Question

我正在寻找一种方法来加密视频文件，然后使用它解密并直接播放。

Answer 1

setMedia将QIOdevice作为第二个参数：

  #include <QMediaPlayer>
  #include <QApplication>
  #include <QFile>
  int main(int argc, char ** argv)
  {
      QApplication app(argc,argv);
      QString fileName = app.arguments().at(1);

      QFile io(fileName);
      io.open(QFile::ReadOnly);

      QMediaPlayer player;

      player.setMedia(QUrl("test.mp3"), &io);
      player.play();

      return app.exec();
  }

但是，如果你真的意味着QDataStream：

QDataStream是缓冲io，QIODevice是直接io，它们不兼容，所以你必须像这样加倍缓冲：

#include <QMediaPlayer>
#include <QApplication>
#include <QFile>
#include <QBuffer>
#include <QDataStream>
int main(int argc, char ** argv)
{
    QApplication app(argc,argv);
    QString fileName = app.arguments().at(1);

    // our double buffer
    QByteArray bufferSpace;

    // our stream on which we can put "media" data
    QDataStream stream(&bufferSpace, QIODevice::WriteOnly);

    // this is just demo data
    QFile io(fileName);
    io.open(QFile::ReadOnly);
    stream << io.readAll();

    // open an IO Device on our buffer
    QBuffer buffer(&bufferSpace);
    buffer.open(QBuffer::ReadOnly);

    // give the IO to the media player
    QMediaPlayer player;
    player.setMedia(QUrl("test.mp3"), &buffer);
    player.play();

    return app.exec();
}

修改

这是您发布的“加密”代码的更快版本，而不使用整个文件的缓冲区：

#include <QMediaPlayer> #include <QApplication> #include <QFile> #include <QBuffer> #include <QDataStream> static const unsigned char key = 0xAB; class MyFunnyCrypto : public QFile /*or subclass any other IO*/ { protected: virtual qint64 readData(char *data, qint64 maxSize) { qint64 r = QFile::readData(data, maxSize); if (r > 0) { for (qint64 i = 0; i < r; i++) { data[i] = data[i]^key; } } return r; } }; int main(int argc, char ** argv) { QApplication app(argc,argv); QString fileName = app.arguments().at(1); MyFunnyCrypto io; io.setFileName(fileName); io.open(QFile::ReadOnly); // give the IO to the media player QMediaPlayer player; player.setMedia(QUrl("test.mp3"), &io); player.play(); return app.exec(); }

Answer 2

感谢@aep。它与QDataStream没有任何关系，而且非常简单。加密：

unsigned char key = 0xAB;
QFile file("test.mp3");
file.open(QIODevice::ReadOnly);
QByteArray byteArray = file.readAll();
for(int i=1024;i<byteArray.length();i++){
    byteArray[i] = byteArray[i]^key;
}
file.close();

QFile encrypted("encrypted.mp3");
encrypted.open(QIODevice::WriteOnly);
encrypted.write(byteArray);
encrypted.close();

解密：

unsigned char key = 0xAB;
QFile file("encrypted.mp3");
file.open(QIODevice::ReadOnly);
auto byteArray = file.readAll();
for(int i=1024;i<byteArray.length();i++){
     byteArray[i] = byteArray[i]^key;
}

QBuffer buffer(&byteArray);
buffer.open(QBuffer::ReadOnly);

// give the IO to the media player
QMediaPlayer player;
player.setMedia(QUrl(), &buffer);
player.play();

在for循环中，我想将i声明为qint64而不是int。但编译器显示QByteArray::operator[](int i)。

如何使用Qt加密/解密/播放视频？

2 个答案: