Method and apparatus for controlling a target amount of code and for compressing video data

An apparatus for encoding source video data representative of a number of group of pictures (GOPS) each having a plurality of fields or frames, said apparatus comprising:

• means for processing the source video data so as to determine difficulty data of a field or frame which is indicative of the difficulty of the video data;
• computing means for determining a target code amount by using a ratio of the difficulty data of a respective field or frame to a sum of difficulty data of a predetermined plurality of said fields or frames, said computing means determining the target code amount such that the target code amount for an ith field or frame is determined by using the ratio of difficulty data of a (j)th field or frame to the sum of difficulty data of the predetermined plurality of fields or frames from the jth field or frame, the target code amount for an (i+1)th field or frame is determined by using the ratio of difficulty data of a (j+1)th field or frame to the sum of difficulty data of the predetermined plurality of fields or frames from the (j+1)th field or frame, the target code amount for an (i+2)th field or frame is determined by using the ratio of difficulty data of a (j+2)th field or frame to the sum of difficulty data of the predetermined plurality of fields or frames from the (j+2)th field or frame, and so forth;
• and
• means for encoding at least a portion of the video data in accordance with said target code amount.

A method for encoding source video data representative of a plurality of images, said method comprising the steps of:

• determining a target code amount by using a ratio of difficulty data of a respective picture to a sum of difficulty data of a predetermined plurality of pictures within said source video data;
• and
• encoding at least a portion of the source video data in accordance with said target code amount,
• said determining step determines the target code amount such that the target code amount for an (i)th picture is determined by using the ratio of difficulty data of a (j)th picture to the sum of difficulty data of the predetermined plurality of pictures from the (j)th picture, the target code amount for an (i+1)th picture is determined by using the ratio of difficulty data of a (j+1)th picture to the sum of difficulty data of the predetermined plurality of pictures from the (j+1)th picture, the target code amount for an (i+2)th picture is determined by using the ratio of difficulty data of a (j+2)th picture to the sum of difficulty data of the predetermined plurality of pictures from the (j+2)th picture, and so forth.

A method for encoding source video data representative of a number of group of pictures (GOPs) each having a plurality of fields or frames, said method comprising the steps of:

• processing the source video data so as to determine difficulty data of a field or frame which is indicative of the difficulty of the video data;
• determining a target code amount by using a ratio of the difficulty data of a respective field or frame to a sum of difficulty data of a predetermined plurality of said fields or frames such that the target code amount for an ith field or frame is determined by using the ratio of difficulty data of a (j)th field or frame to the sum of difficulty data of the predetermined plurality of fields or frames from the jth field or frame, the target code amount for an (i+1)th field or frame is determined by using the ratio of difficulty data of a (j+1)th field or frame to the sum of difficulty data of the predetermined plurality of fields or frames from the (j+1)th field or frame, the target code amount for an (i+2)th field or frame is determined by using the ratio of difficulty data of a (j+2)th field or frame to the sum of difficulty data of the predetermined plurality of fields or frames from the (j+2)th field or frame image, and so forth;
• and
• encoding at least a portion of the video data in accordance with said target code amount.