Field/frame adaptive coding and decoding method with field/frame index and apparatus for performing the same
View Patent ↗A moving picture coding method for coding a picture when switching between frame coding and field coding adaptively on a block-by-block basis. The method including determining the maximum number of reference indices for field coding for specifying fields which are to be referred to at the time of field coding, using the maximum number of reference indices for frame coding for specifying frames which are to be referred to at the time of frame coding, and assigning to fields the reference indices for field coding for specifying fields which are to be referred to at the time of field coding, within a range of the determined maximum number thereof, using the reference indices for frame coding for specifying frames which are to be referred to at the time of frame coding.
1. A coding method for coding blocks of picture data, said coding method comprising:
generating, by a command generation unit, a sequence of commands for respectively assigning frame-indices, used for frame coding, to reference frames of the blocks of picture data;
adaptively switching, by a processor and on a block-by-block basis of the blocks of picture data, between frame coding and field coding;
specifying, by a reference frame specification unit and in a case where frame coding is performed on a block of picture data of the blocks of picture data, a reference frame, which is referred to when coding the block of picture data, according to a frame-index included in the assigned frame-indices assigned by the sequence of commands;
specifying, by a reference field specification unit and in a case where field coding is performed on the block of picture data, a reference field, which is referred to when coding the block of picture data, according to a field-index, which is for field coding the block of picture data and which is generated using the frame-index included in the assigned frame-indices;
coding, by a reference index coding unit and as a reference index, the frame-index, which is used for specifying the reference frame, in the case where frame coding is performed on the block of picture data;
coding, by the reference index coding unit and as a reference index, the field-index, which is used for specifying the reference field, in the case where field coding is performed on the block of picture data;
coding information indicating a maximum number of frame-indices; and
determining a maximum number of field-indices to be double a value of the maximum number of frame-indices,
wherein said specifying of the reference field includes:
determining the field-index so that a number of specified reference fields is not greater than the determined maximum number of field-indices;
specifying, as the field-index, a doubled value of a value of the frame-index, which is used for specifying a reference frame including the reference field, in a case where the reference field has a same parity as a parity of a field including the block of picture data; and
specifying, as the field-index, a value obtained by adding one to the doubled value of the value of the frame-index, which is used for specifying the reference frame including the reference field, in a case where the reference field has a different parity from the parity of the field including the block of picture data.
2. A non-transitory computer-readable recording medium having a program stored thereon, the program for coding an image signal, and the program causing a computer to execute a coding method comprising:
generating, by a command generation unit, a sequence of commands for respectively assigning frame-indices, used for frame coding, to reference frames of the blocks of picture data;
adaptively switching, by a processor and on a block-by-block basis of the blocks of picture data, between frame coding and field coding;
specifying, by a reference frame specification unit and in a case where frame coding is performed on a block of picture data of the blocks of picture data, a reference frame, which is referred to when coding the block of picture data, according to a frame-index included in the assigned frame-indices assigned by the sequence of commands;
specifying, by a reference field specification unit and in a case where field coding is performed on the block of picture data, a reference field, which is referred to when coding the block of picture data, according to a field-index, which is for field coding the block of picture data and which is generated using the frame-index included in the assigned frame-indices;
coding, by a reference index coding unit and as a reference index, the frame-index, which is used for specifying the reference frame, in the case where frame coding is performed on the block of picture data;
coding, by the reference index coding unit and as a reference index, the field-index, which is used for specifying the reference field, in the case where field coding is performed on the block of picture data;
coding information indicating a maximum number of frame-indices; and
determining a maximum number of field-indices to be double a value of the maximum number of frame-indices,
wherein said specifying of the reference field includes:
determining the field-index so that a number of specified reference fields is not greater than the determined maximum number of field-indices;
specifying, as the field-index, a doubled value of a value of the frame-index, which is used for specifying a reference frame including the reference field, in a case where the reference field has a same parity as a parity of a field including the block of picture data; and
specifying, as the field-index, a value obtained by adding one to the doubled value of the value of the frame-index, which is used for specifying the reference frame including the reference field, in a case where the reference field has a different parity from the parity of the field including the block of picture data.
3. A coding apparatus for coding blocks of picture data while adaptively switching, on a block-by-block basis of the blocks of picture data, between frame coding and field coding, said coding apparatus comprising:
a command generation unit operable to generate a sequence of commands for respectively assigning frame-indices, used for frame coding, to reference frames of the blocks of picture data;
a coding unit operable to code information indicating a maximum number of frame-indices;
a reference frame/field specification unit operable to:
specify, in a case where frame coding is performed on a block of picture data of the blocks of picture data, a reference frame, which is referred to when coding the block of picture data, according to a frame-index included in the assigned frame-indices assigned by the sequence of commands; and
specify, in a case where field coding is performed on the block of picture data, a reference field, which is referred to when coding the block of picture data, according to a field-index, which is for field coding the block of picture data and which is generated using the frame-index included in the assigned frame-indices; and
a reference index coding unit operable to:
code, as a reference index, the frame-index, which is used for specifying the reference frame, in the case where frame coding is performed on the block of picture data; and
code, as a reference index, the field-index, which is used for specifying the reference field, in the case where field coding is performed on the block of picture data,
wherein said reference frame/field specification unit:
specifies the reference field by determining the field-index so that a number of specified reference fields is not greater than a determined maximum number of field-indices that is double a value of the maximum number of frame-indices;
specifies, as the field-index, a doubled value of a value of the frame-index, which is used for specifying a reference frame including the reference field, in a case where the reference field has a same parity as a parity of a field including the block of picture data; and
specifies, as the field-index, a value obtained by adding one to the doubled value of the value of the frame-index, which is used for specifying the reference frame including the reference field, in a case where the reference field has a different parity from the parity of the field including the block of picture data.