User-level solutions for Android

Rotate video

You did not turn your phone 90 degrees and what’s worse, VLC player plays the vertical video as horizontal.

To fix this, you can rotate it on a Linux system with the following steps:

1. Install ffmpeg from https://launchpad.net/~mc3man/+archive/ubuntu/trusty-media:

   sudo add-apt-repository -y ppa:mc3man/trusty-media
   sudo apt-get update
   sudo apt-get install -y ffmpeg
   

2. Transform the video:

   # for clockwise
   ffmpeg -i in.mp4 -vf "transpose=1" out.mp4 
   # for counterclockwise
   ffmpeg -i in.mp4 -vf "transpose=2" out.mp4 
   

Developing with Android Studio

No R class generated from the resource files

This is because there are errors in your resource files. Make them error-free (e.g., by commenting the erroneous parts), then rebuild the project. Source: https://stackoverflow.com/questions/3462609/no-r-class-is-generated