US RE40,679 E1
	Picture encoding method, picture encoding apparatus and picture recording medium
Tsuyoshi Oda, Chiba (Japan)
Assigned to Sony Corporation, Tokyo (Japan)
Filed on Dec. 29, 1999, as Appl. No. 9/474,479.
Application 08/770593 is a continuation of application No. 08/351262, abandoned, previously published as PCT/JP94/00610, filed on Apr. 11, 1994.
Application 09/474479 is a reissue of application No. 08/770593, filed on Dec. 19, 1996, now 5,703,646, filed on Dec. 30, 1997.
Claims priority of application No. P5-105943 (JP), filed on Apr. 09, 1993.
Int. Cl. H04N 7/18 (2006.01)

U.S. Cl. 375—240.13  [375/240.04; 375/240.05; 375/240.06; 375/240.07; 375/240.03; 375/240.14; 375/240.18]

22 Claims

[ 16. An encoding method for encoding source video data, the method comprises the steps of: encoding said source video data with a predetermined quantization step size to generate first encoded data; detecting a difficulty of the encoding process of source video data based on bit amount of said first encoded data; deciding an optimum quantization step size, said optimum quantization step size being varied depending on said difficulty so that said optimum quantization step size becomes smaller when said source video data is more complex and said optimum quantization step size becomes larger when source video data to be encoded is more simple; and encoding said source video data by using said optimum quantization step on encoding unit basis, wherein the predetermined quantization step size has a fixed value and the optimum quantization step size has a non-fixed value, wherein said source video data is always encoded using said predetermined quantization step and said optimum quantization step in which the predetermined quantization step size is always different from the optimum quantization step size. ]