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MPGStream.cpp

Go to the documentation of this file.

#include "MPGStream.hpp"

MPGStream::~MPGStream() {
    file.close();
}


MPGStream::MPGStream(const QString & fname, bool preRead,
                     uint numFrames):Stream(fname, preRead) {

    // open the file
    file.setName(fname);
    if (!file.open(IO_ReadOnly)) {
                cerr << "Can't open " << fname.ascii() << "!\n\n";
                exit(ERR_FILE);         // use exception here l8er
    }
#if MYDEBUG >= 4
    printf("MPGStream Constructor: opening \"%s\" as input file (%li bytes)\n",
               fname.data(), file.size());
#endif

    // set file to start position
    if (!file.at(0)) {
                cerr << "can't go to file position 0!";
                exit(-1);
    }
    fileSize = file.size();

    gopList.setAutoDelete(TRUE);
    noFrames = 0;
    lastReadFrame = NULL;
    lastRefFrame = NULL;

    // go through the header
    parseHeader();

    // now read all VOPs
    if (preRead)
                while (addNextGOP(numFrames) != NULL);
}


void MPGStream::parseHeader() {
    int ch;
    uint code = 0;

    do {
                ch = file.getch();
                code = (code << 8) | ch;
    } while ((ch != EOF) && (code != VOP_START_CODE));

#if MYDEBUG >= 4
    printf("[%i:0x%x] ", ch, code);
    printf("getHeader finished at file pos %li\n", file.at());
#endif

    this->headerSize = file.at();
}



bool MPGStream::fillHeaderBuffer() {

    if (!file.at(0)) {
                return false;
    }
    // resize the buffer now!
    if (!headerBuffer.resize(headerSize)) {
#if MYDEBUG >= 1
                cout << "Can't resize the buffer to " << headerSize << " bytes!\n";
#endif
                return false;
    }
    // fill it now!
    if (!file.readBlock(headerBuffer.data(), headerSize)) {
#if MYDEBUG >= 1
                cout << "Can't read " << headerSize << " bytes from stream!\n";
#endif
    }
    return true;
}


MPGFrame *MPGStream::getNextFrame() {
    int ch;
    uint code = 0;
    MPGFrame *frame;
    uint frsize = 4;
    uint frOffset;
    FrameType type = NN_VOP;

    if (file.atEnd())
        return NULL;

    frOffset = file.at() - 4;

    do {
                ch = file.getch();      
                if (frsize == 4) {
                type = (FrameType) (ch >> 6);
                if (type != 0 && type != 1 && type != 2)
                                wmsg(0, "Frame: " << noFrames << ", FrameType: " << type);
                }
                code = (code << 8) | ch;
                frsize++;
    } while (ch != EOF && code != VOP_START_CODE);

    frame = new MPGFrame(type, frsize);
    frame->setFileOffset(frOffset);
    frame->setByteSize(frsize);
    frame->setNoInStream(noFrames);

#if MYDEBUG >= 4
    printf("getNextFrame %i (%i,0x%x) from file pos %9li (of %li)",
           noFrames, ch, code, file.at(), fileSize);
    printf("[%s%9i]\n",
           (type == I_VOP) ? "I" : (type == P_VOP) ? "P" : (type ==
                                                            B_VOP) ? "B" :
           "U", frsize);
#endif

#if MYDEBUG == 3
    printf("%s",
           (type == I_VOP) ? "I" : (type == P_VOP) ? "P" : (type ==
                                                            B_VOP) ? "B" :
           "U");
#endif

    lastReadFrame = frame;
    noFrames++;
    return frame;
}


GOP *MPGStream::addNextGOP(uint numFrames) {
    MPGGOP *p;
    MPGFrame *frame;
    bool frameAligned;
    uint dispNoFrames;

    if ((p = (MPGGOP *) gopList.last()) != NULL) {
                frame = (MPGFrame *) p->getFrame(p->getFrameCount() - 1);
                ASSERT(frame != NULL);
                dispNoFrames = frame->getNoInDisplay() + 1;
    } else
                dispNoFrames = 0;

    frameAligned = (numFrames != 0);

#if MYDEBUG >= 4
    printf("MPGaddNextGOP from file pos %ld ", file.at());
    if (numFrames == 0)
                printf("\n");
    else
                printf("maxFrames: %i)\n", numFrames);
#endif

    if (file.atEnd())
                return NULL;

    p = new MPGGOP(this, gopList.count());

    // read until next I_VOP
    if (!frameAligned) {
                if (lastReadFrame != NULL) {
                lastReadFrame->setNoInGOP(p->getFrameCount());
                lastReadFrame->setNoInDisplay(dispNoFrames++);
                lastReadFrame->setGOP(p);
                p->addFrame(lastReadFrame);     // this was the old I_VOP
                }

                while ((frame = getNextFrame()) != NULL) {
                if ((noFrames > 1) && (frame->getType() == I_VOP)) {
                                break;
                }
                if (frame->getType() == B_VOP) {
                                frame->setNoInGOP(p->getFrameCount());
                                frame->setNoInDisplay(dispNoFrames++);
                                frame->setGOP(p);
                                p->incNoBVOPs();
                                //~ p->addBVOPsByteSize(frame->getByteSize());
                                p->addFrame(frame);
                } 
                        else {
                                if (lastRefFrame != NULL) {
                                lastRefFrame->setNoInGOP(p->getFrameCount());
                                lastReadFrame->setNoInDisplay(dispNoFrames++);
                                lastReadFrame->setGOP(p);
                                p->addFrame(lastRefFrame);
                                }
                                lastRefFrame = frame;
                }
                }
    }
    // frameAligned, ignore I_VOP patterns, 
    // break pattern down to frame rate (frames per second)
    else {
                while ((frame = getNextFrame()) != NULL) {
                if (frame->getType() == B_VOP) {
                                frame->setNoInGOP(p->getFrameCount());
                                frame->setNoInDisplay(dispNoFrames++);
                                frame->setGOP(p);
                                p->incNoBVOPs();
                                //~ p->addBVOPsByteSize(frame->getByteSize());
                                p->addFrame(frame);

                                if (--numFrames == 0)
                                break;
                } 
                        else {
                                if (lastRefFrame != NULL) {
                                lastRefFrame->setNoInGOP(p->getFrameCount());
                                lastRefFrame->setNoInDisplay(dispNoFrames++);
                                lastRefFrame->setGOP(p);
                                p->addFrame(lastRefFrame);
                                if (--numFrames == 0)
                                                break;
                                }
                                lastRefFrame = frame;
                }
                }
    }


#if MYDEBUG >= 3
    cout << " (" << gopList.count() << "|" << p->getFrameCount() << ")" << nl;
#endif
    p->calcByteSize();
    gopList.append(p);
    //  p->printInfo();
    return p;
}


long MPGStream::getFileSize() {
        return fileSize;
}


long MPGStream::getAvgFrameSize() {
        return fileSize / noFrames;
}


long MPGStream::getAvgGOPSize() {
        return fileSize / gopList.count();
}


uint MPGStream::getHeaderSize() {
        return headerSize;
}

char* MPGStream::getHeaderBuffer() {
        return headerBuffer.data();
}

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