libccrtp-dev 2.0.9-2.2+b2 / usr / include / ccrtp / ioqueue.h

// Copyright (C) 2001,2002,2004 Federico Montesino Pouzols <fedemp@altern.org>.
//
// 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.
//
// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
//
// This exception applies only to the code released under the name GNU
// ccRTP.  If you copy code from other releases into a copy of GNU
// ccRTP, as the General Public License permits, the exception does
// not apply to the code that you add in this way.  To avoid misleading
// anyone as to the status of such modified files, you must delete
// this exception notice from them.
//
// If you write modifications of your own for GNU ccRTP, it is your choice
// whether to permit this exception to apply to your modifications.
// If you do not wish that, delete this exception notice.
//

/**
 * @file ioqueue.h
 *
 * @short Generic RTP input/output queues.
 **/

#ifndef CCXX_RTP_IOQUEUE_H_
#define CCXX_RTP_IOQUEUE_H_

#include <ccrtp/iqueue.h>
#include <ccrtp/oqueue.h>

NAMESPACE_COMMONCPP

/**
 * @defgroup ioqueue Generic RTP input/output queues.
 * @{
 **/

/**
 * @class RTPDataQueue
 *
 * A packet queue handler for building different kinds of RTP protocol
 * systems.  The queue manages both incoming and outgoing RTP packets,
 * as well as synchronization and transmission/reception timers.  By
 * making the queue handler a seperate base class it becomes possible
 * to define RTP classes for RTP profiles and sessions of different
 * types.
 *
 * Outgoing packets are sent via the OutgoingDataQueue::putData method.
 *
 * Incoming packets can be retrieved via IncomingDataQueue::getData
 * method.
 *
 * @author David Sugar <dyfet@ostel.com>
 * @short RTP data queue handler.
 */
class __EXPORT RTPDataQueue :
    public IncomingDataQueue,
    public OutgoingDataQueue
{
public:
    /**
     * @enum Tos rtp.h cc++/rtp.h
     * @short Type of network service the application uses.
     *
     * If the application uses enhanced network service, for
     * instance Integrated Services or Differentiated Services, it
     * <em>has not</em> to ensure fair competition with TCP,
     * provided that the requested service is actually being
     * delivered.  Whenever the application uses best-effort
     * service or the requested enhanced service is not actually
     * being delivered, it <em>has</em> to ensure fair competition
     * with TCP. By default, best-effot is assumed.
     *
     * @note Although not required, RTP packets are always sent on
     * top of UDP segments. No other underlying transport protocol
     * is supported at present.
     *
     * @todo implement fair competition with tcp
     **/
    typedef enum {
        tosBestEffort,      ///< Best-effort network service
        tosEnhanced         ///< Enhanced network service
    }       Tos;

    /**
     * Specify the kind of service the application expects to use.
     *
     * @param tos type of service the application expects to use
     *
     * @note If enhanced service is specified but packet loss is
     * high (the requested service does not appear to actually be
     * delivered) ccRTP defaults to best-effort suitable
     * behaviour: guarantee fair competition with TCP.
     *
     * @todo Implement fair competition with tcp
     **/
    inline void
    setTypeOfService(Tos tos)
    { typeOfService = tos; }

    /**
     * Enable packet queue processing in the stack. This method
     * will not any thread of execution.
     **/
    inline void enableStack()
    { dataServiceActive = true; }

        /**
         * Disable packet queue processing in the stack.
         **/
        inline void disableStack()
        { dataServiceActive = false; }

    /**
     * Get active connection state flag.
     *
     * @return true if connection "active".
     */
    inline bool
    isActive() const
    { return dataServiceActive; }

