we can define a video as a succession of n frames in time which can be seen as another dimension, n is the frame rate or frames per second (FPS).

bit rate = width * height * bit depth * frames per second

video codecs

piece of software hardware that compresses or decompresses digital video

generic codec

1. picture partitioning - divide the frame into several partitions, sub-partitions and beyond
2. predictions inter /intra
3. transform - after we get residual block , we can transform it in a way that lets us know which pixels we can discard while keeping the overall quality

he DCT main features are:

• converts blocks of pixels into same-sized blocks of frequency coefficients.
• compacts energy, making it easy to eliminate spatial redundancy.
• is reversible, a.k.a. you can reverse to pixels.

in am image most of the energy will be concentrated in the lower frequencies ,so if we transform an image into its frequency components and throw away the higher frequency coefficients we can reduce the amount of data needed to describe the image without sacrificing too much image quality

1. quantization - lose information - we quantize coefficients to achieve compression . we use matrix of quantizers

1. entropy coding - after quantization we still can compress it in a lossless way ,

   vlc coding

2. bitstream format