Moving image coding method, moving image coding apparatus, program, and integrated circuit

A moving image coding apparatus that codes an input image to generate a coded bit stream, and transmits the coded bit stream through a transmission channel, said moving image coding apparatus comprising:

• an image converting unit configured to change at least one of a resolution and a frame rate of the input image, according to a degree of difficulty in coding the input image, and to output an image to be coded;
• a moving image coding unit configured to code the image outputted by said image converting unit to generate the coded bit stream, and to transmit the coded bit stream through the transmission channel;
• a bit rate determining unit configured to determine a coding bit rate that is a bit rate of the coded bit stream transmitted through the transmission channel;
• and
• a resolution range selecting unit configured to select a resolution range for determining an upper limit of a resolution of the image to be coded according to the coding bit rate determined by said bit rate determining unit,
• wherein, when the resolution of the image to be coded is to be increased, said image converting unit is configured to determine a new resolution so that the resolution of the image to be coded does not exceed the upper limit determined by said resolution range selecting unit,
• wherein said resolution range selecting unit determines a lower limit of the resolution of the image to be coded according to the coding bit rate determined by said bit rate determining unit, such that the upper limit of the resolution of the image to be coded is a different value than the lower limit of the resolution of the image to be coded, and
• wherein, when the resolution of the image to be coded is to be decreased, the new resolution is determined by said image converting unit so that the resolution of the image to be coded does not fall below the lower limit determined by said resolution range selecting unit.

A non-transitory computer-readable recording medium for use in a computer, said non-transitory computer-readable recording medium having a program causing a computer to code an input image to generate a coded bit stream, and transmit the coded bit stream through a transmission channel, the program causing the computer to execute a method comprising:

• changing at least one of a resolution and a frame rate of the input image, according to a degree of difficulty in coding the input image, and outputting an image to be coded;
• coding the image outputted in said changing to generate the coded bit stream, and transmitting the coded bit stream through the transmission channel;
• determining a coding bit rate that is a bit rate of the coded bit stream transmitted through the transmission channel;
• and
• selecting a resolution range for determining an upper limit of a resolution of the image to be coded according to the coding bit rate determined in said determining,
• wherein, when the resolution of the image to be coded is to be increased, a new resolution is determined in said changing so that the resolution of the image to be coded does not exceed the upper limit determined in said selecting,
• wherein, in said selecting, a lower limit of the resolution of the image to be coded is determined according to the coding bit rate determined in said determining, such that the upper limit of the resolution of the image to be coded is a different value than the lower limit of the resolution of the image to be coded, and
• wherein, when the resolution of the image to be coded is to be decreased, the new resolution is determined in said changing so that the resolution of the image to be coded does not fall below the lower limit determined in said selecting.

An integrated circuit that codes an input image to generate a coded bit stream, and transmits the coded bit stream through a transmission channel, said integrated circuit comprising:

• an image converting unit configured to change at least one of a resolution and a frame rate of the input image, according to a degree of difficulty in coding the input image, and to output an image to be coded;
• a moving image coding unit configured to code the image outputted by said image converting unit to generate the coded bit stream, and to transmit the coded bit stream through the transmission channel;
• a bit rate determining unit configured to determine a coding bit rate that is a bit rate of the coded bit stream transmitted through the transmission channel;
• and
• a resolution range selecting unit configured to select a resolution range for determining an upper limit of a resolution of the image to be coded according to the coding bit rate determined by said bit rate determining unit,
• wherein, when the resolution of the image to be coded is to be increased, said image converting unit is configured to determine a new resolution so that the resolution of the image to be coded does not exceed the upper limit determined by said resolution range selecting unit,
• wherein said resolution range selecting unit determines a lower limit of the resolution of the image to be coded according to the coding bit rate determined by said bit rate determining unit, such that the upper limit of the resolution of the image to be coded is a different value than the lower limit of the resolution of the image to be coded, and
• wherein, when the resolution of the image to be coded is to be decreased, the new resolution is determined by said image converting unit so that the resolution of the image to be coded does not fall below the lower limit determined by said resolution range selecting unit.