Encoder, data file, encoding method, computer readable medium and computer data signal

Abstract

An encoder includes a prediction unit and a code generation unit. The prediction unit predicts target data and judges whether prediction is right or wrong. When the prediction unit judges that consecutive predictions for respective target data are wrong, the code generation unit generates coded data including symbols corresponding to the respective target data for which the consecutive wrong predictions are made, using a code representing number of the consecutive predictions judged as wrong.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be described in detail based on the following figures, wherein:

FIG. 1 is a diagram showing the functional configuration of an encoding program 9 for performing an encoding process by a predictive encoding method;

FIGS. 2A to 2C are views for explaining the encoding process based on the encoding program 9;

FIG. 3 is a diagram showing the hardware configuration of the encoder 2 using an encoding method according to an exemplary embodiment of the invention;

FIG. 4 is a diagram showing the functional configuration of an encoding program 5 executed by the controller 20 (FIG. 3) for implementing the encoding method according to the exemplary embodiment of the invention;

FIG. 5 is a view showing a code table 582 provided by a code-table providing section 580;

FIG. 6 is a flow chart of an encoding process (S10) based on the encoding program 5 (FIG. 4);

FIGS. 7A to 7C are views for explaining coding efficiency of the encoding program 5; and

FIGS. 8A to 8C are views showing coded data (data file) in the case where another exemplary embodiment of the invention is applied to a run-length coding method.

Claims

1. An encoder comprising: a prediction unit that predicts target data and judges whether prediction is right or wrong; anda code generation unit that, wherein when the prediction unit judges that consecutive predictions for respective target data are wrong, the code generation unit generates coded data including symbols corresponding to the respective target data for which the consecutive wrong predictions are made, using a code representing number of the consecutive predictions judged as wrong.

2. The encoder according to claim 1, further comprising: a code assignment unit that outputs to the code generation unit a table in which different codes are assigned to respective numbers of consecutive predictions judged as wrong, which are equal to or less than an upper limit value, wherein:the code generation unit generates the code data including (i) the symbols corresponding to the respective target data for which the consecutive wrong predictions are made and (ii) a code assigned to the number of the consecutive wrong predictions for the respective target data, in accordance with the table output from the code assignment unit.

3. The encoder according to claim 2, wherein the upper limit value is equal to or larger than 2.

4. The encoder according to claim 2, wherein the code assignment unit stores the table, which is prepared in advance.

5. The encoder according to claim 2, further comprising: an upper-limit decision unit that decides the upper limit value according to how frequently the prediction unit judges that prediction is wrong, wherein:the code assignment unit generates the table in which the different codes are assigned to numbers of consecutive predictions judged as wrong, which are equal to or less than the upper limit value.

6. The encoder according to claim 2, wherein the code assignment unit outputs the table in which difference codes in the same coding space to (i) information indicating that prediction made by the prediction unit is right and (ii) the respective numbers of consecutive predictions judged as wrong, which are equal to or less than the upper limit value.

7. The encoder according to claim 5, wherein the code assignment unit generates the table in which difference codes in the same coding space to (i) information indicating that prediction made by the prediction unit is right and (ii) the respective numbers of consecutive predictions judged as wrong, which are equal to or less than the upper limit value.

8. A data file encoded by a predictive coding method, the data file stored in a computer readable medium, comprising: right prediction data equivalent to such data that prediction is hit by a predetermined prediction method;wrong prediction data equivalent to such data that prediction is missed by the prediction method; andan entropy code indicating number of consecutive predictions judged as wrong, wherein:when wrong prediction data are continuous, the entropy code indicating the number of consecutive predictions judged as wrong is associated with the wrong prediction data.

9. An encoding method comprising: predicting target data;judging whether the predicting is right or wrong; andwhen it is judged that consecutive predictions for respective target data are wrong, generating coded data including symbols corresponding to the respective target data for which the consecutive wrong predictions are made with using a code representing number of the consecutive predictions judged as wrong.

10. A computer readable medium storing a program causing a computer to execute an encoding process comprising: predicting target data;judging whether the predicting is right or wrong; andwhen it is judged that consecutive predictions for respective target data are wrong, generating coded data including symbols corresponding to the respective target data for which the consecutive wrong predictions are made with using a code representing number of the consecutive predictions judged as wrong.

11. A computer data signal embodied in a carrier wave for enabling a computer to perform an encoding process comprising: predicting target data;judging whether the predicting is right or wrong; andwhen it is judged that consecutive predictions for respective target data are wrong, generating coded data including symbols corresponding to the respective target data for which the consecutive wrong predictions are made with using a code representing number of the consecutive predictions judged as wrong.

12. The encoder according to claim 1, wherein: the prediction unit comprises:a first prediction section that predicts a data value of the target data using a first prediction method; anda second prediction section that predicts the data value of the target data using a second prediction method different from the first prediction method.

13. The encoder according to claim 1, wherein the prediction unit predicts the target data using a run-length coding method.