A multimedia file and methods of generating, distributing and using the multimedia file are described. Multimedia files in accordance with embodiments of the present invention can contain multiple video tracks, multiple audio tracks, multiple subtitle tracks, a complete index that can be used to locate each data chunk in each of these tracks and an abridged index that can enable the location of a subset of the data chunks in each track, data that can be used to generate a menu interface to access the contents of the file and ‘meta data’ concerning the contents of the file. Multimedia files in accordance with several embodiments of the present invention also include references to video tracks, audio tracks, subtitle tracks and ‘meta data’ external to the file.

The present invention relates to a method for encoding and decoding a quantized matrix and an apparatus using same, the method for encoding a quantized matrix according to the present invention comprising the steps of: determining a quantization matrix to be used for quantization and quantizing; determining the prediction method used for the quantization of the quantization matrix; and encoding quantization matrix information on the basis of the determined prediction method, wherein the prediction method can be either a prediction method between coefficients in the quantization matrix or a duplicate of the quantization matrix.

A subblock-based coding of transform coefficient blocks of the enhancement layer is rendered more efficient. To this end, the subblock subdivision of the respective transform coefficient block is controlled on the basis of the base layer residual signal or the base layer signal. In particular, by exploiting the respective base layer hint, the subblocks may be made longer along a spatial frequency axis transverse to edge extensions observable from the base layer residual signal or the base layer signal.

Methods and apparatus are provided for determining quantization parameter predictors from a plurality of neighboring quantization parameters. An apparatus includes an encoder for encoding image data for at least a portion of a picture using a quantization parameter predictor for a current quantization parameter to be applied to the image data. The quantization parameter predictor is determined using multiple quantization parameters from previously coded neighboring portions. A difference between the current quantization parameter and the quantization parameter predictor is encoded for signaling to a corresponding decoder.

The present invention relates to a method of decoding a video bitstream, the method comprising the steps of: receiving a bitstream representing: residual samples produced by subtracting encoder filtered motion compensated prediction samples from image samples; and motion vectors used in forming the motion compensated prediction samples; the encoder filtering process conducted on the motion compensated prediction samples at an encoder having at least one parameter; using said motion vectors to provide motion compensated prediction samples from a previously reconstructed image; decoder filtering said motion compensated prediction samples in accordance with said at least one parameter; and adding said filtered motion compensated prediction samples to said residual samples to reconstruct images. A system and apparatus corresponding to this method are also disclosed.

The present invention relates to a method for encoding and decoding a quantized matrix and an apparatus using same, the method for encoding a quantized matrix according to the present invention comprising the steps of: determining a quantization matrix to be used for quantization and quantizing; determining the prediction method used for the quantization of the quantization matrix; and encoding quantization matrix information on the basis of the determined prediction method, wherein the prediction method can be either a prediction method between coefficients in the quantization matrix or a duplicate of the quantization matrix.

A video encoder may be configured to apply a multi-stage quantization process, where residuals are first quantized using an effective quantization parameter derived from the statistics of the samples of the block. The residual is then further quantized using a base quantization parameter that is uniform across a picture. A video decoder may be configured to decode the video data using the base quantization parameter. The video decoder may further be configured to estimate the effective quantization parameter from the statistics of the decoded samples of the block. The video decoder may then use the estimated effective quantization parameter for use in determining parameters for other coding tools, including filters.

The present disclosure provides a method and apparatus for Local Illumination Compensation (LIC) for inter-prediction that uses a MinMax method to derive linear model parameters for the LIC. Values of parameters α and β for the linear model of the LIC are derived, based on reconstructed neighboring samples of the current block and reconstructed neighboring samples of the reference block. When a condition for the value of β is met, the value of α is clipped based on the value of β and the value of β is updated based on the clipped value of α before updating the inter-predicted sample values for the current block.

A video encoder may be configured to apply a multi-stage quantization process, where residuals are first quantized using an effective quantization parameter derived from the statistics of the samples of the block. The residual is then further quantized using a base quantization parameter that is uniform across a picture. A video decoder may be configured to decode the video data using the base quantization parameter. The video decoder may further be configured to estimate the effective quantization parameter from the statistics of the decoded samples of the block. The video decoder may then use the estimated effective quantization parameter for use in determining parameters for other coding tools, including filters.

According to a first aspect, a method is provided. The method includes obtaining an M×N array of pixel values an image; determining a weight selection value for position x,y in the M×N array; and using the weight selection value to obtain a weight value for use in a filter for filtering the image. Determining the weight selection value for position x,y (omega.sub.x,y) includes: a) retrieving a previously determined weight selection value for position x,y−1 (omega.sub.x,y−1); b) retrieving a previously determined alpha value (a) for position x,y−1; c) calculating a delta value (d); and d) calculating omega.sub.x,y=omega.sub.x,y−1−a+d. Calculating d includes: i) retrieving a first previously determined value (omega_row); i) retrieving a second previously determined value (alpha_row); and ii) calculating d=omega_row−alpha_row+abs(A.sub.x+1,y+1−A.sub.x+1,y+2), wherein A.sub.x+1,y+1 is the value stored in position x+1,y+1 of the array and A.sub.x+1,y+2 is the value stored in position x+1,y+2 of the array.