Decoding apparatus, encoding apparatus, decoding method, encoding method, and program

An encoding apparatus comprising:

• an image division unit configured to (i) obtain an input image and (ii) divide the input image into a first image and a second image;
• a first encoder configured to (i) receive the first image and (ii) generate a first plurality of slices of the first image;
• a second encoder configured to (i) receive the second image and (ii) generate a second plurality of slices of the second image;
• a control unit configured to control an image encoding unit and an arithmetic encoding unit in the first encoder and the second encoder so as to satisfy at least a first condition and a second condition,
• wherein the first condition comprises a difference between a total number of encoding block lines included in any N consecutive slices and a total number of encoding block lines included in N consecutive slices different from the any N consecutive slices is 1 or less,
• wherein the second condition comprises a code amount of each slice is less than a predetermined upper limit code amount;
• and
• a stream coupling unit configured to (i) generate a stream by combining the first plurality of slices and the second plurality of slices, (ii) to add a delay reduction flag indicating that at least the first condition and the second condition are satisfied in the generated stream, and (iii) output the generated stream to an encoder, wherein a decoding start time is determined using (i) a frame rate of the image stream, (ii) a number of encoding block lines per image in the image stream, and (iii) a decoding time of each image in the image stream.

A decoding method for performing decoding processing in parallel, the method comprising:

• obtaining, from an encoder, an image stream that comprises a plurality of slices, each slice being composed of at least one encoding block line;
• determining a presence or an absence of a delay reduction flag in the obtained image stream;
• based on determining the presence of the delay reduction flag, determining a decoding start time of each slice of the plurality of slices, the decoding start time determined using (i) a frame rate of the image stream, (ii) a number of encoding block lines per image in the image stream, and (iii) a decoding time of each image in the image stream;
• in response to determining the decoding start time for a respective slice has been reached, performing, using a plurality of arithmetic decoding units and a plurality of image decoding units, arithmetic decoding processing on the respective slice in a predetermined order of each arithmetic decoding unit, wherein the arithmetic decoding process initiates decoding of a respective slice at time intervals corresponding to slice sizes on the image stream that satisfy conditions of:
• a difference between (i) a total number of encoding block lines included in N consecutive slices and (ii) a total number of encoding block lines included in another set of N consecutive slices is 1 or less, and
• (ii) an amount of code that is controlled for processing the respective slice is within a predetermined upper limit code amount.