Moving image encoding apparatus, method of controlling the same, and program

A moving image encoding apparatus for performing prediction encoding using inter prediction and intra prediction, comprising:

• a storage unit configured to store an encoding target image;
• a reference image storage unit configured to store a reference image for the prediction encoding;
• a prediction mode decision unit configured to decide one of an inter prediction mode and an intra prediction mode as a prediction mode for a prediction target block in the encoding target image based on the encoding target image and the reference image;
• and
• an encoding unit configured to perform the prediction encoding of the encoding target image in accordance with the decided prediction mode,
• wherein said prediction mode decision unit comprising:
• a search range setting unit configured to set a search range in the reference image;
• a pattern matching unit configured to perform pattern matching using the encoding target image and the reference image read out based on the search range and searching for a region where a cost is minimum, said pattern matching unit calculating the cost as a cost of a first intra prediction mode using a first cost function according to a picture type that is I picture or calculating the cost as a cost of an inter prediction mode using a second cost function according to the picture type that is one of B picture and P picture;
• an intra prediction unit configured to calculate the cost based on the first cost function for each of a plurality of predetermined intra prediction modes using the encoding target image and the reference image and deciding a second intra prediction mode for which the calculated cost is minimum;
• an intra prediction mode decision unit configured to, when said pattern matching unit has calculated the cost of the first intra prediction mode, compare the cost with the cost of the second intra prediction mode decided by said intra prediction unit and deciding an intra prediction mode having a lower cost;
• and
• a determination unit configured to, when said pattern matching unit has calculated the cost of the inter prediction mode, compare the cost with the cost of the second intra prediction mode decided by said intra prediction unit and determining a prediction mode having a lower cost,
• wherein said encoding unit performs the prediction encoding in accordance with one of the intra prediction mode decided by said intra prediction mode decision unit and the prediction mode decided by said determination unit.

A method of controlling a moving image encoding apparatus for performing prediction encoding using inter prediction and intra prediction, the moving image encoding apparatus including:

• a storage unit configured to store an encoding target image;
• a reference image storage unit configured to store a reference image for the prediction encoding;
• a prediction mode decision unit configured to decide one of an inter prediction mode and an intra prediction mode as a prediction mode for a prediction target block in the encoding target image based on the encoding target image and the reference image;
• and
• an encoding unit configured to perform the prediction encoding of the encoding target image in accordance with the decided prediction mode,
• the method comprising steps of, by said prediction mode decision unit:
• setting a search range in the reference image;
• performing pattern matching using the encoding target image and the reference image read out based on the search range and searching for a region where a cost is minimum, and calculating the cost as a cost of a first intra prediction mode using a first cost function according to a picture type that is I picture or calculating the cost as a cost of an inter prediction mode using a second cost function according to the picture type that is one of B picture and P picture;
• calculating the cost based on the first cost function for each of a plurality of predetermined intra prediction modes using the encoding target image and the reference image and deciding a second intra prediction mode for which the calculated cost is minimum;
• when the cost of the first intra prediction mode has been calculated in the pattern matching, comparing the cost with the cost of the decided second intra prediction mode and deciding an intra prediction mode having a lower cost;
• and
• when the cost of the inter prediction mode has been calculated in the pattern matching, comparing the cost with the cost of the decided second intra prediction mode and determining a prediction mode having a lower cost,
• wherein the prediction encoding is performed by said encoding unit in accordance with one of the decided intra prediction mode and the determined prediction mode.

A non-transitory computer readable storage medium storing a program for controlling a moving image encoding apparatus for performing prediction encoding using inter prediction and intra prediction, the moving image encoding apparatus including:

• a storage unit configured to store an encoding target image;
• a reference image storage unit configured to store a reference image for the prediction encoding;
• a prediction mode decision unit configured to decide one of an inter prediction mode and an intra prediction mode as a prediction mode for a prediction target block in the encoding target image based on the encoding target image and the reference image;
• and
• an encoding unit configured to perform the prediction encoding of the encoding target image in accordance with the decided prediction mode,
• the program causing said prediction mode decision unit to perform steps of:
• setting a search range in the reference image;
• performing pattern matching using the encoding target image and the reference image read out based on the search range and searching for a region where a cost is minimum, and calculating the cost as a cost of a first intra prediction mode using a first cost function according to a picture type that is I picture or calculating the cost as a cost of an inter prediction mode using a second cost function according to the picture type that is one of B picture and P picture;
• calculating the cost based on the first cost function for each of a plurality of predetermined intra prediction modes using the encoding target image and the reference image and deciding a second intra prediction mode for which the calculated cost is minimum;
• when the cost of the first intra prediction mode has been calculated in the pattern matching, comparing the cost with the cost of the decided second intra prediction mode and deciding an intra prediction mode having a lower cost;
• and
• when the cost of the inter prediction mode has been calculated in the pattern matching, comparing the cost with the cost of the decided second intra prediction mode and determining a prediction mode having a lower cost,
• wherein the prediction encoding is performed by said encoding unit in accordance with one of the decided intra prediction mode and the determined prediction mode.