Kwave::PlayBackQt::Buffer Class Reference

Inheritance diagram for Kwave::PlayBackQt::Buffer:

Collaboration diagram for Kwave::PlayBackQt::Buffer:

Public Member Functions
	Buffer ()
virtual	~Buffer () Q_DECL_OVERRIDE
void	start (unsigned int buf_size, int timeout)
void	setTimeout (int timeout)
void	drain (QByteArray &padding)
void	stop ()
virtual qint64	readData (char *data, qint64 len) Q_DECL_OVERRIDE
virtual qint64	writeData (const char *data, qint64 len) Q_DECL_OVERRIDE
virtual qint64	bytesAvailable () const Q_DECL_OVERRIDE

Private Attributes
QMutex	m_lock
QSemaphore	m_sem_free
QSemaphore	m_sem_filled
QQueue< char >	m_raw_buffer
int	m_timeout
QByteArray	m_pad_data
int	m_pad_ofs

Detailed Description

Definition at line 140 of file PlayBack-Qt.h.

Constructor & Destructor Documentation

Buffer()

Kwave::PlayBackQt::Buffer::Buffer

(

)

constructor

Definition at line 464 of file PlayBack-Qt.cpp.

    :QIODevice(),
     m_lock(QMutex::Recursive),
     m_sem_free(0),
     m_sem_filled(0),
     m_raw_buffer(),
     m_timeout(1000),
     m_pad_data(),
     m_pad_ofs(0)
{
}

~Buffer()

Kwave::PlayBackQt::Buffer::~Buffer ( )

virtual

destructor

Definition at line 477 of file PlayBack-Qt.cpp.

{
}

Member Function Documentation

bytesAvailable()

qint64 Kwave::PlayBackQt::Buffer::bytesAvailable ( ) const

virtual

returns the number of bytes available for reading

Definition at line 584 of file PlayBack-Qt.cpp.

References m_pad_data, m_pad_ofs, and m_sem_filled.

Referenced by Kwave::PlayBackQt::close().

{
    return QIODevice::bytesAvailable() +
           m_sem_filled.available() +
           m_pad_data.size() -
           m_pad_ofs;
}

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drain()

void Kwave::PlayBackQt::Buffer::drain

(

QByteArray &

padding

)

drain the sink, at the end of playback: provide padding to provide data for a full period

Parameters

padding

array of bytes used for padding

Definition at line 504 of file PlayBack-Qt.cpp.

References m_pad_data, and m_pad_ofs.

Referenced by Kwave::PlayBackQt::close().

{
    m_pad_data = padding;
    m_pad_ofs  = 0;
}

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readData()

qint64 Kwave::PlayBackQt::Buffer::readData ( char *  data, qint64  len  )

virtual

read data out from the buffer, called from the Qt audio device side

Parameters

data	pointer to a buffer (of bytes) to receive the data
len	number of bytes to read

Returns

number of bytes that have been read

Definition at line 517 of file PlayBack-Qt.cpp.

References m_lock, m_pad_data, m_pad_ofs, m_raw_buffer, m_sem_filled, m_sem_free, m_timeout, and Kwave::toInt().

{
    qint64 read_bytes = -1;
    qint64 requested  = len;

//     qDebug("Kwave::PlayBackQt::Buffer::readData(..., len=%lld", requested);
    if (len == 0) return  0;
    if (len  < 0) return -1;

    while (len > 0) {
        int count = qMin<int>(
            qMax(m_sem_filled.available(), 1),
            Kwave::toInt(len)
        );
        if (Q_LIKELY(m_sem_filled.tryAcquire(count, m_timeout))) {
//          qDebug("    read: locking...");
            QMutexLocker _lock(&m_lock); // context: qt streaming engine
//          qDebug("    read: locked, count=%lld", len);
            m_sem_free.release(count);
            if (read_bytes < 0) read_bytes = 0;
            read_bytes += count;
            len        -= count;
            while (count--)
                *(data++) = m_raw_buffer.dequeue();
        } else break;
    }

    // if we are at the end of the stream: do some padding to satisfy Qt
    while ( (read_bytes < requested) &&
            !m_pad_data.isEmpty() && (m_pad_ofs < m_pad_data.size()) )
    {
        *(data++) = 0;
        read_bytes++;
        m_pad_ofs++;
    }

    if (read_bytes != requested)
        qDebug("Kwave::PlayBackQt::Buffer::readData(...) -> read=%lld/%lld",
               read_bytes, requested);

    return read_bytes;
}

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setTimeout()

void Kwave::PlayBackQt::Buffer::setTimeout

(

int

timeout

)

set a new read/write timeout

Note

does not influence currently waiting reads/writes

Parameters

timeout

a new read/write timeout [ms]

Definition at line 496 of file PlayBack-Qt.cpp.

