source:
http://www.raspberrypi-spy.co.uk/2013/05/creating-timelapse-videos-with-the-raspberry-pi-camera/

Step 1 – Taking the time-lapsed photos

This command will take a photo every 60 seconds (60000 milliseconds) for 2 hours (7200000 milliseconds) resulting in a sequence of 120 images.

raspistill -o timelapse_%04d.jpg -tl 60000 -t 7200000

The “%04d” will result in a four digit number appearing in each filename.

myimage_0001.jpg
myimage_0002.jpg

myimage_0119.jpg
myimage_0120.jpg

Step 2 – Combine images into MP4 video

Once you’ve got your image sequence you will need a method to stitch them together. I decided to use “avconv”. You can install this useful library with the following command :

sudo apt-get -y install libav-tools

To construct the video file from your image sequence you use the command shown below. Although it appears on multiple lines for readability it should be entered as a single line on the command line :

avconv -r 10 -i timelapse_%04d.jpg -r 10 -vcodec libx264 -crf 20 -g 15 timelapse.mp4

The video will be the full resolution of the default image size (2592×1944).

To crop the images and create a more standard 1280×720 resolution video you can use the following command :

avconv -r 10 -i timelapse_%04d.jpg -r 10 -vcodec libx264 -crf 20 -g 15 -vf crop=2592:1458,scale=1280:720 timelapse.mp4

The “vf” option defines a video filter. In this case two filters which crop the incoming image to 2592×1458 and then scale them to 1280×720.

The “r” option tells avconv to create a video with a frames per second of 10. It appears twice to prevent avconv dropping frames that it thinks are similar.

The “crf” option tells avconv to aim for a quality level of “20″ which is a good starting point. Lowers values are better but will increase the file size.

The “-g” option sets the GOP value. The YouTube Advanced Encoding Settings page recommends that the GOP should be set to half the frame rate so this is set to 15.