The present invention allows higher quality video images to be transmitted
without a concomitant increase in a total number of video data bits
transmitted per frame. Quantization parameters are applied to
coefficients of macroblocks within a given video frame. A lower value of
the quantization parameter is applied near a central region of a video
frame. This central region is referred to as a prime video region.
Applying the lower quantization parameter to the prime video region has
the effect of increasing the video data bit density within that area.
Outside of the prime video region, the video data bit density per
macroblock is decreased so as to have a zero net-gain in bit density over
the entire video frame. Furthermore, there may be a plurality of prime
video regions where quantization parameters are dynamically coded. In
this case, the value of the quantization parameter will increase or
decrease within a given prime video region based on a relative importance
of a particular prime video region. Consequently, a quantization
parameter matrix may vary depending on the video scene.