jamulus/src/channel.cpp

/******************************************************************************\
 * Copyright (c) 2004-2008
 *
 * Author(s):
 *  Volker Fischer
 *
 ******************************************************************************
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later 
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT 
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
\******************************************************************************/

#include "channel.h"


/******************************************************************************\
* CChannelSet                                                                  *
\******************************************************************************/
CChannelSet::CChannelSet()
{
    // enable all channels
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        vecChannels[i].SetEnable ( true );
    }

    // CODE TAG: MAX_NUM_CHANNELS_TAG
    // make sure we have MAX_NUM_CHANNELS connections!!!
    // send message
    QObject::connect ( &vecChannels[0], SIGNAL ( MessReadyForSending ( CVector<uint8_t> ) ), this, SLOT ( OnSendProtMessCh0 ( CVector<uint8_t> ) ) );
    QObject::connect ( &vecChannels[1], SIGNAL ( MessReadyForSending ( CVector<uint8_t> ) ), this, SLOT ( OnSendProtMessCh1 ( CVector<uint8_t> ) ) );
    QObject::connect ( &vecChannels[2], SIGNAL ( MessReadyForSending ( CVector<uint8_t> ) ), this, SLOT ( OnSendProtMessCh2 ( CVector<uint8_t> ) ) );
    QObject::connect ( &vecChannels[3], SIGNAL ( MessReadyForSending ( CVector<uint8_t> ) ), this, SLOT ( OnSendProtMessCh3 ( CVector<uint8_t> ) ) );
    QObject::connect ( &vecChannels[4], SIGNAL ( MessReadyForSending ( CVector<uint8_t> ) ), this, SLOT ( OnSendProtMessCh4 ( CVector<uint8_t> ) ) );
    QObject::connect ( &vecChannels[5], SIGNAL ( MessReadyForSending ( CVector<uint8_t> ) ), this, SLOT ( OnSendProtMessCh5 ( CVector<uint8_t> ) ) );

    // request jitter buffer size
    QObject::connect ( &vecChannels[0], SIGNAL ( NewConnection()), this, SLOT ( OnNewConnectionCh0() ) );
    QObject::connect ( &vecChannels[1], SIGNAL ( NewConnection()), this, SLOT ( OnNewConnectionCh1() ) );
    QObject::connect ( &vecChannels[2], SIGNAL ( NewConnection()), this, SLOT ( OnNewConnectionCh2() ) );
    QObject::connect ( &vecChannels[3], SIGNAL ( NewConnection()), this, SLOT ( OnNewConnectionCh3() ) );
    QObject::connect ( &vecChannels[4], SIGNAL ( NewConnection()), this, SLOT ( OnNewConnectionCh4() ) );
    QObject::connect ( &vecChannels[5], SIGNAL ( NewConnection()), this, SLOT ( OnNewConnectionCh5() ) );

    // request connected clients list
    QObject::connect ( &vecChannels[0], SIGNAL ( ReqConnClientsList() ), this, SLOT ( OnReqConnClientsListCh0() ) );
    QObject::connect ( &vecChannels[1], SIGNAL ( ReqConnClientsList() ), this, SLOT ( OnReqConnClientsListCh1() ) );
    QObject::connect ( &vecChannels[2], SIGNAL ( ReqConnClientsList() ), this, SLOT ( OnReqConnClientsListCh2() ) );
    QObject::connect ( &vecChannels[3], SIGNAL ( ReqConnClientsList() ), this, SLOT ( OnReqConnClientsListCh3() ) );
    QObject::connect ( &vecChannels[4], SIGNAL ( ReqConnClientsList() ), this, SLOT ( OnReqConnClientsListCh4() ) );
    QObject::connect ( &vecChannels[5], SIGNAL ( ReqConnClientsList() ), this, SLOT ( OnReqConnClientsListCh5() ) );

