A growing need has arisen for higher compression of video media for various applications such as videoconferencing, digital media storage, television broadcasting, internet video streaming and communication. Video, which comprises a sequence of images or “pictures,” undergoes compression during an encoding process performed by an encoder. The encoding process produces a bitstream (also referred to herein as a bit sequence), from the video, which can be stored or transmitted over a physical medium. A decoder performs a decoding process to read the bitstream and, thereby, derive the sequence of pictures of the video. As used herein, the term “coding” is used to refer to processes and algorithms used during either the encoding process or the decoding process or both, and the term coding is used interchangeably herein with the term encoding and the term decoding.
The video coding process comprises a plurality of algorithms some of which are properly arranged to achieve video compression by reducing redundant or non-important information within and between the video frames. One of these algorithms is quantization, which involves compressing ranges of transform coefficient values into individual quantum values to generate quantized transform coefficients that are used, by the encoder, to generate the bitstream of the video. The decoder dequantizes the quantized transform coefficients to recreate the video. Currently, quantization and dequantization algorithms are optimized for square blocks of coefficients e.g., transform coefficients and quantized transform coefficients, respectively.
However, there is a need for methods and apparatus for quantization and dequantization of rectangular blocks of coefficients.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
USPTO Backgrounds
USPTO Backgrounds