Method and device for controlling quantization scales of a video encoding bit stream

1. A method for controlling quantization scales when encoding video signals, comprising:

(a) generating a new quantization scale; and

(b) comparing the new quantization scale with a prior quantization scale by calculating and checking a difference between the new quantization scale and the prior quantization scale, and if the calculated difference between the new quantization scale and the prior quantization scale exceeds a predetermined range, replacing the prior quantization scale with the new quantization scale.

2. The method of claim 1 wherein the method further comprises performing steps (a) and (b) using a rate controller.

3. The method of claim 1 wherein the method further comprises performing steps (a) and (b) by executing a video encoding program.

4. A video quantizing device for quantizing video signals to generate a quantized matrix comprising:

a rate controller for providing quantization scales; and

a quantizer electrically connected to the rate controller for quantizing the video signals according to the quantization scales;

wherein the rate controller compares a new quantization scale with a prior quantization scale by calculating and checking a difference between the new quantization scale and the prior quantization scale, and if the calculated difference between the new quantization scale and the prior quantization scale exceeds a predetermined range, the rate controller provides the new quantization scale to the quantizer to replace the prior quantization scale.

5. A method for encoding digital video signals, the digital video signals including a plurality of macro blocks, the method comprising:

(a) encoding a current macro block using a first quantization scale; and

(b) calculating a difference between the first quantization scale and a second quantization scale, and determining whether to encode a next macro block using the second quantization scale instead of the first quantization scale according to the calculated difference between the first quantization scale and the second quantization scale.

6. An apparatus for encoding digital video signals, the digital video signals including a plurality of macro blocks, the apparatus comprising:

a rate controller for providing a quantization scale; and

a quantizer coupled for receiving the quantization scale to perform quantization to respective one of the macro blocks;

wherein the rate controller is further arranged to calculate a difference between a new value and a prior value of the quantization scale, and when the calculated difference indicates that the new value is significantly different from the prior value, the quantization scale provided by the rate controller is replaced with the new value.