lu\n", m_ulDeviceBufferSize);
    fprintf( stderr, "  Supports GETOSPACE: %d\n",  !m_bGetOSpaceFailed);
    fprintf( stderr, "  Supports GETODELAY: %d\n",  !m_bGetODelayFailed);
#endif
    return RA_AOE_NOERR;
}

void CAudioOutLinux::_SyncUpTimeStamps(ULONG32 lCount)
{
    int bytes2  = 0;
    int theErr = -1;
    if( m_bTestGetODelay || !m_bGetODelayFailed )
    {
        HX_ASSERT(m_nDevID );
        theErr = ::ioctl(m_nDevID, SNDCTL_DSP_GETODELAY, &bytes2);
    }
    if( theErr != -1)
    {
	if (m_bTestGetODelay && (bytes2 != 0))
	{
	    // We've now seen SNDCTL_DSP_GETODELAY return
	    // a non-zero value so we know it is working
	    m_bTestGetODelay = FALSE;
            m_bGetODelayFailed = FALSE;
	}

	if (!m_bTestGetODelay)
	{
	    m_ulLastBytesPlayed = (UINT64)(m_ulTotalWritten+lCount-bytes2);
	    m_ulLastTimeStamp   = GetTickCount();
	}
    }
    else
    {
        //so we don't try it again.
        m_bGetODelayFailed = TRUE;
	m_bTestGetODelay = FALSE;
    }
}


//Device specific method to write bytes out to the audiodevice and return a
//count of bytes written. 
HX_RESULT CAudioOutLinux::_WriteBytes( UCHAR* buffer, ULONG32 ulBuffLength, LONG32& lCount )
{
    HX_RESULT retCode = RA_AOE_NOERR;

    if( m_nDevID < 0 )
    {
        retCode = RA_AOE_DEVNOTOPEN;
    }
    else
    {
        if( m_ulTickCount == 0 )
            m_ulTickCount = GetTickCount();

        lCount = ::write( m_nDevID, buffer, ulBuffLength);
        if( lCount < 0 )
        {
            //Error occurred.
            if( errno == EAGAIN )
                retCode = RA_AOE_NOERR;
            if( errno == EINTR )
                retCode = RA_AOE_DEVBUSY;
        }
        else
        {
            _SyncUpTimeStamps(lCount);
        }
    }
    return retCode;
}

//Device specific methods to open/close the mixer and audio devices.
HX_RESULT CAudioOutLinux::_OpenAudio()
{
    HX_RESULT retCode = RA_AOE_NOERR;

    //Set the tick count to zero
    m_ulTickCount       = 0;
    m_ulLastTimeStamp   = 0;
    m_ulLastBytesPlayed = 0;
    m_ulPausePosition   = 0;

    //Check the environmental variable to let user overide default device.
    char *pszOverrideName = getenv( "AUDIO" ); /* Flawfinder: ignore */
    char szDevName[MAX_DEV_NAME]; /* Flawfinder: ignore */
    
    // Use defaults if no environment variable is set.
    if ( pszOverrideName && strlen(pszOverrideName)>0 )
    {
        SafeStrCpy( szDevName, pszOverrideName, MAX_DEV_NAME );
    }
    else
    {