java.lang.RuntimeException: takePicture failed

Firstly, catch your exceptions in onPictureTaken, leaving empty catch sections is not a good practice. Then, I would add a flag that would prevent from calling takePicture() while previous picture is being saved. Later in your button onClick you would check if it’s ok to call takePicture().

1. Declare a flag as a member of your Activity:

   private boolean safeToTakePicture = false;
   

2. In surfaceChanged(), just set the flag to true after calling startPreview():

   camera.startPreview();
   safeToTakePicture = true;
   

3. In your onClick() listener check the flag and take picture if ok to do so:

   if (safeToTakePicture) {
       mp.start();
       camera.takePicture(null, null, mPicture); 
       safeToTakePicture = false;
   }
   

4. In onPictureTaken(), set the flag again to true after picture has been saved (and add exception printing):

   PictureCallback mPicture = new PictureCallback() {
       @Override
       public void onPictureTaken(byte[] data, Camera camera) {
           pictureFile = getOutputMediaFile();
           camera.startPreview();
   
           if (pictureFile == null) {
               //no path to picture, return
               safeToTakePicture = true;
               return;
           }
           try {
               FileOutputStream fos = new FileOutputStream(pictureFile);
               fos.write(data);
               fos.close();
   
           } catch (FileNotFoundException e) {
               e.printStackTrace();              //<-------- show exception
           } catch (IOException e) {
               e.printStackTrace();              //<-------- show exception
           }
   
           //finished saving picture 
           safeToTakePicture = true;
       }
   };
   

NOTES:
As the docs say, “Preview must be started before you can take a picture.”, so possible enhancement would be to use setPreviewCallback() to register callback that will be called when preview data is available, and set the flag to true when onPreviewFrame is called.