Methods and apparatus relating to encoding and decoding stereoscopic (3D) image data, e.g., left and right eye images, are described. Various pre-encoding and post-decoding operations are described in conjunction with difference based encoding and decoding techniques. In some embodiments left and right eye image data is subject to scaling, transform operation(s) and cropping prior to encoding. In addition, in some embodiments decoded left and right eye image data is subject to scaling, transform operations(s) and filling operations prior to being output to a display device. Transform information and/or scaling information may be included in a bitstream communicating encoded left and right eye images. The amount of scaling can be the same for an entire scene and/or program.

Methods and apparatus relating to encoding and decoding stereoscopic (3D) image data, e.g., left and right eye images, are described. Various pre-encoding and post-decoding operations are described in conjunction with difference based encoding and decoding techniques. In some embodiments left and right eye image data is subject to scaling, transform operation(s) and cropping prior to encoding. In addition, in some embodiments decoded left and right eye image data is subject to scaling, transform operations(s) and filling operations prior to being output to a display device. Transform information and/or scaling information may be included in a bitstream communicating encoded left and right eye images. The amount of scaling can be the same for an entire scene and/or program.

The entropy coding of a current part of a predetermined entropy slice is based on, not only, the respective probability estimations of the predetermined entropy slice as adapted using the previously coded part of the predetermined entropy slice, but also probability estimations as used in the entropy coding of a spatially neighboring, in entropy slice order preceding entropy slice at a neighboring part thereof. Thereby, the probability estimations used in entropy coding are adapted to the actual symbol statistics more closely, thereby lowering the coding efficiency decrease normally caused by lower-delay concepts. Temporal interrelationships are exploited additionally or alternatively.

The entropy coding of a current part of a predetermined entropy slice is based on, not only, the respective probability estimations of the predetermined entropy slice as adapted using the previously coded part of the predetermined entropy slice, but also probability estimations as used in the entropy coding of a spatially neighboring, in entropy slice order preceding entropy slice at a neighboring part thereof. Thereby, the probability estimations used in entropy coding are adapted to the actual symbol statistics more closely, thereby lowering the coding efficiency decrease normally caused by lower-delay concepts. Temporal interrelationships are exploited additionally or alternatively.

A method of video processing is described. The method includes: making a first determination about whether a collocated video block of a video block of a video is coded using an inter coding mode or a non-inter coding mode; making a second determination, based on the first determination, about availability of motion vectors of the collocated video block or a mode of derivation of motion vectors for the collocated video block; and performing a conversion between the video block and a coded representation of the video based on the second determination.

A motion vector coding unit executes processing including a neighboring block specification step of specifying a neighboring block which is located in the neighborhood of a current block; a judgment step of judging whether or not the neighboring block has been coded using a motion vector of another block; a prediction step of deriving a predictive motion vector of the current block using a motion vector calculated from the motion vector of the other block as a motion vector of the neighboring block; and a coding step of coding the motion vector of the current block using the predictive motion vector.

A motion vector coding unit executes processing including a neighboring block specification step of specifying a neighboring block which is located in the neighborhood of a current block; a judgment step of judging whether or not the neighboring block has been coded using a motion vector of another block; a prediction step of deriving a predictive motion vector of the current block using a motion vector calculated from the motion vector of the other block as a motion vector of the neighboring block; and a coding step of coding the motion vector of the current block using the predictive motion vector.

A method of encoding an image in a merge mode, the method including determining motion information of a current prediction unit, and generating a prediction block using the motion information; generating a residual block using an original block and the prediction block, transforming the residual block to generating a transformed block, quantizing the transformed block using a quantization parameter to generate a quantized block, and scanning the quantized block to entropy-code the quantized block; and encoding the motion information using effective spatial and temporal merge candidates of the current prediction unit. Further, a motion vector of the temporal merge candidate is a motion vector of a temporal merge candidate within a temporal merge candidate picture, and the quantization parameter is encoded using an average of two effective quantization parameters among a left quantization parameter, an upper quantization parameter and a previous quantization parameter of a current coding unit, also when the quantized block is larger than a predetermined size, the quantized block is divided into a plurality of subblocks to be scanned, and a scan pattern for scanning the plurality of subblocks is the same as a scan pattern for scanning quantized coefficients within each subblock. In addition, information indicating a position of a last non-zero quantized coefficient in a transform unit is transmitted to a video decoder.

A method of encoding an image in a merge mode, the method including determining motion information of a current prediction unit, and generating a prediction block using the motion information; generating a residual block using an original block and the prediction block, transforming the residual block to generating a transformed block, quantizing the transformed block using a quantization parameter to generate a quantized block, and scanning the quantized block to entropy-code the quantized block; and encoding the motion information using effective spatial and temporal merge candidates of the current prediction unit. Further, a motion vector of the temporal merge candidate is a motion vector of a temporal merge candidate within a temporal merge candidate picture, and the quantization parameter is encoded using an average of two effective quantization parameters among a left quantization parameter, an upper quantization parameter and a previous quantization parameter of a current coding unit, also when the quantized block is larger than a predetermined size, the quantized block is divided into a plurality of subblocks to be scanned, and a scan pattern for scanning the plurality of subblocks is the same as a scan pattern for scanning quantized coefficients within each subblock. In addition, information indicating a position of a last non-zero quantized coefficient in a transform unit is transmitted to a video decoder.

Provided is an inter-layer video decoding method including obtaining a disparity vector of a current block included in a first layer image; determining a block of a second layer image corresponding to the current block by using the obtained disparity vector; determining a reference block including a sample that contacts a boundary of the block; obtaining a motion vector of the reference block; and determining a motion vector of the current block included in the first layer image by using the obtained motion vector.