    // channel name has changed
    QObject::connect ( &vecChannels[0], SIGNAL ( NameHasChanged() ), this, SLOT ( OnNameHasChangedCh0() ) );
    QObject::connect ( &vecChannels[1], SIGNAL ( NameHasChanged() ), this, SLOT ( OnNameHasChangedCh1() ) );
    QObject::connect ( &vecChannels[2], SIGNAL ( NameHasChanged() ), this, SLOT ( OnNameHasChangedCh2() ) );
    QObject::connect ( &vecChannels[3], SIGNAL ( NameHasChanged() ), this, SLOT ( OnNameHasChangedCh3() ) );
    QObject::connect ( &vecChannels[4], SIGNAL ( NameHasChanged() ), this, SLOT ( OnNameHasChangedCh4() ) );
    QObject::connect ( &vecChannels[5], SIGNAL ( NameHasChanged() ), this, SLOT ( OnNameHasChangedCh5() ) );

    // chat text received
    QObject::connect ( &vecChannels[0], SIGNAL ( ChatTextReceived ( QString ) ), this, SLOT ( OnChatTextReceivedCh0 ( QString ) ) );
    QObject::connect ( &vecChannels[1], SIGNAL ( ChatTextReceived ( QString ) ), this, SLOT ( OnChatTextReceivedCh1 ( QString ) ) );
    QObject::connect ( &vecChannels[2], SIGNAL ( ChatTextReceived ( QString ) ), this, SLOT ( OnChatTextReceivedCh2 ( QString ) ) );
    QObject::connect ( &vecChannels[3], SIGNAL ( ChatTextReceived ( QString ) ), this, SLOT ( OnChatTextReceivedCh3 ( QString ) ) );
    QObject::connect ( &vecChannels[4], SIGNAL ( ChatTextReceived ( QString ) ), this, SLOT ( OnChatTextReceivedCh4 ( QString ) ) );
    QObject::connect ( &vecChannels[5], SIGNAL ( ChatTextReceived ( QString ) ), this, SLOT ( OnChatTextReceivedCh5 ( QString ) ) );

    // ping message received
    QObject::connect ( &vecChannels[0], SIGNAL ( PingReceived ( QTime ) ), this, SLOT ( OnPingReceivedCh0 ( QTime ) ) );
    QObject::connect ( &vecChannels[1], SIGNAL ( PingReceived ( QTime ) ), this, SLOT ( OnPingReceivedCh1 ( QTime ) ) );
    QObject::connect ( &vecChannels[2], SIGNAL ( PingReceived ( QTime ) ), this, SLOT ( OnPingReceivedCh2 ( QTime ) ) );
    QObject::connect ( &vecChannels[3], SIGNAL ( PingReceived ( QTime ) ), this, SLOT ( OnPingReceivedCh3 ( QTime ) ) );
    QObject::connect ( &vecChannels[4], SIGNAL ( PingReceived ( QTime ) ), this, SLOT ( OnPingReceivedCh4 ( QTime ) ) );
    QObject::connect ( &vecChannels[5], SIGNAL ( PingReceived ( QTime ) ), this, SLOT ( OnPingReceivedCh5 ( QTime ) ) );
}

CVector<CChannelShortInfo> CChannelSet::CreateChannelList()
{
    CVector<CChannelShortInfo> vecChanInfo ( 0 );

    // look for free channels
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        if ( vecChannels[i].IsConnected() )
        {
            // append channel ID, IP address and channel name to storing vectors
            vecChanInfo.Add ( CChannelShortInfo (
                i, // ID
                vecChannels[i].GetAddress().InetAddr.toIPv4Address(), // IP address
                vecChannels[i].GetName() /* name */ ) );
        }
    }

    return vecChanInfo;
}

void CChannelSet::CreateAndSendChanListForAllConChannels()
{
    // create channel list
    CVector<CChannelShortInfo> vecChanInfo ( CChannelSet::CreateChannelList() );

    // now send connected channels list to all connected clients
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        if ( vecChannels[i].IsConnected() )
        {
            // send message
            vecChannels[i].CreateConClientListMes ( vecChanInfo );
        }
    }
}

void CChannelSet::CreateAndSendChanListForAllExceptThisChan ( const int iCurChanID )
{
    // create channel list
    CVector<CChannelShortInfo> vecChanInfo ( CChannelSet::CreateChannelList() );

    // now send connected channels list to all connected clients except for
    // the channel with the ID "iCurChanID"
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        if ( ( vecChannels[i].IsConnected() ) && ( i != iCurChanID ) )
        {
            // send message
            vecChannels[i].CreateConClientListMes ( vecChanInfo );
        }
    }
}

void CChannelSet::CreateAndSendChanListForThisChan ( const int iCurChanID )
{
    // create channel list
    CVector<CChannelShortInfo> vecChanInfo ( CChannelSet::CreateChannelList() );

    // now send connected channels list to the channel with the ID "iCurChanID"
    vecChannels[iCurChanID].CreateConClientListMes ( vecChanInfo );
}

void CChannelSet::CreateAndSendChatTextForAllConChannels ( const int iCurChanID,
                                                           const QString& strChatText )
{
    // create message which is sent to all connected clients -------------------
    // get client name, if name is empty, use IP address instead
    QString ChanName = vecChannels[iCurChanID].GetName();
    if ( ChanName.isEmpty() )
    {
        // convert IP address to text and show it
        const QHostAddress addrTest ( vecChannels[iCurChanID].GetAddress().InetAddr );
        ChanName = addrTest.toString();
    }

    // add name of the client at the beginning of the message text
    const QString strActualMessageText =
        "<" + ChanName + "> " + strChatText;


    // send chat text to all connected clients ---------------------------------
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        if ( vecChannels[i].IsConnected() )
        {
            // send message
            vecChannels[i].CreateChatTextMes ( strActualMessageText );
        }
    }
}

int CChannelSet::GetFreeChan()
{
    // look for a free channel
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        if ( !vecChannels[i].IsConnected() )
        {
            return i;
        }
    }

    /* no free channel found, return invalid ID */
    return INVALID_CHANNEL_ID;
}

int CChannelSet::CheckAddr ( const CHostAddress& Addr )
{
    CHostAddress InetAddr;

    /* Check for all possible channels if IP is already in use */
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        if ( vecChannels[i].GetAddress ( InetAddr ) )
        {
            /* IP found, return channel number */
            if ( InetAddr == Addr )
            {
                return i;
            }
        }
    }

    /* IP not found, return invalid ID */
    return INVALID_CHANNEL_ID;
}

bool CChannelSet::PutData ( const CVector<unsigned char>& vecbyRecBuf,
                            const int                     iNumBytesRead,
                            const CHostAddress&           HostAdr )
{
    bool bRet            = false;
    bool bCreateChanList = false;

    Mutex.lock();
    {
        bool bChanOK = true;

        // get channel ID ------------------------------------------------------
        // check address
        int iCurChanID = CheckAddr ( HostAdr );

        if ( iCurChanID == INVALID_CHANNEL_ID )
        {
            // a new client is calling, look for free channel
            iCurChanID = GetFreeChan();

            if ( iCurChanID != INVALID_CHANNEL_ID )
            {
                // initialize current channel by storing the calling host
                // address
                vecChannels[iCurChanID].SetAddress ( HostAdr );

                // reset the channel gains of current channel, at the same
                // time reset gains of this channel ID for all other channels
                for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
                {
                    vecChannels[iCurChanID].SetGain ( i, (double) 1.0 );

                    // other channels (we do not distinguish the case if
                    // i == iCurChanID for simplicity)
                    vecChannels[i].SetGain ( iCurChanID, (double) 1.0 );
                }

                // a new client connected to the server, set flag to create and
                // send all clients the updated channel list, we cannot create
                // the message here since the received data has to be put to the
                // channel first so that this channel is marked as connected
                bCreateChanList = true;
            }
            else
            {
                // no free channel available
                bChanOK = false;

                // create and send "server full" message

// TODO problem: if channel is not officially connected, we cannot send messages

            }
        }


        // put received data in jitter buffer ----------------------------------
        if ( bChanOK )
        {
            // put packet in socket buffer
            switch ( vecChannels[iCurChanID].PutData ( vecbyRecBuf, iNumBytesRead ) )
            {
            case PS_AUDIO_OK:
                PostWinMessage ( MS_JIT_BUF_PUT, MUL_COL_LED_GREEN, iCurChanID );
                bRet = true; // in case we have an audio packet, return true
                break;

            case PS_AUDIO_ERR:
                PostWinMessage ( MS_JIT_BUF_PUT, MUL_COL_LED_RED, iCurChanID );
                bRet = true; // in case we have an audio packet, return true
                break;

            case PS_PROT_ERR:
                PostWinMessage ( MS_JIT_BUF_PUT, MUL_COL_LED_YELLOW, iCurChanID );
                break;
            }
        }


