Method and system for a user to manually alter the quality of a previously encoded video sequence

摘要

A method and system in which a user manually changes the quality of specific time periods of encoded video. After the automatic encoding of video into a compressed digital format, a person editing the encoded video reviews the quality of the video and manually indicates that the quality of specific time periods of the video is to be altered. As the digital storage medium such as an optical disc which stores the encoded video has a finite storage capacity, the total number of bits for the encoded video and the quality of the video is limited. Consequently, in order to increase the quality for one time period, bits must be taken from other time periods. After the editor assigns the qualities to different time periods, a percentage of bits is removed from the time sequences and placed into a bit pool. The new number of bits for the various time periods are calculated using an exponential function and the bits in the bit pool are proportionally distributed to the video frames. The frames must then be checked and possibly adjusted to assure that underflow of the video buffer will not occur. After the underflow checking procedure, the video is re-encoded with an adjusted quantization in accordance with a quantizer model which will result in a picture having the calculated number of bits and a quality in accordance with the user's selection.