Apple Inc.

Other

Thomas Pun

Hsi-Jung Wu

Xiaochun Nie

Roger Kumar

Hsi Jung Wu

Xin Tong

Maynard J Handley

Barin Geoffry Haskell

Adriana Dumitras

Paul S Chang

Jim Normile

Hyeonkuk Jeong

James O Normile

Xiaojin Shi

David William Singer

Method For Implementing A Quantizer In A Multimedia Compression And Encoding System is disclosed. In the Quantizer system of the present invention, several new quantization ideas are disclosed. In one embodiment, adjacent macroblocks are grouped together into macroblock groups. The macroblock groups are then assigned a common quantizer value. The common quantizer value may be selected based upon how the macroblocks are encoded, the type of macroblocks within the macroblock group (intra-blocks or inter-blocks), the history of the motion vectors associated with the macroblocks in the macroblock group, the residuals of the macroblocks in the macroblock group, and the energy of the macroblocks in the macroblock group. The quantizer value may be adjusted in a manner that is dependent on the current quantizer value. Specifically, if the quantizer value is at the low end of the quantizer scale, then only small adjustments are made. If the quantizer value is at the high end then larger adjustments may be made to the quantizer. Finally, in one embodiment, the quantizer is implemented along with an inverse quantizer for efficient operation.

Method for implementing a quantizer in a multimedia compression and encoding system

A method for decoding a compressed video data sequence containing one or more coded pixel blocks. The compressed video sequence is buffered. Prediction information for each of the coded pixel blocks is reviewed. One or more groups of coded pixel blocks are formed based on the reviewed prediction information such that the coded pixel blocks within a given group have similar prediction dependencies and/or at least do not depend on a reconstructed pixel within a group of received pixel blocks to enable parallel decoding. The formed groups are scheduled for processing and subsequently decoded to produce a decoded video data sequence.

Region-based processing of predicted pixels

Scalable video coding and multiplexing compatible with non-scalable decoders is disclosed. In some embodiments, video data is received and encoded in a manner that renders at least a base layer to be compatible with a non-scalable video encoding standard, including by assigning for at least the base layer default values to one or more scalability parameters. In some embodiments, video data is received and encoded to produce an encoded video data that includes a base layer that conforms to a non-scalable video encoding standard and one or more subordinate non-scalable layers, which subordinate non-scalable layers do not by themselves conform to the non-scalable video encoding standard but which can he combined with the base layer to produce a result that does conform to the non-scalable video encoding standard, such that the result can be decoded by a non-scalable decoder. An identification data identifying those portions of the encoded video data that are associated with a subordinate non-scalable layer is included in the encoded video data.

Scalable video coding/multiplexing compatible with non-scalable decoders

Scalable video coding and multiplexing compatible with non-scalable decoders is disclosed. In some embodiments, video data is received and encoded in a manner that renders at least a base layer to be compatible with a non-scalable video encoding standard, including by assigning for at least the base layer default values to one or more scalability parameters. In some embodiments, video data is received and encoded to produce an encoded video data that includes a base layer that conforms to a non-scalable video encoding standard and one or more subordinate non-scalable layers, which subordinate non-scalable layers do not by themselves conform to the non-scalable video encoding standard but which can be combined with the base layer to produce a result that does conform to the non-scalable video encoding standard, such that the result can be decoded by a non-scalable decoder. An identification data identifying those portions of the encoded video data that are associated with a subordinate non-scalable layer is included in the encoded video data.

Techniques for encoding data based at least in part upon an awareness of the decoding complexity of the encoded data and the ability of a target decoder to decode the encoded data are disclosed. In some embodiments, a set of data is encoded based at least in part upon a state of a target decoder to which the encoded set of data is to be provided. In some embodiments, a set of data is encoded based at least in part upon the states of multiple decoders to which the encoded set of data is to be provided.

Complexity-aware encoding

A method of encoding a sequence of video images is described. The method receives the sequence of video images. The method iteratively examines different encoding solutions for the sequence of video images to identify an encoding solution that optimizes image quality while meeting a target bit rate and satisfying a set of constraints regarding flow of encoded data through an input buffer of a hypothetical reference decoder for decoding the encoded video sequence. The iterative examining includes, for each encoding solution, determining whether the hypothetical reference decoder underflows while processing the encoding solution for any set of images within the video sequence.

Multi-pass video encoding solution for buffer underflow

This invention is directed to a method for decoding coded video data in which decoder performance is regulated based on perceptual masking. The method includes, upon receipt of coded video data, applying the coded video data to a multi-stage decoding process; computing perceptual masking measures for the coded video data; and switching a stage of the decoding process to a lower performance level based on the computed perceptual masking measures. The method may be applied to non-reference frames and reference frames with low numbers of dependent frames. The method provides scalability among decoders to allow for various decoder and/or coded data complexity.

Regulation of decode-side processing based on perceptual masking

A method for encoding a first set of pixels in a first image in a sequence of images is described. From a set of encoding modes, the method selects a first mode for encoding the first set of pixels. The method then determines whether encoding the first set of pixels in the first mode satisfies a set of quality criteria. The method foregoes encoding the first set of pixels in a second mode from the set of encoding modes, when the first mode encoding satisfies the set of quality criteria. The method also provides a video encoding method that examines several different methods for encoding a set of pixels in a first image. From a list of possible encoding modes, the method eliminates a set of encoding modes that are not likely to provide a suitable encoding solution. The method then examines different encoding solutions based on the remaining encoding modes in the list.

Encoding mode pruning during video encoding

Some embodiments of the invention encode a sequence of video images based on 'visual masking' attributes of the video images and/or portions of the video images. Visual masking of an image or a portion of the image is an indication of how much coding artifacts can be tolerated in the image or image portion. To express the visual masking attribute of an image or an image portion, some embodiments compute a visual masking strength that quantifies the brightness energy of the image or the image portion. In some embodiments, the brightness energy is measured as a function of the average luma or pixel energy of the image or image portion.

Encoding with visual masking

A method for encoding video with a two-dimensional (2D) transform separable to two one-dimensional (1D) transforms. The method receives an array of values for a sub-section of an image, performs a first 1D-transform of the array, transposes the resulting array, and performs a second 1D-transform of the array resulting from the transpose. The method, without performing another transpose, generates a data stream using a transposed scan order based on the values of the array resulting from the second transform. A method for decoding video encoded by a 2D transform, which separable to two 1D transforms. The method receives a data stream containing encoded values for an image, parses out the values into an array using a transposed scan order, performs a first 1D-inverse transform on the array, transposes the resulting array, and performs a second 1D-inverse transform of the array resulting from the transpose to produce a decoded output.

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San Jose, CA, United States of America

Thomas Pun