        // after data is put in channel buffer, create channel list message if
        // requested
        if ( bCreateChanList )
        {
            // connected clients list is only send for new connected clients after
            // request, only the already connected clients get the list
            // automatically, because they don't know when new clients connect
            CreateAndSendChanListForAllExceptThisChan ( iCurChanID );
        }
    }
    Mutex.unlock();

    return bRet;
}

void CChannelSet::GetBlockAllConC ( CVector<int>&              vecChanID,
                                    CVector<CVector<double> >& vecvecdData,
                                    CVector<CVector<double> >& vecvecdGains )
{
    int  i, j;
    bool bCreateChanList = false;

    // init temporal data vector and clear input buffers
    CVector<double> vecdData ( MIN_BLOCK_SIZE_SAMPLES );

    vecChanID.Init    ( 0 );
    vecvecdData.Init  ( 0 );
    vecvecdGains.Init ( 0 );

    // make put and get calls thread safe. Do not forget to unlock mutex
    // afterwards!
    Mutex.lock();
    {
        // check all possible channels
        for ( i = 0; i < MAX_NUM_CHANNELS; i++ )
        {
            // read out all input buffers to decrease timeout counter on
            // disconnected channels
            const EGetDataStat eGetStat = vecChannels[i].GetData ( vecdData );

            // if channel was just disconnected, set flag that connected
            // client list is sent to all other clients
            if ( eGetStat == GS_CHAN_NOW_DISCONNECTED )
            {
                bCreateChanList = true;
            }

            if ( vecChannels[i].IsConnected() )
            {
                // add ID and data
                vecChanID.Add ( i );

                const int iOldSize = vecvecdData.Size();
                vecvecdData.Enlarge ( 1 );
                vecvecdData[iOldSize].Init ( vecdData.Size() );
                vecvecdData[iOldSize] = vecdData;

                // send message for get status (for GUI)
                if ( eGetStat == GS_BUFFER_OK )
                {
                    PostWinMessage ( MS_JIT_BUF_GET, MUL_COL_LED_GREEN, i );
                }
                else
                {
                    PostWinMessage ( MS_JIT_BUF_GET, MUL_COL_LED_RED, i );
                }
            }
        }

        // now that we know the IDs of the connected clients, get gains
        const int iNumCurConnChan = vecChanID.Size();
        vecvecdGains.Init ( iNumCurConnChan );

        for ( i = 0; i < iNumCurConnChan; i++ )
        {
            vecvecdGains[i].Init ( iNumCurConnChan );

            for ( j = 0; j < iNumCurConnChan; j++ )
            {
                // The second index of "vecvecdGains" does not represent
                // the channel ID! Therefore we have to use "vecChanID" to
                // query the IDs of the currently connected channels
                vecvecdGains[i][j] =
                    vecChannels[ vecChanID[i] ].GetGain( vecChanID[j] );
            }
        }

        // create channel list message if requested
        if ( bCreateChanList )
        {
            // update channel list for all currently connected clients
            CreateAndSendChanListForAllConChannels();
        }
    }
    Mutex.unlock(); // release mutex
}

void CChannelSet::GetConCliParam ( CVector<CHostAddress>& vecHostAddresses,
                                   CVector<QString>&      vecsName,
                                   CVector<int>&          veciJitBufSize,
                                   CVector<int>&          veciNetwOutBlSiFact,
                                   CVector<int>&          veciNetwInBlSiFact )
{
    CHostAddress InetAddr;

