Reducing the size of the file

How can we make video small enough to transmit over the internet ?
 
There are basically three things we can change:
 
First is the frame size of the picture. A standard television picture has 720 pixels across and 576 pixels down. That is a lot of data. If we make that picture smaller we can reduce the amount of data that has to be sent down the line.
 
The second thing we can change is the frame rate. Television pictures are sent 25 times per second to give a smooth video signal. Over the internet we can reduce this down to 12.5 or even 8 fps to give a slightly more jerky picture, but still maintain an acceptable video experience to the viewer.
 
The third thing we can change is picture compression. Just as Gifs and JPEGs are used to compress still images to transmit over the internet, streaming uses techniques to compress the picture for video and audio.
 
One of the things we can do differently is to only send the changes between one frame and the next frame or one picture and the next picture.
 
So there are three basic mechanisms to encode video:

• We can change the frame size
• We can change the frame rate
• We can do picture compression