Fixed Buffer Real-Time Image Compression Technique

An apparatus for performing real-time compression on an image for a target buffer fullness, said image comprising 16×16 macro-blocks, said apparatus comprising:

• a buffer that stores said image;
• a discrete cosine transformation (DCT) unit that performs a DCT on each said 16×16 macro-blocks, wherein said DCT unit converts said image into a frequency map;
• a quantization unit that quantizes an output of said DCT, wherein a selected amount of information is discarded, wherein said compression divides each DCT output by a quantization coefficient and rounds-off the result to an integer, wherein said quantization unit comprises:
• a control unit that defines a quantization parameter scalar (Q) for each N macro-blocks of said image, wherein said control unit initializes Q to a value that correlates to a buffer fullness of a previously compressed image, wherein said control unit monitors said buffer fullness and compares said buffer fullness with a target buffer fullness, and wherein said control unit sets an appropriate Q value to be used in said quantization unit;
• a zig-zag scan unit that performs a zig-zag scan on the output being quantized;
• and
• an entropy coding unit that performs entropy coding on said quantization coefficient being zig-zag scanned.

A system for performing real-time compression on an image for a target buffer fullness, said system comprising:

• means for dividing said image into N macro-blocks, wherein said N macro-blocks comprises 16×16 macro-blocks;
• means for performing a discrete cosine transformation (DCT) on each said N macro-blocks;
• means for quantizing each of said N macro-blocks;
• means for defining a quantization matrix (Q*[M]) for each said N macro-blocks;
• means for initializing Q to a value that correlates to a buffer fullness of a previously compressed image;
• means for monitoring said buffer fullness by comparing said buffer fullness with a target buffer fullness;
• means for increasing the Q value to a first new value when said buffer fullness is greater than said target buffer fullness;
• means for decreasing said Q value to a second new value when said buffer fullness is greater than said target buffer fullness;
• means for performing a zig-zag scan for each of said N macro-blocks;
• and
• means for performing entropy encoding for each of said N macro-blocks.