    // init return values
    vecHostAddresses.Init    ( MAX_NUM_CHANNELS );
    vecsName.Init            ( MAX_NUM_CHANNELS );
    veciJitBufSize.Init      ( MAX_NUM_CHANNELS );
    veciNetwOutBlSiFact.Init ( MAX_NUM_CHANNELS );
    veciNetwInBlSiFact.Init  ( MAX_NUM_CHANNELS );

    // check all possible channels
    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
    {
        if ( vecChannels[i].GetAddress ( InetAddr ) )
        {
            // get requested data
            vecHostAddresses[i]    = InetAddr;
            vecsName[i]            = vecChannels[i].GetName();
            veciJitBufSize[i]      = vecChannels[i].GetSockBufSize();
            veciNetwOutBlSiFact[i] = vecChannels[i].GetNetwBufSizeFactOut();
            veciNetwInBlSiFact[i]  = vecChannels[i].GetNetwBufSizeFactIn();
        }
    }
}


/******************************************************************************\
* CChannel                                                                     *
\******************************************************************************/
CChannel::CChannel() : sName ( "" ),
    vecdGains ( MAX_NUM_CHANNELS, (double) 1.0 )
{
    // query all possible network in buffer sizes for determining if an
    // audio packet was received
    for ( int i = 0; i < MAX_NET_BLOCK_SIZE_FACTOR; i++ )
    {
        // network block size factor must start from 1 -> ( i + 1 )
        vecNetwInBufSizes[i] = AudioCompressionIn.Init (
            ( i + 1 ) * MIN_BLOCK_SIZE_SAMPLES,
            CAudioCompression::CT_IMAADPCM );
    }

    iCurNetwInBlSiFact = DEF_NET_BLOCK_SIZE_FACTOR;

    // init the socket buffer
    SetSockBufSize ( DEF_NET_BUF_SIZE_NUM_BL );

    // set initial input and output block size factors
    SetNetwBufSizeFactOut ( iCurNetwInBlSiFact );
    SetNetwInBlSiFact ( iCurNetwInBlSiFact );

    // init time-out for the buffer with zero -> no connection
    iConTimeOut = 0;


    // connections -------------------------------------------------------------
    QObject::connect ( &Protocol,
        SIGNAL ( MessReadyForSending ( CVector<uint8_t> ) ),
        this, SLOT ( OnSendProtMessage ( CVector<uint8_t> ) ) );

    QObject::connect ( &Protocol,
        SIGNAL ( ChangeJittBufSize ( int ) ),
        this, SLOT ( OnJittBufSizeChange ( int ) ) );

    QObject::connect ( &Protocol,
        SIGNAL ( ReqJittBufSize() ),
        SIGNAL ( ReqJittBufSize() ) );

    QObject::connect ( &Protocol,
        SIGNAL ( ReqConnClientsList() ),
        SIGNAL ( ReqConnClientsList() ) );

    QObject::connect ( &Protocol,
        SIGNAL ( ConClientListMesReceived ( CVector<CChannelShortInfo> ) ),
        SIGNAL ( ConClientListMesReceived ( CVector<CChannelShortInfo> ) ) );

    QObject::connect ( &Protocol,
        SIGNAL ( ChangeNetwBlSiFact ( int ) ),
        this, SLOT ( OnNetwBlSiFactChange ( int ) ) );

    QObject::connect( &Protocol, SIGNAL ( ChangeChanGain ( int, double ) ),
        this, SLOT ( OnChangeChanGain ( int, double ) ) );

    QObject::connect( &Protocol, SIGNAL ( ChangeChanName ( QString ) ),
        this, SLOT ( OnChangeChanName ( QString ) ) );

    QObject::connect( &Protocol, SIGNAL ( ChatTextReceived ( QString ) ),
        this, SIGNAL ( ChatTextReceived ( QString ) ) );

    QObject::connect( &Protocol, SIGNAL ( PingReceived ( QTime ) ),
        this, SIGNAL ( PingReceived ( QTime ) ) );
}

void CChannel::SetEnable ( const bool bNEnStat )
{
    // set internal parameter
    bIsEnabled = bNEnStat;

    // if channel is not enabled, reset time out count
    if ( !bNEnStat )
    {
        iConTimeOut = 0;
    }
}

void CChannel::SetNetwInBlSiFact ( const int iNewBlockSizeFactor )
{
    // store new value
    iCurNetwInBlSiFact = iNewBlockSizeFactor;

