Method of decoding motion vector

An apparatus of decoding an image in an advanced motion vector prediction (AMVP) mode, the apparatus comprising:

• an entropy decoder to obtain an inter prediction information and quantized coefficient components from a received bitstream;
• an inverse scanner to apply an inverse scan pattern on the quantized coefficient components to generate a quantized block;
• an inverse quantizer to inversely quantize the quantized block using a quantization parameter and a quantization matrix;
• an inverse transformer to inversely transform the inversely quantized block to generate a residual block;
• an inter predictor to restore motion information from the inter prediction information and generate a prediction block of a current block using the motion information,
• wherein the motion information is restored by performing the sub-steps of:
• constructing an AMVP list using available motion vector candidates of a left motion vector candidate, an above motion vector candidate and a temporal motion vector candidate;
• determining a motion vector predictor among motion vector candidates of the AMVP candidate list;
• restoring a motion vector by using the inter prediction information;
• and
• wherein the quantization parameter is determined per a quantization unit and is restored by using a differential quantization parameter and a quantization parameter predictor,
• wherein the quantization parameter predictor is generated by averaging two quantization parameters of a left quantization parameter, an above quantization parameter and a previous quantization parameter if two or more of the left quantization parameter, the above quantization parameter and the previous quantization parameter are available,
• wherein an average of the above and previous quantization parameters is set as the quantization parameter predictor when the left quantization parameter is unavailable,
• wherein the temporal motion vector candidate is a motion vector of a temporal motion vector candidate block within a temporal motion vector candidate picture, and the temporal motion vector candidate is determined depending on a position of the temporal motion vector candidate block within a largest coding unit (LCU), and
• wherein if the current block is adjacent to a lower LCU, a right-below corner block is set as unavailable.

A non-transitory computer-readable storage medium storing encoded video information and including computer executable instructions, wherein the encoded video information is generated by the instructions performing the steps of:

• determining motion information of a current block, and generating a prediction block of the current block using the motion information;
• transforming a residual block generated using the prediction block to generate a transformed block;
• quantizing the transformed block using a quantization parameter and a quantization matrix to generate a quantized block;
• scanning quantized coefficient components of the quantized block;
• and
• performing entropy-coding on the scanned quantized coefficient components of the quantized block,
• wherein the motion information is encoded by performing the sub-steps of:
• constructing an AMVP list using available motion vector candidates of a left motion vector candidate, an above motion vector candidate and a temporal motion vector candidate;
• selecting a motion vector predictor among motion vector candidates of the AMVP candidate list;
• generating a differential motion vector by subtracting the motion vector predictor from a motion vector of the current block;
• and
• encoding a reference picture index, the differential motion vector and an AMVP index specifying the motion vector predictor,
• wherein the quantization parameter is determined per a quantization unit, a differential quantization parameter generated using a quantization parameter predictor is converted into bins for indicating the absolute value and a bin for indicting a sign, and the bins for indicating the absolute value and the bin for indicting a sign are encoded,
• wherein the quantization parameter predictor is generated by averaging two quantization parameters of a left quantization parameter, an above quantization parameter and a previous quantization parameter if two or more of the left quantization parameter, the above quantization parameter and the previous quantization parameter are available,
• wherein an average of the above and previous quantization parameters is set as the quantization parameter predictor when the left quantization parameter is unavailable,
• wherein the temporal motion vector candidate is a motion vector of a temporal motion vector candidate block within a temporal motion vector candidate picture, and the temporal motion vector candidate is determined depending on a position of the temporal motion vector candidate block within a largest coding unit (LCU), and
• wherein if the current block is adjacent to a lower LCU, a right-below corner block is set as unavailable.