Matsushita Electric Industrial Co., Ltd.

Mitsubishi Electric Research Laboratories, Inc.

Mitsubishi Electric Research Labs.

Mitsubishi Denki Kabushiki Kaisha

Interdigital Vc Holdings, Inc.

Peng Yin

Anthony Vetro

Xiaoan Lu

Huifang Sun

Bede Liu

Hong Heather Yu

Tommy C Poon

A method and system reduces the spatial resolution of a compressed bitstream of a sequence of frames of a video signal by first decoding the frames, and storing the decoded frames in a first frame buffer. While performing the decoding, motion compensating is performed with full resolution motion vectors of the stored decoded frames. The decoded frames are then down-sampled to a reduced resolution, and stored in a second frame buffer. The reduced resolution frames are partially encoded to produce a reduced resolution compressed bitstream of the video. While performing the partial encoding, motion compensation is performed with reduced resolution motion vectors of the stored reduced resolution frames.

Video transcoder with spatial resolution reduction and drift compensation

A method compensates for drift in macroblocks of a partially decoded input bitstream. The macroblocks include intra-mode and inter-mode macroblocks, and each macroblock includes DCT coefficients, and at least one motion vector. An estimate of drift is measured in the partially decoded input bitstream. The estimated drift is translated into an intra refresh rate. The modes of inter-mode macroblock are mapped to intra-mode macroblock according to the refresh rate. The DCT coefficients and the motion vector for each changed macroblock are modified in accordance with the mapping for each changed macroblock.

Video transcoder with drift compensation

Signature information, representing important content of the data, is extracted from a first data block and then embedded in a different block. Data hiding techniques are used to minimize perception of the hidden data. Thereafter, if the first data block is lost or damaged during communication, the hidden data is extracted from the other data block and used to reconstruct the lost or damaged block. If desired, the signature information can be used along with information obtained from neighboring blocks adjacent or proximate to the lost or damaged block.

Data hiding in communication

The semi-fragile watermark comprises a fragile watermark component and a robust watermark component. Features are extracted from the video stream and subsequent hashing and encryption processes are performed to generate the fragile watermark. The fragile watermark includes control data information at the block level as well as frame and group level information. The fragile watermark is added on top of the robust watermark, giving the system the ability to detect alteration at the block level as well as the group level. The resulting semi-fragile watermark has the advantage of being both sensitive to malicious attack while being robust enough to survive bit rate reduction and other types of manipulation typically performed on digital multimedia signals.

Semi-fragile watermarking system for MPEG video authentication

A method transcodes groups of macroblocks of a partially decoded input bitstream. The groups of macroblocks include intra-mode and inter-mode macroblocks. Each macroblock includes DCT coefficients, and at least one motion vector. The modes of each group of macroblocks are mapped to be identical only if there is an inter-mode block and an intra-mode macroblock in the group. If any of the macroblocks in the group are mapped, then the DCT coefficients and the motion vector for such mapped macroblocks are modified in accordance with the mapping to generate reduced-resolution macroblock for an output compressed bitstream to compensate for drift.

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Princeton, NJ, United States of America

Peng Yin