ClipWorkflow.h 7.88 KB
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 /*****************************************************************************
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 * ClipWorkflow.h : Clip workflow. Will extract a single frame from a VLCMedia
 *****************************************************************************
 * Copyright (C) 2008-2009 the VLMC team
 *
 * Authors: Hugo Beauzee-Luyssen <hugo@vlmc.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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

#ifndef CLIPWORKFLOW_H
#define CLIPWORKFLOW_H

#include <QReadWriteLock>
#include <QMutex>
#include <QObject>
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#include <QQueue>
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#include "Clip.h"
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#include "WaitCondition.hpp"
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#include "VLCMediaPlayer.h"
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#include "LightVideoFrame.h"
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class   ClipWorkflow : public QObject
{
    Q_OBJECT

    public:
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        enum        State
        {
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            None = -1,
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            /// \brief  Used when the clipworkflow hasn't been started yet
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            Stopped,        //0
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            /// \brief  Used when the clipworkflow is launched and active
            Rendering,      //1
            /// \brief  Used when stopping
            Stopping,       //2
            /// \brief  Used when end is reached, IE no more frame has to be rendered, but the trackworkflow
            ///         may eventually ask for some.
            EndReached,     //3
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            // Here starts internal states :
            /// \brief  This state will be used when an unpause
            ///         has been required
            UnpauseRequired,
            /// \brief  This state will be used when a pause
            ///         has been required
            PauseRequired,
            /// \brief  This state will be used when the media player is paused,
            ///         because of a sufficient number of computed buffers
            Paused,
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        };

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        /**
         *  \brief  Used to know which way you want to get a computed output.
         *          Pop: the buffer is popped and returned
         *          Get: the buffer is just returned (for paused mode for instance)
         */
        enum        GetMode
        {
            Pop,
            Get,
        };

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        ClipWorkflow( Clip* clip );
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        virtual ~ClipWorkflow();

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        /**
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         *  This method returns the current frame. It locks the renderMutex,
         *  therefore, you can call this method blindly, without taking care
         *  of the rendering process advancement.
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         */
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        virtual void*           getOutput( ClipWorkflow::GetMode mode ) = 0;
        void                    preGetOutput();
        void                    postGetOutput();
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        virtual void            initVlcOutput() = 0;
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        void                    initialize();
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        /**
         *  Return true ONLY if the state is equal to EndReached.
         *  In any other cases, this will return false.
         */
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        bool                    isEndReached() const;
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        /**
         *  Return true ONLY if the state is equal to Stopped.
         *  In any other cases, this will return false.
         */
        bool                    isStopped() const;

        /**
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         *  Return true ONLY if the state is equal to Rendering.
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         *  In any other cases, this will return false.
         */
        bool                    isRendering() const;

        /**
         *  Returns the current workflow state.
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         *  Be carrefull, as this function is NOT thread safe, and return the
         *  state without locking the state.
         *  It's your job to do it, by calling the getStateLock() method.
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         */
        State                   getState() const;

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        /**
            \brief              Returns the Clip this workflow instance is based
                                uppon, so that you can query information on it.
            \return             A pointer to a constant clip instance.
        */
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        Clip*                   getClip();
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        /**
            \brief  Stop this workflow.
        */
        void                    stop();
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        void                    setTime( qint64 time );
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        /**
         *  This method must be used to change the state of the ClipWorkflow
         *  from outside its render loop, otherwise, it may lead to deadlocks.
         *  No additional operations will be executed (for example, if setting
         *  the new state to stop, the media player won't be stopped.)
         *  This is mainly to change the behaviour of the render loop.
         */
        void                    queryStateChange( State newState );
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        /**
         *  This returns the QReadWriteLock that protects the ClipWorkflow's state.
         *  It should be use to lock the value when checking states from outside this
         *  class.
         */
        QReadWriteLock*         getStateLock();

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        void                    waitForCompleteInit();
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        virtual void*           getLockCallback() = 0;
        virtual void*           getUnlockCallback() = 0;

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        LibVLCpp::MediaPlayer*  getMediaPlayer();

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    private:
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        void                    setState( State state );
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        void                    adjustBegin();
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    protected:
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        void                    computePtsDiff( qint64 pts );
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        void                    commonUnlock();
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        virtual uint32_t        getAvailableBuffers() const = 0;
        virtual uint32_t        getComputedBuffers() const = 0;
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        virtual uint32_t        getMaxComputedBuffers() const = 0;
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    private:
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        LibVLCpp::MediaPlayer*  m_mediaPlayer;
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        State                   m_requiredState;
        QMutex*                 m_requiredStateLock;
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        WaitCondition*          m_initWaitCond;
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        WaitCondition*          m_pausingStateWaitCond;
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        /**
         *  While this flag is set to false, we will use the same buffer, to prevent
         *  having X buffers with the same picture (when media player is paused mainly)
         */
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        bool                    m_rendering;
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        /**
         *  This flag is here to avoid multiple connection to the mediaPlayer* slots.
         *  It's essentially a nasty hack due to the multiples calls to lock/unlock when
         *  the render is started, and that cannot really be avoided...
         */
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        bool                    m_initFlag;

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    protected:
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        Clip*                   m_clip;
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        QMutex*                 m_renderLock;
        QReadWriteLock*         m_stateLock;
        State                   m_state;
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        qint64                  m_previousPts;
        qint64                  m_currentPts;
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        /**
         *  \brief  The VLC media used to render
         */
        LibVLCpp::Media*        m_vlcMedia;
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        /**
         *  \brief  This is used for basic synchronisation when
         *          the clipworkflow hasn't generate a frame yet,
         *          while the renderer asks for one.
         */
        WaitCondition*          m_feedingCondWait;
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    protected:
        /**
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         *  \warning    Don't ever call this method from anywhere else than the unlock() method
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         */
        void                    checkStateChange();
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    private slots:
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        void                    loadingComplete();
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        void                    clipEndReached();
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        void                    mediaPlayerPaused();
        void                    mediaPlayerUnpaused();
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};

#endif // CLIPWORKFLOW_H