Method of video coding for handheld apparatus

1. A method of coding blocks of video data in a video coder of a handheld apparatus comprising a battery and the video coder, said method comprising the steps of:

computing a residual error block from the use of a set of prediction functions having different power consumption levels,

enabling or disabling a prediction function of the set depending on its associated power consumption level for a predetermined level of the battery,

selecting a prediction function among a set of enabled prediction functions to code the residual error block.

2. A video coding method as claimed in claim 1 , wherein the selection step is based on a cost value depending on an entropy of a current block of residual data after run-length coding, on a reconstruction error between the corresponding decoded block and reference block, and on a quantization value of the current block.

3. A video coding method as claimed in claim 1 , wherein a prediction function is computed from a difference of a current pixel (x(i,j)) of a current block (X) and at least a value of a vertical segment (A) of pixels adjacent to the left of the current block and/or a horizontal segment (B) of pixels adjacent to the top of the current block.

4. A method of video coding as claimed in claim 1 , wherein a prediction function is computed from a difference of a current pixel (x(i,j)) of a current block (X) in a current frame (F(t)) and a corresponding pixel (y(i,j)) of a corresponding block (Y) in an immediately past frame (F(t- 1 )).

5. A method of video coding as claimed in claim 1 , wherein a prediction function is computed from a difference of a current pixel (x(i,j)) of a current block (X) in a current frame (F(t)) and a maximum (h 1 ,h 2 ) of a histogram of a corresponding block (Y) in an immediately past frame (F(t- 1 )), said maximum being the closest to the value of the current pixel.

6. A video coder for a handheld apparatus comprising a battery for supplying said video coder, the video coder being able to code blocks of video data and comprising a processor configured to:

compute a residual error block using a set of prediction functions having different power consumption levels,

enable or disable a prediction function of the set depending on the prediction function's associated power consumption level for a predetermined level of the battery, and

select a prediction function among a set of enabled prediction functions to code the residual error block.

7. A handheld apparatus comprising;

a battery; and

a video coder that uses power supplied by the battery and is configured to

compute a residual error block using a set of prediction functions having different power consumption levels,

enable or disable a prediction function of the set depending on the prediction function's associated power consumption level for a predetermined level of the battery, and

select a prediction function among a set of enabled prediction functions to code the residual error block.

8. A computer readable storage medium having processor-executable program instructions stored thereon, for coding blocks of video data for a handheld device including a battery, wherein execution of said program instructions by a processor causes the processor to perform video coding operations including

computing a residual error block using a set of prediction functions having different power consumption levels,

enabling or disabling a prediction function of the set based upon the prediction function's associated power consumption level for a predetermined level of the battery, and

selecting an enabled prediction function from the set of prediction functions to code the residual error block.

9. The video coder of claim 6 , wherein the processor is configured to select a prediction function based on a cost value depending on an entropy of a current block of residual data after run-length coding, on a reconstruction error between the corresponding decoded block and reference block, and on a quantization value of the current block.

10. The video coder of claim 6 , wherein the processor is configured to compute a prediction function from a difference of a current pixel (x(i,j)) of a current block (X) and at least a value of a vertical segment (A) of pixels adjacent to the left of the current block and/or a horizontal segment (B) of pixels adjacent to the top of the current block.

11. The video coder of claim 6 , wherein the processor is configured to compute a prediction function from a difference of a current pixel (x(i,j)) of a current block (X) in a current frame (F(t)) and a corresponding pixel (y(i,j)) of a corresponding block (Y) in an immediately past frame (F(t- 1 )).

12. The video coder of claim 6 , wherein the processor is configured to compute a prediction function from a difference of a current pixel (x(i,j)) of a current block (X) in a current frame (F(t)) and a maximum (h 1 ,h 2 ) of a histogram of a corresponding block (Y) in an immediately past frame (F(t- 1 )), said maximum being the closest to the value of the current pixel.

13. The video coder of claim 6 , wherein the video coder includes a video codec that encodes and decodes video data, and wherein the processor is configured to enable or disable a prediction function of the set by enabling or disabling a prediction function based upon the power consumption level of the video codec when the video codec uses the prediction function.

14. The method of claim 1 , wherein enabling or disabling a prediction function of the set includes enabling or disabling a prediction function based upon the power consumption level of a video codec when the video codec uses the prediction function.