    /**
     * Get the timestamp that should be given for a packet whose
     * payload sampling instant corresponds to the current system
     * time.
     *
     * The timestamp applications should provide for each packet
     * represents the sampling instant of its payload and should
     * not be a reading of the system clock. Nevertheless, the
     * internal operation of the RTP stack relies on the accuracy
     * of the provided timestamp, since several computations
     * assume that there is a certain degree of correspondence
     * between the timestamp and the system clock.
     *
     * It is recommended that applications use this method in
     * order to <em>periodically adjust the RTP timestamp</em>.
     *
     * In particular, it is advisable getting the timestamp
     * corresponding to the first sampling instant or any instant
     * after a period of inactivity through a call to this method.
     *
     * Applications should use the nominal sampling or
     * any other value provided by the coder in order to compute
     * the next timestamps with minimum computational requirement.
     *
     * For instance, an application using an RTP profile that
     * specifies a fixed sampling rate of 8 Khz with eight bits
     * per sample, continuously transmitting audio blocks 80
     * octets long, would transmit 100 packets every
     * second. Every packet would carry a timestamp 80 units
     * greater than the previous one. So, the first timestamp
     * would be obtained from this method, whereas the following
     * ones would be computed adding 80 every time. Also the
     * timestamp should be increased for every block whether
     * it is put in the queue or dropped.
     *
     * The aforementioned increment can be obtained from the
     * RTPDataQueue::getTimestampIncrement() method rather than
     * computing it by hand in the application.
     *
     * @note Frame based applications must follow a specific
     * timestamping method, probably specified in a profile.
     *
     * @note You should take into account that by default ccRTP
     * assumes that the application begins sampling at the queue
     * creation time.  Moreover, the first sampling instant is
     * assigned a "user visible" timestamp of 0, although the RTP
     * stack will then add internally a ramdom offset unknown to
     * the application.  That is to say, the application may count
     * samples from 0 in order to get the timestamp for the next
     * packet, provided that the first sampling instant is the
     * same as the queue creation time.  Nevertheless, this
     * simpler way of starting will not be as accurate as it would
     * be if the application got at least the first timestamp
     * through getCurrentTimestamp.  <em>We provide this option
     * since ccRTP interface is evolving, but we admit that it is
     * ugly, we could remove this option or even replace uint32
     * timestamps with a restrictively regulated object;
     * suggestions are gladly welcomed</em>
     **/
    uint32
    getCurrentTimestamp() const;

    /**
     * Specify the bandwidth of the current session.
     *
     * @param bw bandwidth of the current session, in bits/s.
     *
     * @see AVPQueue::setControlBandwidth()
     */
    void
    setSessionBandwidth(uint32 bw)
    { sessionBw = bw; }

    uint32
    getDefaultSessionBandwidth() const
    { return defaultSessionBw; }

    uint32
    getSessionBandwidth() const
    { return sessionBw; }

    /**
     * Set the packet timeclock for synchronizing timestamps.
     **/
    inline void
    setTimeclock()
    { timeclock.setTimer(); }

    /**
     * Get the packet timeclock for synchronizing timestamps.
     *
     * @return runtime in milliseconds since last set.
     */
    inline timeout_t
    getTimeclock() const
    { return timeclock.getElapsed(); }

protected:

    /**
     * Constructor. This will generate a random application SSRC
     * identifier.
     *
     * @param size an estimation of the number of participants in
     * the session
     **/
    RTPDataQueue(uint32 size = defaultMembersHashSize);

    /**
     * Using this constructor you can start a session with the
     * given ssrc, instead of the usual randomly generated
     * one. This is necessary when you need to initiate several
     * sessions having the same SSRC identifier, for instance, to
     * implement layered encoding, in which case each layer is
     * managed through a different session but all sessions share
     * the same SSRC identifier.
     *
     * @warning This doesn't seem to be a good solution
     *
     * @param ssrc Synchronization SouRCe identifier for this session
     * @param size an estimation of the number of participants in the
     *        session
     */
    RTPDataQueue(uint32* ssrc, uint32 size = defaultMembersHashSize);

    /**
     * The queue destructor flushes the queue and stops all
     * services.
     */
    inline virtual
    ~RTPDataQueue()
    { endQueue(); }

        /**
         * A plugin point for timer tick driven events.
         */
        inline virtual void
    timerTick()
    { return; }

    void renewLocalSSRC()
        {IncomingDataQueue::renewLocalSSRC();}

private:
    RTPDataQueue(const RTPDataQueue &o);

    RTPDataQueue&
    operator=(const RTPDataQueue &o);

    /**
     * Global queue initialization.
     *
     * @param localSSRC local 32-bit SSRC identifier
     **/
    void
    initQueue();

protected:
    /**
     * This method ends the queue.
     */
    void
    endQueue();

    /**
     * This function is used to check for and schedule against
     * arriving packets based on the derived connection type.
     *
     * @return true if packet waiting for processing.
     * @param number of microseconds to wait.
     */
    virtual bool
    isPendingData(microtimeout_t timeout) = 0;

private:
    // true if connection "active"
    volatile bool dataServiceActive;
    Tos typeOfService;
    TimerPort timeclock;
    /* RTP session bandwidth control */
    static const uint32 defaultSessionBw;
    uint32 sessionBw;


};

/** @}*/ // ioqueue

END_NAMESPACE

#endif  //CCXX_RTP_IOQUEUE_H_

/** EMACS **
 * Local variables:
 * mode: c++
 * c-basic-offset: 8
 * End:
 */