Method for setting motion vector list and apparatus using same

A picture decoding method by a decoding apparatus, the method comprising:

• checking a first motion vector predictor (MVP) candidate, wherein the first MVP candidate is checked from first neighboring blocks including a lower left block and a left block of a current block;
• setting a value of scaling information based on whether scaling for a motion vector of an available block from the first neighboring blocks has been performed for the first MVP candidate;
• checking a second MVP candidate, wherein the second MVP candidate is checked from second neighboring blocks including an upper right block, an upper block, and an upper left block of the current block, and wherein a motion vector of a specific block which is available or a scaled motion vector of the motion vector of the specific block from the second neighboring blocks is used for the second MVP candidate;
• constructing a list of MVP candidates based on at least one of the first MVP candidate or the second MVP candidate;
• deriving a motion vector for the current block based on an MVP for the current block, wherein the MVP for the current block is selected from the list of MVP candidates;
• generating a prediction sample of the current block based on the derived motion vector;
• and
• storing information on the reference picture for the specific block and information on the reference picture of the current block,
• wherein the scaling information indicates whether the scaled motion vector for the second MVP candidate is available, wherein an initial value of the scaling information is equal to 0;
• wherein the value of the scaling information is set equal to 1 when scaling for a motion vector of an available block from the first neighboring blocks has been performed for the first MVP candidate,
• wherein, when the value of the scaling information is equal to 0 and a reference picture of the specific block is different from a reference picture of the current block, the scaled motion vector is used for the second MVP candidate, and
• wherein, when the value of the scaling information is equal to 1, the scaled motion vector is not available for the second MVP candidate.

A picture encoding method by an encoding apparatus, the method comprising:

• checking a first motion vector predictor (MVP) candidate, wherein the first MVP candidate is checked from first neighboring blocks including a lower left block and a left block of a current block;
• setting a value of scaling information based on whether scaling for a motion vector of an available block from the first neighboring blocks has been performed for the first MVP candidate;
• checking a second MVP candidate, wherein the second MVP candidate is checked from second neighboring blocks including an upper right block, an upper block, and an upper left block of the current block, and wherein a motion vector of a specific block which is available or a scaled motion vector of the motion vector of the specific block from the second neighboring blocks is used for the second MVP candidate;
• constructing a list of MVP candidates based on at least one of the first MVP candidate or the second MVP candidate;
• determining an MVP for the current block, wherein the MVP for the current block is selected from the list of MVP candidates;
• deriving a motion vector for the current block based on an MVP for the current block;
• generating a prediction sample of the current block based on the derived motion vector;
• and
• encoding picture information including MVP information indicating one of the MVP candidates as the MVP for the current block and a residual information derived from the prediction sample,
• wherein the scaling information indicates whether the scaled motion vector for the second MVP candidate is available, wherein an initial value of the scaling information is equal to 0,
• wherein the value of the scaling information is set equal to 1 when scaling for a motion vector of an available block from the first neighboring blocks has been performed for the first MVP candidate,
• wherein, when the value of the scaling information is equal to 0 and a reference picture of the specific block is different from a reference picture of the current block, the scaled motion vector is used for the second MVP candidate, and
• wherein, when the value of the scaling information is equal to 1, the scaled motion vector is not available for the second MV candidate.

A non-transitory decoder-readable storage medium storing encoded picture information generated by performing the steps of:

• checking a first motion vector predictor (MVP) candidate, wherein the first MVP candidate is checked from first neighboring blocks including a lower left block and a left block of a current block;
• setting a value of scaling information based on whether scaling for a motion vector of an available block from the first neighboring blocks has been performed for the first MVP candidate;
• checking a second MVP candidate, wherein the second MVP candidate is checked from second neighboring blocks including an upper right block, an upper block, and an upper left block of the current block, and wherein a motion vector of a specific block which is available or a scaled motion vector of the motion vector of the specific block from the second neighboring blocks is used for the second MVP candidate;
• constructing a list of MVP candidates based on at least one of the first MVP candidate or the second MVP candidate;
• determining an MVP for the current block, wherein the MVP for the current block is selected from the list of MVP candidates;
• and
• deriving a motion vector for the current block based on an MVP for the current block;
• generating a prediction sample of the current block based on the derived motion vector and;
• encoding picture information including MVP information indicating one of the MVP candidates as the MVP for the current block and a residual information derived from the prediction sample,
• wherein the scaling information indicates whether the scaled motion vector for the second MVP candidate is available, wherein an initial value of the scaling information is equal to 0,
• wherein the value of the scaling information is set equal to 1 when scaling for a motion vector of an available block from the first neighboring blocks has been performed for the first MVP candidate,
• wherein, when the value of the scaling information is equal to 0 and a reference picture of the specific block is different from a reference picture of the current block, the scaled motion vector is used for the second MVP candidate, and
• wherein, when the value of the scaling information is equal to 1, the scaled motion vector is not available for the second MV candidate.