Abstract: A quantizer and dequantizer for use in a video coding system that applies non linear, piece-wise linear scaling functions to video information signals based on a value of a variable quantization parameter. The quantizer and dequantizer apply different non linear, piece-wise linear scaling functions to a DC luminance signal, a DC chrominance signal and an AC chrominance signal. A code for reporting updates of the value of the quantization parameter is interpreted to require larger changes when the quantization parameter initially is large and smaller changes when the quantization parameter initially is small.

Abstract: A predictive video coder performs gradient prediction based on previous blocks of image data. For a new block of image data, the prediction determines a horizontal gradient and a vertical gradient from a block diagonally above the new block (vertically above a previous horizontally adjacent block). Based on these gradients, the encoder predicts image information based on image information of either the horizontally adjacent block or a block vertically adjacent to the new block. The encoder determines a residual that is transmitted in an output bitstream. The decoder performs the identical gradient prediction and predicts image information without need for overhead information. The decoder computes the actual information based on the predicted information and the residual from the bitstream.

Abstract: Audiovisual data storage is enhanced using an expanded physical object table utilizing an ordered list of unique identifiers for a particular object for every object instance of an object contained in segments of a data file. Two object instances of the same object in the same segment have different object identifiers. Therefore, different instances of the same object use different identification and the different object instances may be differentiated from one another for access, editing and transmission. The necessary memory required for randomly accessing data contained in files using the expanded physical object table may be reduced by distributing necessary information within a header of a file to simplify the structure of the physical object table. In this way, a given object may be randomly accessed by means of an improved physical object table/segment object table mechanism.

Abstract: A technique for implicitly encoding shape information by using a chroma-key color. A bounding box is created enclosing the video object. The bounding box is extended to be of size of next integer multiple of macroblock size and divided into a plurality of macroblocks. For each boundary macroblock, each pixel outside the object is replaced with the chroma-key color to implicitly encode shape information. Pixel data for boundary macroblocks and macroblocks inside the object are DCT transformed, scaled and motion compensated. A finer quantizer (smaller quantizer) is used for boundary macroblocks to improve image quality. A first_shape_code can be used to identify each macroblock as either 1) inside the object; 2) outside the object; or 3) on the object boundary. To improve data compression and achieve low complexity shape extraction with DCT and motion compensation, a first_shape_code is sent for all macroblocks, and only macroblocks that are inside the object or on the object boundary are coded.

Abstract: Audiovisual data storage is enhanced using an expanded physical object table utilizing an ordered list of unique identifiers for a particular object for every object instance of an object contained in segments of a data file. Two object instances of the same object in the same segment have different object identifiers. Therefore, different instances of the same object use different identification and the different object instances may be differentiated from one another for access, editing and transmission. The necessary memory required for randomly accessing data contained in files using the expanded physical object table may be reduced by distributing necessary information within a header of a file to simplify the structure of the physical object table. In this way, a given object may be randomly accessed by means of an improved physical object table/segment object table mechanism.

Abstract: A video coding system that codes video objects as scalable video object layers. Data of each video object may be segregated into one or more layers. A base layer contains sufficient information to decode a basic representation of the video object. Enhancement layers contain supplementary data regarding the video object that, if decoded, enhance the basic representation obtained from the base layer. The present invention thus provides a coding scheme suitable for use with decoders of varying processing power. A simple decoder may decode only the base layer of video objects to obtain the basic representation. However, more powerful decoders may decode the base layer data of video objects and additional enhancement layer data to obtain improved decoded output. The coding scheme supports enhancement of both the spatial resolution and the temporal resolution of video objects.

Abstract: A technique for implicitly encoding shape information by using a chroma-key color. A bounding box is created enclosing the video object. The bounding box is extended to be of size of next integer multiple of macroblock size and divided into a plurality of macroblocks. For each boundary macroblock, each pixel outside the object is replaced with the chroma-key color to implicitly encode shape information. Pixel data for boundary macroblocks and macroblocks inside the object are DCT transformed, scaled and motion compensated. A finer quantizer (smaller quantizer) is used for boundary macroblocks to improve image quality. A first_shape_code can be used to identify each macroblock as either 1) inside the object; 2) outside the object; or 3) on the object boundary. To improve data compression and achieve low complexity shape extraction with DCT and motion compensation, a first_shape_code is sent for all macroblocks, and only macroblocks that are inside the object or on the object boundary are coded.

Abstract: The invention provides a system and method allowing the adaptation of a nonadaptive system for playing/browsing coded audiovisual objects, such as the parametric system of MPEG-4. The system of the invention is referred to as the programmatic system, and incorporates adaptivity on top of the parametric system. The parametric system of MPEG-4 consists of a Systems Demultiplex (Demux) overseen by digital media integration framework (DMIF), scene graph and media decoders, buffers, compositer and renderer. Adaptations possible with the invention include interfaces in the categories of media decoding, user functionalities and authoring, thus allowing a number of enhanced functionalities in response to use input as well as graceful degradation in response to limited system resources. The invention includes a specification of an interfacing method in the form of an application programming interface (API). Hot object, directional, trick mode, transparency and other interfaces are specified.

Abstract: The invention provides a system and method for processing object-based audiovisual information which is capable of flexibly encoding, storing and accessing a variety of data objects. Audiovisual objects, illustratively prepared in MPEG-4 format, are stored onto physical media using file consisting of segments and access layer primary data units (PDUs), which are accessed using index information. The processes of encoding, storing and accessing audiovisual information are decoupled from monolithic storage in a strict linear order, and reordering and other editorial manipulations are possible.

Abstract: The invention provides a standardized interface facility for MPEG-4 authoring, bitstream manipulation, editing and interpretation, with associated tools and interfaces to, resulting in coded bitstreams which are easier to test, check and debug while conforming to the MPEG-4 standard. The specified interfaces can also facilitate graceful degradation in the face of decreased resources by allowing editing of bitstreams. The specified interfaces can also allow creation of decodable bitstreams in response to the user requests either directly or indirectly embedded in audiovisual applications, as well as future services. The invention specifies a bitstream input/output package in the Java programming language to facilitates bitstream encoding and decoding of audio-visual media objects, especially when coding uses the MPEG-4 standard.