公开(公告)号：EP1862012A1

公开(公告)日：2007-12-05

申请号：EP06748632.4

申请日：2006-03-22

申请人： QUALCOMM INCORPORATED

发明人： LIU, Shizhong ,  DO, Phan, L. ,  HUANG, William, Yee-Ming ,  HAN, Charles, S. ,  JALIL, Suhail

IPC分类号： H04N7/30 ,  G06T9/00 ,  H04N7/26

CPC分类号： H04N19/192 ,  H04N19/115 ,  H04N19/124 ,  H04N19/132 ,  H04N19/136 ,  H04N19/147 ,  H04N19/149 ,  H04N19/15 ,  H04N19/172 ,  H04N19/18 ,  H04N19/60

摘要： A dynamically scaled file encoding method and apparatus are disclosed. A file encoding system using JPEG encoding can be configured to produce relatively constant compressed file sizes irrespective of the initial file size and file contents. The system retrieves an initial file or image that is to be compressed and determines a target bit rate corresponding to the compressed file. The target bit rate is used to determine an initial scaling factor. The initial file is encoded using a JPEG encoder having coefficients scaled by the initial scaling factor. The resultant bit rate can be adjusted in a second loop if greater than the desired bit rate. To adjust the bit rate, a recomputed scaling factor is determined from the resultant bit rate. The initial file is then encoded with coefficients scaled by the recomputed scaling factor to achieve a bit rate that is within the target bit rate.