    // init audio compression unit
    iAudComprSizeIn = AudioCompressionIn.Init (
        iNewBlockSizeFactor * MIN_BLOCK_SIZE_SAMPLES,
        CAudioCompression::CT_IMAADPCM );

    // initial value for connection time out counter
    iConTimeOutStartVal = ( CON_TIME_OUT_SEC_MAX * 1000 ) /
        ( iNewBlockSizeFactor * MIN_BLOCK_DURATION_MS );

    // socket buffer must be adjusted
    SetSockBufSize ( GetSockBufSize() );
}

void CChannel::SetNetwBufSizeFactOut ( const int iNewNetwBlSiFactOut )
{
    // store new value
    iCurNetwOutBlSiFact = iNewNetwBlSiFactOut;

    // init audio compression unit
    iAudComprSizeOut = AudioCompressionOut.Init (
        iNewNetwBlSiFactOut * MIN_BLOCK_SIZE_SAMPLES,
        CAudioCompression::CT_IMAADPCM );

    // init conversion buffer
    ConvBuf.Init ( iNewNetwBlSiFactOut * MIN_BLOCK_SIZE_SAMPLES );
}

void CChannel::OnSendProtMessage ( CVector<uint8_t> vecMessage )
{
    // only send messages if we are connected, otherwise delete complete queue
    if ( IsConnected() )
    {
        // emit message to actually send the data
        emit MessReadyForSending ( vecMessage );
    }
    else
    {
        // delete send message queue
        Protocol.DeleteSendMessQueue();
    }
}

void CChannel::SetSockBufSize ( const int iNumBlocks )
{
    // this opperation must be done with mutex
    Mutex.lock();
    {
        iCurSockBufSize = iNumBlocks;

        // the idea of setting the jitter buffer is as follows:
        // The network block size is a multiple of the internal minimal
        // block size. Therefore, the minimum jitter buffer size must be
        // so that it can take one network buffer -> NET_BLOCK_SIZE_FACTOR.
        // The actual jitter compensation are then the additional blocks of
        // the internal block size, which is set with SetSockBufSize
        SockBuf.Init ( MIN_BLOCK_SIZE_SAMPLES,
            iNumBlocks + iCurNetwInBlSiFact );
    }
    Mutex.unlock();
}

void CChannel::OnNetwBlSiFactChange ( int iNewNetwBlSiFact )
{
// TEST
//qDebug ( "new network block size factor: %d", iNewNetwBlSiFact );

    SetNetwBufSizeFactOut ( iNewNetwBlSiFact );
}

void CChannel::OnJittBufSizeChange ( int iNewJitBufSize )
{
// TEST
//qDebug ( "new jitter buffer size: %d", iNewJitBufSize );

    SetSockBufSize ( iNewJitBufSize );
}

void CChannel::OnChangeChanGain ( int iChanID, double dNewGain )
{
    Q_ASSERT ( ( iChanID >= 0 ) && ( iChanID < MAX_NUM_CHANNELS ) );

    // set value
    vecdGains[iChanID] = dNewGain;
}

void CChannel::OnChangeChanName ( QString strName )
{
    // apply value (if different from previous name)
    if ( sName.compare ( strName ) )
    {
        sName = strName;

        // fire message that name has changed
        emit NameHasChanged();
    }
}

bool CChannel::GetAddress(CHostAddress& RetAddr)
{
    if ( IsConnected() )
    {
        RetAddr = InetAddr;
        return true;
    }
    else
    {
        RetAddr = CHostAddress();
        return false;
    }
}

EPutDataStat CChannel::PutData ( const CVector<unsigned char>& vecbyData,
                                 int iNumBytes )
{
    EPutDataStat eRet = PS_GEN_ERROR;

    // init flags
    bool bIsProtocolPacket = false;
    bool bIsAudioPacket    = false;
    bool bNewConnection    = false;

    if ( bIsEnabled )
    {
        // first check if this is protocol data
        // only use protocol data if channel is connected
        if ( IsConnected() )
        {
            // this seems not to be an audio block, parse the message
            if ( Protocol.ParseMessage ( vecbyData, iNumBytes ) )
            {
                // set status flags
                eRet              = PS_PROT_OK;
                bIsProtocolPacket = true;

