International Business Machines Corporation

Conexant Systems, Inc.

Eric Viscito

Cesar Augusto Gonzales

Prasoon Tiwari

Dzung Tien Hoang

Elliot N Linzer

Agnes Yee Ngai

Dov Ramm

Charlene Ann Gebler

Heidi Aarlien Peterson

Zhijun Tong

Cecelia L Dopp

In one aspect, a method for encoding pictures is provided. The method is applied to each picture in a sequence of pictures, and the method comprises the steps of assigning a pre-decoder buffer removal time to the picture; selecting, for the picture, a number of bits, wherein the time-equivalent of the number of bits is no greater than a difference based on the pre-decoder buffer removal time of the picture and an initial arrival time of the picture into a pre-decoder buffer; and compressing the picture to generate the number of bits. The method may further include the step of allocating a first number of bits for compressing the picture and one or more number of bits for compressing one or more future pictures, wherein the future pictures are in the pre-decoder buffer at the pre-decoder buffer removal time of the current picture.

Hypothetical reference decoder with low start-up delays for compressed image and video

One method for analyzing a bitstream having a plurality of compressed pictures comprises computing an initial arrival time and a final arrival time of a compressed picture, wherein the initial arrival time is equal to an earlier of the final arrival time of the immediately previous compressed picture or equal to a sum of a fixed time plus a sum of removal delays of all of the compressed pictures between the first compressed picture following the buffering period message and the compressed picture, including the compressed picture, and wherein the final arrival time is equal a sum of the initial arrival time and a time calculated based on the number of bits associated with the compressed picture at the bit rate; and verifying that a difference between the final removal time and the initial arrival time does not exceed the time for reaching the buffer size at the bit rate.

Hypothetical reference decoder for compressed image and video

A video quantizer provides for performing quantization adaptively in accordance with perceptual masking characteristics of the human visual system. In a preferred MPEG encoder-IC, a block-based activity quantization modification or &ldquo;activity-modification&rdquo; is formed from the combined correlation of block-energy and edge analyses. A luminance-sensitivity modification is then formed and correlated with the activity modification to form an intermediate modification. A nominal-quantization modification is further formed and correlated with the intermediate modification, which is then limited and correlated with a nominal quantization value to form a base modification. Next, a positional-sensitivity modification is formed as a perimeter offset, which offset is correlated with the base modification to form a modified quantization value, and which modified quantization value is then rounded and returned to a rate controller.

Apparatus and methods for adaptive digital video quantization

The invention supports visual fast-forward play and rewind at multiple speeds using a single ancillary data stream. The storage required by this data stream is approximately the same as the storage required by a single ancillary data stream used in conventional single speed fast-forward and rewind schemes. The method of the invention includes the following steps. A bitstream of the original sequence of MPEG compressed pictures is stored for normal play. Then a sub-sequence of the original sequence, consisting of every n-th picture, is compressed as I-pictures, while ensuring that all pictures in the compressed stream have equal numbers of bits. This is the ancillary stream. A client request for fast-forward play is responded to by transmitting a subset of I-pictures from the ancillary stream. A fast-reverse play request is satisfied in the same manner except that the I-frames are transmitted in the reverse order.

Multiple speed fast forward/rewind compressed video delivery system

A system and method of using multiple processors to perform video compression is provided. A video sequence is partitioned into subsequences and processing assignments for the subsequences are distributed among a plurality of processors. A picture type is then determined for each picture in each subsequence and the encoding complexity of each picture is modeled, based on the picture type. Based on the modeling, a number of bits is allocated to each picture. Each picture is then compressed in accordance with the bits allocated. Another aspect provides for encoding of pictures in a video sequence using dynamic modeling of the encoding complexity of future pictures in the video sequence. Bits are allocated to the encoding of a current picture in the video sequence based on the dynamic model. The current picture is then encoded based on the bits allocated.

Video compression using multiple computing agents

A system and methods for implementing a video encoder which for each picture guarantees that the number of bits produced will not exceed a limit. In a preferred embodiment, the system includes two cooperating components or subsystems that together with other components of a video encoder operate to encode the input video, detect when the limit on the number of bits produced so far is close to exceeding the limit on the number of bits that may be produced and reduce the bit rate when such a condition is detected. One aspect of the current invention embodies a macroblock (MB) bit stream generator that can operate in a 'low bit rate mode' Another aspect embodies a subsystem for detecting when the number of bits in the picture is close to exceeding the limit.

Motion video compression system with guaranteed bit production limits

A system and method for repeat field detection for use in rate conversion and video encoding of the type contemplated by the MPEG standards. Before encoding a frame, first field in the current frame is compared to the previously occurring field of the same parity. Next, a single number (the inter-field parameter) is generated, which is a measure of the difference between the two fields. If the inter-field parameter is below a threshold a signal is generated to indicate that the current field is a repeat of the previous field of the same parity. Otherwise, the signal is generated to indicate that the field is not a repeat of the previous field of the same parity (i.e. the field likely contains at least one small area of motion).

Methods for repeated field detection

A system and method for processing a stream of video image data so as to create a video representation that multiplexes data corresponding to resolution or bitstream scales. This representation is such that the identity of the basic MacroBlock (MB) structure of the MPEG-1 ISO standard is preserved across all resolution and bitstream scales, e.g. by scaling across four levels of resolution. A MacroBlock is associated with a series of attributes which contribute to the amount of overhead data incorporated in an MPEG-1 compressed data stream, so that by preserving the MacroBlock identify across multiple resolutions and bitstream scales, these scales can share this overhead, thus requiring it to be included only once in the data stream. Preserving the MacroBlock identify also simplifies significantly the derivation of motion estimation vector data for all resolution scales other than the highest resolution. Essentially, the motion vector data corresponding to any resolution scales can be derived from the highest resolution motion vector by appropriately scaling it down. Alternatively, the full resolution motion vectors can be derived by appropriate scale up of lower resolution motion vectors. Further, the methodology for coding a MacroBlock is also preserved.

Motion video compression system with multiresolution features

An apparatus and method for encoding of a video picture is disclosed. The video picture has a plurality of pictures. The pictures each have a plurality of macroblocks. The macroblocks each have a plurality of sub-blocks. The apparatus comprising a first module configured to generate a transform coefficient C.sub.ij for each of the sub-blocks of the macroblock. The apparatus further comprises a second module configured to variably quantize the transform coefficient by a scaling factor Q.sub.p based on the complexity of the picture and any rate control requirements.

Apparatus and method for motion video encoding employing an adaptive

A system and method are disclosed for implementing an encoder suitable for use with the proposed ISO/IEC MPEG standards including three cooperating components or subsystems that operate to variously adaptively pre-process the incoming digital motion video sequences, allocate bits to the pictures in a sequence, and adaptively quantize transform coefficients in different regions of a picture in a video sequence so as to provide optimal visual quality given the number of bits allocated to that picture.

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San Francisco, CA, United States of America

Eric Viscito