A decoder which can detect errors in MPEG-2 coefficient blocks can identify syntactically-correct blocks which have out-of-bounds coefficients. The decoder computes coefficient bounds based on quantization scalers and quantization matrices and compares these to coefficient blocks during decoding; if a block has out-of-bounds coefficients, concealment is performed on the block. In a decoder implemented all in software, coefficient bounds checking is performed on iDCT coefficients against upper and lower bounds in a spatial domain. In a decoder which performs iDCT in hardware, DCT coefficients are compared to an upper energy bound.

A decoder which can detect errors in MPEG-2 coefficient blocks can identify syntactically-correct blocks which have out-of-bounds coefficients. The decoder computes coefficient bounds based on quantization scalers and quantization matrices and compares these to coefficient blocks during decoding; if a block has out-of-bounds coefficients, concealment is performed on the block. In a decoder implemented all in software, coefficient bounds checking is performed on iDCT coefficients against upper and lower bounds in a spatial domain. In a decoder which performs iDCT in hardware, DCT coefficients are compared to an upper energy bound.

A sampling filter process is provided for scalable video coding. The process provides for re-sampling using video data Obtained from an encoder or decoder process of a base layer (BL) in a multi-layer system using adaptive phase shifting to improve quality in Scalable High efficiency Video Coding (SHVC). In order to compensate for phase offsets introduced by, downsampling an appropriate phase offset adjustment is made for upsampling in SHVC with an appropriate offset included for proper luma/chroma color space positions. In one approach the luma/chroma phase offset is specified and a filter is selected to apply the appropriate phase change.

A sampling filter process is provided for scalable video coding. The process provides for re-sampling using video data Obtained from an encoder or decoder process of a base layer (BL) in a multi-layer system using adaptive phase shifting to improve quality in Scalable High efficiency Video Coding (SHVC). In order to compensate for phase offsets introduced by, downsampling an appropriate phase offset adjustment is made for upsampling in SHVC with an appropriate offset included for proper luma/chroma color space positions. In one approach the luma/chroma phase offset is specified and a filter is selected to apply the appropriate phase change.

Disclosed is an image data encoding/decoding method and apparatus. A method for decoding a 360-degree image comprises the steps of: receiving a bitstream obtained by encoding a 360-degree image; generating a prediction image by making reference to syntax information obtained from the received bitstream; combining the generated prediction image with a residual image obtained by dequantizing and inverse-transforming the bitstream, so as to obtain a decoded image; and reconstructing the decoded image into a 360-degree image according to a projection format.

Disclosed is an image data encoding/decoding method and apparatus. A method for decoding a 360-degree image comprises the steps of: receiving a bitstream obtained by encoding a 360-degree image; generating a prediction image by making reference to syntax information obtained from the received bitstream; combining the generated prediction image with a residual image obtained by dequantizing and inverse-transforming the bitstream, so as to obtain a decoded image; and reconstructing the decoded image into a 360-degree image according to a projection format.

Systems, methods, and instrumentalities are disclosed for discontinuous face boundary filtering for 360-degree video coding. A face discontinuity may be filtered (e.g., to reduce seam artifacts) in whole or in part, for example, using coded samples or padded samples on either side of the face discontinuity. Filtering may be applied, for example, as an in-loop filter or a post-processing step. 2D positional information related to two sides of the face discontinuity may be signaled in a video bitstream so that filtering may be applied independent of projection formats and/or frame packing techniques.

A method and wearable camera for encoding video captured by a wearable camera determines a centre of rotation for an image frame to be encoded. The centre of rotation relates to a rotation of the wearable camera at the time of capturing the video and the image frame comprises multiple groups of pixels. Furthermore, compression levels are set for the multiple groups of pixels of the image frame. The compression levels for the multiple groups of pixels of the image frame are set such that a level of compression increases with a radial distance from the centre of rotation. The image frame is encoded using the compression levels.

A method and wearable camera for encoding video captured by a wearable camera determines a centre of rotation for an image frame to be encoded. The centre of rotation relates to a rotation of the wearable camera at the time of capturing the video and the image frame comprises multiple groups of pixels. Furthermore, compression levels are set for the multiple groups of pixels of the image frame. The compression levels for the multiple groups of pixels of the image frame are set such that a level of compression increases with a radial distance from the centre of rotation. The image frame is encoded using the compression levels.

Block based decoder configured to partition a picture (10) of more than one color component (10.sub.1, 10.sub.2) and of a color sampling format, according to which each color component (10.sub.1, 10.sub.2) is equally sampled, into blocks using a partitioning scheme according to which the picture (10) is equally partitioned with respect to each color component (10.sub.1, 10.sub.2). Additionally, the block based decoder is configured to decode a first color component (10.sub.1) of the picture (10) in units of the blocks with selecting, for each of intra-predicted first color component blocks (18′.sub.11-18′.sub.1n) of the picture (10), one out of a first set (508) of intra-prediction modes. The first set (508) comprises matrix-based intra prediction modes (510.sub.1 to 510.sub.m) according to each of which a block inner (18) is predicted by deriving a sample value vector (514) out of references samples (17), neighboring the block inner (18), computing a matrix-vector product (512) between the sample value vector (514) and a prediction matrix (516) associated with the respective matrix-based intra prediction mode (510i to 510.sub.m) so as to obtain a prediction vector (518), and predicting samples in the block inner (18) on the basis of the prediction vector (518). Additionally, the block based decoder is configured to decode a second color component (10.sub.2) of the picture (10) in units of the blocks by intra-predicting a predetermined second color component block (18.sub.2) of the picture using the matrix-based intra prediction mode selected for a co-located intra-predicted first color component block (18.sub.1).