A real-time variable bit rate MPEG2 video coding method for digital storage media

A real-time coding that performs, in one coding pass, a variable bit rate coding that capitalizes on MPEG-2 video coding is proposed. In this method, coding is performed according to the degree of difficulty in image coding. To realize this objective, the relationship between quantization scale and generated bits is modeled as a bit amount assigning function. Based on this bit amount assigning function, the quantization scale is determined for each picture frame and coding is performed with this quantization scale. To verify this method, computer simulations are performed and MPEG-2 real-time encoders are built to realize the hardware installation of this method. From the results, it is confirmed that: 1. assignment of bit amounts in this method is executed in a similar fashion to that achieved in conventional two-pass variable bit rate coding, 2. Image quality can greatly be improved over the quality achieved in the constant bit rate coding, and 3. Coding performance remains stable even over extensive coding durations. Also, this method can be implemented using the same level of hardware as is required in constant bit rate coding. As a result, we have the prospect that two hours of high quality video can be recorded onto one side of a DVD-RAM disc in real time with the proposed method.