                // create message for protocol status
                emit ProtocolStatus ( true );
            }
        }

        // only try to parse audio if it was not a protocol packet
        if ( !bIsProtocolPacket )
        {
            // check if this is an audio packet by checking all possible lengths
            for ( int i = 0; i < MAX_NET_BLOCK_SIZE_FACTOR; i++ )
            {
                if ( iNumBytes == vecNetwInBufSizes[i] )
                {
                    bIsAudioPacket = true;

                    // check if we are correctly initialized
                    const int iNewNetwInBlSiFact = i + 1;
                    if ( iNewNetwInBlSiFact != iCurNetwInBlSiFact )
                    {
                        // re-initialize to new value
                        SetNetwInBlSiFact ( iNewNetwInBlSiFact );
                    }
                }
            }

            // only process if packet has correct size
            if ( bIsAudioPacket )
            {
                Mutex.lock();
                {
                    // decompress audio
                    CVector<short> vecsDecomprAudio ( AudioCompressionIn.Decode ( vecbyData ) );

                    // do resampling to compensate for sample rate offsets in the
                    // different sound cards of the clients
/*
for (int i = 0; i < BLOCK_SIZE_SAMPLES; i++)
    vecdResInData[i] = (double) vecsData[i];

const int iInSize = ResampleObj.Resample(vecdResInData, vecdResOutData,
    (double) SERVER_SAMPLE_RATE / (SERVER_SAMPLE_RATE - dSamRateOffset));
*/

vecdResOutData.Init ( iCurNetwInBlSiFact * MIN_BLOCK_SIZE_SAMPLES );
for ( int i = 0; i < iCurNetwInBlSiFact * MIN_BLOCK_SIZE_SAMPLES; i++ ) {
    vecdResOutData[i] = (double) vecsDecomprAudio[i];
}

                    if ( SockBuf.Put ( vecdResOutData ) )
                    {
                        eRet = PS_AUDIO_OK;
                    }
                    else
                    {
                        eRet = PS_AUDIO_ERR;
                    }

                    // check if channel was not connected, this is a new connection
                    bNewConnection = !IsConnected();

                    // reset time-out counter
                    iConTimeOut = iConTimeOutStartVal;
                }
                Mutex.unlock();
            }
            else
            {
                // the protocol parsing failed and this was no audio block,
                // we treat this as protocol error (unkown packet)
                eRet = PS_PROT_ERR;

                // create message for protocol status
                emit ProtocolStatus ( false );
            }
        }

        // inform other objects that new connection was established
        if ( bNewConnection )
        {
            // log new connection
            CHostAddress address ( GetAddress() );
            qDebug() << CLogTimeDate::toString() + "Connected with IP " + address.InetAddr.toString();

            emit NewConnection();
        }
    }

    return eRet;
}

EGetDataStat CChannel::GetData ( CVector<double>& vecdData )
{
    // init with ok flag
    EGetDataStat eGetStatus = GS_BUFFER_OK;

    Mutex.lock(); // get mutex lock
    {
        if ( !SockBuf.Get ( vecdData ) )
        {
            // decrease time-out counter
            if ( iConTimeOut > 0 )
            {
                iConTimeOut--;

                if ( iConTimeOut == 0 )
                {
                    // channel is just disconnected
                    eGetStatus = GS_CHAN_NOW_DISCONNECTED;
                }
                else
                {
                    // channel is not yet disconnected but no data in buffer
                    eGetStatus = GS_BUFFER_UNDERRUN;
                }
            }
            else
            {
                // channel is disconnected
                eGetStatus = GS_CHAN_NOT_CONNECTED;
            }
        }
    }
    Mutex.unlock(); // get mutex unlock

    return eGetStatus;
}

CVector<unsigned char> CChannel::PrepSendPacket ( const CVector<short>& vecsNPacket )
{
    // if the block is not ready we have to initialize with zero length to
    // tell the following network send routine that nothing should be sent
    CVector<unsigned char> vecbySendBuf ( 0 );

    // use conversion buffer to convert sound card block size in network
    // block size
    if ( ConvBuf.Put ( vecsNPacket ) )
    {
        // a packet is ready, compress audio
        vecbySendBuf.Init ( iAudComprSizeOut );
        vecbySendBuf = AudioCompressionOut.Encode ( ConvBuf.Get() );
    }

    return vecbySendBuf;
}









/******************************************************************************\
* CSampleOffsetEst                                                             *
\******************************************************************************/
void CSampleOffsetEst::Init()
{
    /* init sample rate estimation */
    dSamRateEst = SERVER_SAMPLE_RATE;

    /* init vectors storing the data */
    veciTimeElapsed.Init(VEC_LEN_SAM_OFFS_EST);
    veciTiStIdx.Init(VEC_LEN_SAM_OFFS_EST);

    /* start reference time (the counter wraps to zero 24 hours after the last
       call to start() or restart, but this should not concern us since this
       software will most probably not be used that long) */
    RefTime.start();

    /* init accumulated time stamp variable */
    iAccTiStVal = 0;

    /* init count (do not ship any result in init phase) */
    iInitCnt = VEC_LEN_SAM_OFFS_EST + 1;
}

void CSampleOffsetEst::AddTimeStampIdx(const int iTimeStampIdx)
{
    int i;

    const int iLastIdx = VEC_LEN_SAM_OFFS_EST - 1;

    /* take care of wrap of the time stamp index (byte wrap) */
    if (iTimeStampIdx < veciTiStIdx[iLastIdx] - iAccTiStVal)
        iAccTiStVal += _MAXBYTE + 1;

    /* add new data pair to the FIFO */
    for (i = 1; i < VEC_LEN_SAM_OFFS_EST; i++)
    {
        /* move old data */
        veciTimeElapsed[i - 1] = veciTimeElapsed[i];
        veciTiStIdx[i - 1] = veciTiStIdx[i];
    }

    /* add new data */
    veciTimeElapsed[iLastIdx] = RefTime.elapsed();
    veciTiStIdx[iLastIdx] = iAccTiStVal + iTimeStampIdx;

/*
static FILE* pFile = fopen("v.dat", "w");
for (i = 0; i < VEC_LEN_SAM_OFFS_EST; i++)
    fprintf(pFile, "%d\n", veciTimeElapsed[i]);
fflush(pFile);
*/


    /* calculate linear regression for sample rate estimation */
    /* first, calculate averages */
    double dTimeAv = 0;
    double dTiStAv = 0;
    for (i = 0; i < VEC_LEN_SAM_OFFS_EST; i++)
    {
        dTimeAv += veciTimeElapsed[i];
        dTiStAv += veciTiStIdx[i];
    }
    dTimeAv /= VEC_LEN_SAM_OFFS_EST;
    dTiStAv /= VEC_LEN_SAM_OFFS_EST;

    /* calculate gradient */
    double dNom = 0;
    double dDenom = 0;
    for (i = 0; i < VEC_LEN_SAM_OFFS_EST; i++)
    {
        const double dCurTimeNoAv = veciTimeElapsed[i] - dTimeAv;
        dNom += dCurTimeNoAv * (veciTiStIdx[i] - dTiStAv);
        dDenom += dCurTimeNoAv * dCurTimeNoAv;
    }

    /* final sample rate offset estimation calculation */
    if (iInitCnt > 0)
        iInitCnt--;
    else
    {
        dSamRateEst = dNom / dDenom * NUM_BL_TIME_STAMPS * MIN_BLOCK_SIZE_SAMPLES * 1000;

/*
static FILE* pFile = fopen("v.dat", "w");
for (i = 0; i < VEC_LEN_SAM_OFFS_EST; i++)
    fprintf(pFile, "%d %d\n", veciTimeElapsed[i], veciTiStIdx[i]);
fflush(pFile);
*/
    }

/*
static FILE* pFile = fopen("v.dat", "w");
fprintf(pFile, "%e\n", dSamRateEst);
fflush(pFile);
*/

}