Calculating hashes for video files as used by MythTV in the DB table videometadata

mythhash.cpp

// on Debian/Ubuntu:
// - install libqt4-dev
// - put file into a directory called mythhash
// - run:
//        qmake -project
//        qmake
//        make

// C++ headers
#include <iostream>

using namespace std;

// Qt headers
#include <QtCore>
#include <QDataStream>
#include <QFileInfo>
#include <QFile>
#include <QDebug>

QString FileHash(QString filename)
{
    QFile file(filename);
    QFileInfo fileinfo(file);
    qint64 initialsize = fileinfo.size();
    quint64 hash = 0;

    if (initialsize == 0)
        return QString("NULL");

    if (file.open(QIODevice::ReadOnly))
        hash = initialsize;
    else
    {
        return QString("NULL");
    }

    file.seek(0);
    QDataStream stream(&file);
    stream.setByteOrder(QDataStream::LittleEndian);
    for (quint64 tmp = 0, i = 0; i < 65536/sizeof(tmp); i++)
    {
        stream >> tmp;
        hash += tmp;
    }

    file.seek(initialsize - 65536);
    for (quint64 tmp = 0, i = 0; i < 65536/sizeof(tmp); i++)
    {
        stream >> tmp;
        hash += tmp;
    }

    file.close();

    QString output = QString("%1").arg(hash, 0, 16);
    return output;
}

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    if (argc == 1) {
        std::cout << "Usage: mythhash <file>" << std::endl;
        exit(1);
    } else {
        QString filename = QString::fromUtf8(argv[1]);
        QString filehash = FileHash(filename);
        std::string utf8_text = filehash.toUtf8().constData();
        std::cout << utf8_text << std::endl;
        exit(0);
    }
}
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