References m_lock, and m_timeout.

Referenced by Kwave::PlayBackQt::open().

{
    QMutexLocker _lock(&m_lock); // context: main thread
    m_timeout = timeout;
    qDebug("Kwave::PlayBackQt::Buffer::setTimeout(%d)", timeout);
}

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start()

void Kwave::PlayBackQt::Buffer::start	(	unsigned int	buf_size,
		int	timeout
	)

start filling the buffer

Parameters

buf_size	size of the buffer in bytes
timeout	read/write timeout [ms]

Definition at line 482 of file PlayBack-Qt.cpp.

References m_pad_data, m_pad_ofs, m_raw_buffer, m_sem_filled, m_sem_free, m_timeout, and Kwave::PlayBackQt::open().

Referenced by Kwave::PlayBackQt::open().

{
    m_raw_buffer.clear();
    m_sem_filled.acquire(m_sem_filled.available());
    m_sem_free.acquire(m_sem_free.available());
    m_sem_free.release(buf_size);
    m_timeout = timeout;
    m_pad_data.clear();
    m_pad_ofs = 0;

    open(QIODevice::ReadOnly);
}

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stop()

void Kwave::PlayBackQt::Buffer::stop

(

)

stop filling the buffer

Definition at line 511 of file PlayBack-Qt.cpp.

References Kwave::PlayBackQt::close().

Referenced by Kwave::PlayBackQt::close().

{
    close();
}

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writeData()

qint64 Kwave::PlayBackQt::Buffer::writeData ( const char *  data, qint64  len  )

virtual

write data into the buffer, called from our own worker thread

Parameters

data	pointer to a buffer (of bytes) to write
len	number of bytes to write

Returns

number of bytes written

Definition at line 561 of file PlayBack-Qt.cpp.

References m_lock, m_raw_buffer, m_sem_filled, m_sem_free, m_timeout, and Kwave::toInt().

Referenced by Kwave::PlayBackQt::write().

{

    qint64 written_bytes = 0;
    while (len) {
        int count = qMin<int>(
            qMax(m_sem_free.available(), 1),
            Kwave::toInt(len)
        );
        if (Q_LIKELY(m_sem_free.tryAcquire(count, m_timeout * 10))) {
            QMutexLocker _lock(&m_lock); // context: kwave worker thread
            m_sem_filled.release(count);
            written_bytes += count;
            len           -= count;
            while (count--)
                m_raw_buffer.enqueue(*(data++));
        } else break;
    }

    return written_bytes;
}

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Member Data Documentation

m_lock

QMutex Kwave::PlayBackQt::Buffer::m_lock

private

mutex for locking the queue

Definition at line 197 of file PlayBack-Qt.h.

Referenced by readData(), setTimeout(), and writeData().

m_pad_data

QByteArray Kwave::PlayBackQt::Buffer::m_pad_data

private

buffer with padding data

Definition at line 212 of file PlayBack-Qt.h.

Referenced by bytesAvailable(), drain(), readData(), and start().

m_pad_ofs

int Kwave::PlayBackQt::Buffer::m_pad_ofs

private

read pointer within m_pad_data

Definition at line 215 of file PlayBack-Qt.h.

Referenced by bytesAvailable(), drain(), readData(), and start().

m_raw_buffer

QQueue<char> Kwave::PlayBackQt::Buffer::m_raw_buffer

private

raw buffer with audio data

Definition at line 206 of file PlayBack-Qt.h.

Referenced by readData(), start(), and writeData().

m_sem_filled

QSemaphore Kwave::PlayBackQt::Buffer::m_sem_filled

private

semaphore with filled buffer space

Definition at line 203 of file PlayBack-Qt.h.

Referenced by bytesAvailable(), readData(), start(), and writeData().

m_sem_free

QSemaphore Kwave::PlayBackQt::Buffer::m_sem_free

private

semaphore with free buffer space

Definition at line 200 of file PlayBack-Qt.h.

Referenced by readData(), start(), and writeData().

m_timeout

int Kwave::PlayBackQt::Buffer::m_timeout

private

read timeout [ms]

Definition at line 209 of file PlayBack-Qt.h.

Referenced by readData(), setTimeout(), start(), and writeData().

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The documentation for this class was generated from the following files:

• plugins/playback/PlayBack-Qt.h
• plugins/playback/PlayBack-Qt.cpp