Using the Application Class
Depending on what you're doing in your initialization you could consider creating a new class that extends Application and moving your initialization code into an overridden onCreate method within that class.
public class MyApplicationClass extends Application {
@Override
public void onCreate() {
super.onCreate();
// TODO Put your application initialization code here.
}
}
The onCreate in the application class is only called when the entire application is created, so the Activity restarts on orientation or keyboard visibility changes won't trigger it.
It's good practice to expose the instance of this class as a singleton and exposing the application variables you're initializing using getters and setters.
NOTE: You'll need to specify the name of your new Application class in the manifest for it to be registered and used:
<application
android:name="com.you.yourapp.MyApplicationClass"
Reacting to Configuration Changes [UPDATE: this is deprecated since API 13; see the recommended alternative]
As a further alternative, you can have your application listen for events that would cause a restart – like orientation and keyboard visibility changes – and handle them within your Activity.
Start by adding the android:configChanges node to your Activity's manifest node
<activity android:name=".MyActivity"
android:configChanges="orientation|keyboardHidden"
android:label="@string/app_name">
or for Android 3.2 (API level 13) and newer:
<activity android:name=".MyActivity"
android:configChanges="keyboardHidden|orientation|screenSize"
android:label="@string/app_name">
Then within the Activity override the onConfigurationChanged method and call setContentView to force the GUI layout to be re-done in the new orientation.
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
setContentView(R.layout.myLayout);
}
Rotate 90 clockwise:
ffmpeg -i in.mov -vf "transpose=1" out.mov
For the transpose parameter you can pass:
0 = 90CounterCLockwise and Vertical Flip (default)
1 = 90Clockwise
2 = 90CounterClockwise
3 = 90Clockwise and Vertical Flip
Use -vf "transpose=2,transpose=2" for 180 degrees.
Make sure you use a recent ffmpeg version from here (a static build will work fine).
Note that this will re-encode the audio and video parts. You can usually copy the audio without touching it, by using -c:a copy. To change the video quality, set the bitrate (for example with -b:v 1M) or have a look at the H.264 encoding guide if you want VBR options.
A solution is also to use this convenience script.
Best Answer
A quaternion has 4 components, which can be related to an angle θ and an axis vector n. The rotation will make the object rotate about the axis n by an angle θ.
For example, if we have an cube like
Then a rotation of 90° about the axis (x=0, y=0, z=1) will rotate the "5" face from the left to the front.
(Note: This is the axis/angle description of rotation, which is what OP confuses. For how quaternion is applied to rotation, see http://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation)