Here is an example of a Raspistill command for a constant stream of jpeg images:-
$ raspistill -w 640 -h 480 -q 5 -o /tmp/stream/pic.jpg -tl 100 -t 9999999 -th 0:0:0 &
Now let’s take a look at the arguments for Raspistill one by one:-
-w sets the image width. For an HD stream use 1920 here.
-h sets the image height. For an HD stream use 1080 here.
-q sets the JPEG quality level, from 0 to 100. I use a pretty low quality, better quality generates bigger pictures, which reduces the frame rate.
-o sets the output filename for the JPEG pictures. I’m sending them to a temp directory. The same file will be rewritten with updated pictures.
-tl sets the timelapse interval, in milliseconds. With a value of 100 you get 10 frames per second.
-t sets the time the program will run. I put a large number here, that amounts to about two hours of run time.
-th sets the thumbnail picture options. Since I want the pictures to be as small as possible I disabled the thumbnails by setting everything to zero.
& puts the application to run in the background.
If you are interested in setting up a stream from your Raspberry Pi camera to web browsers or even iOS or Android devices please visit this link for more details. http://blog.miguelgrinberg.com/post/stream-video-from-the-raspberry-pi-camera-to-web-browsers-even-on-ios-and-android