readaheadvideobuffer.h

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/*                       
        This file is part of the CVD Library.

        Copyright (C) 2005 The Authors

        This library is free software; you can redistribute it and/or
        modify it under the terms of the GNU Lesser General Public
        License as published by the Free Software Foundation; either
        version 2.1 of the License, or (at your option) any later version.

        This library 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
        Lesser General Public License for more details.

        You should have received a copy of the GNU Lesser General Public
        License along with this library; if not, write to the Free Software
        Foundation, Inc., 
    51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#ifndef CVD_READAHEADVIDEOBUFFER_H
#define CVD_READAHEADVIDEOBUFFER_H

#include <cvd/config.h>
#include <cvd/videobuffer.h>

#ifdef CVD_HAVE_PTHREAD
#include <deque>
#include <cvd/thread.h>
#include <cvd/synchronized.h>
#include <cvd/eventobject.h>
#endif

namespace CVD {
    #ifndef CVD_HAVE_PTHREAD
    #warning ReadAheadVideoBuffer will not do any read-ahead because threads are not supported in this build
    template <class T> 
    class ReadAheadVideoBuffer : public VideoBuffer<T>
    {
    private:
        VideoBuffer<T>& vbuffer;
    public:
        virtual ~ReadAheadVideoBuffer() {}
        ReadAheadVideoBuffer(VideoBuffer<T>& vb, size_t maxReadAhead=10) 
        : VideoBuffer<T>(vb.type()),vbuffer(vb) {}
        ImageRef size() { return vbuffer.size(); }
        VideoFrame<T>* get_frame() { return vbuffer.get_frame(); }
        void put_frame(VideoFrame<T>* f) { vbuffer.put_frame(f); }
        bool frame_pending() { return vbuffer.frame_pending(); }
        double frame_rate() { return vbuffer.frame_rate(); }
        void seek_to(double t){ vbuffer.seek_to(t); }
    };
#else    






    template <class T> 
    class ReadAheadVideoBuffer : public VideoBuffer<T>, public Runnable
    {
    private:
        VideoBuffer<T>& vbuffer;
        size_t maxRA;
        std::deque<VideoFrame<T>*> q, putq;
        Synchronized vblock;
        EventObject qevent;
        Thread thread;


        static VideoBufferType::Type type_update(VideoBufferType::Type t)
        {
                if(t== VideoBufferType::NotLive)
                        return t; 
                else
                        return VideoBufferType::Flushable;
        }

    public:
        virtual ~ReadAheadVideoBuffer() {
            qevent.lock();
            thread.stop();
            qevent.trigger();
            qevent.unlock();
            thread.join();          
        }
        ReadAheadVideoBuffer(VideoBuffer<T>& vb, size_t maxReadAhead=10) 
        : VideoBuffer<T>(type_update(vb.type())), vbuffer(vb), maxRA(maxReadAhead) {
            thread.start(this);     
        }

        void run() {
            while (!thread.shouldStop()) 
            {
                // lock queue
                { Lock l(qevent);
                    for (size_t i=0; i<putq.size(); i++)
                        vbuffer.put_frame(putq[i]);
                    putq.resize(0);
                    while (q.size() >= maxRA) {             
                        qevent.wait();
                        if (thread.shouldStop())
                            return;
                    }
                }
                // lock videobuffer
                { Lock l(vblock);
                    VideoFrame<T>* frame = vbuffer.get_frame();
                    // lock queue
                    { Lock l(qevent);
                        q.push_back(frame);
                        qevent.trigger();
                    }
                }
            }
        }
        ImageRef size() { return vbuffer.size(); }
        VideoFrame<T>* get_frame() {
            VideoFrame<T>* frame = 0;
            Lock l(qevent);
            while (q.empty())
                qevent.wait();
            frame = q.front();
            q.pop_front();
            qevent.trigger(); 
            return frame;
        }
        void put_frame(VideoFrame<T>* f) { Lock l(qevent); putq.push_back(f); }
        bool frame_pending() {
            return !q.empty();
        }
        double frame_rate() { return vbuffer.frame_rate(); }
        void seek_to(double t){
            Lock vbl(vblock);
            Lock ql(qevent);
            for (size_t i=0; i<q.size(); i++)
                putq.push_back(q[i]);
            q.resize(0);
            qevent.triggerAll();
            vbuffer.seek_to(t);
        }
    };
    #endif
}

#endif

---

libcvd
Author(s): Edward Rosten, Paul Smith, Tom Drummond, Gerhard Reitmayr, Ethan Eade, Timothy Gan, Chris Kemp, Georg Klein
autogenerated on Fri Jan 11 09:13:10 2013