Motorola Corporation

Codex Corporation

Mei Yong

M Vedat Eyuboglu

Jian Yang

Dennis Ng

Qin-Fan Zhu

Oin-Fan Zhu

The present invention provides a device, method, and system for, in an entry node of a packet communication network, transcoding a received constant bit-rate video bitstream to a variable bit-rate video bitstream, packetizing the variable bit-rate video bitstream into video packets for efficient transport of a video signal over a packet-switched network.

Device, method and system for variable bit-rate packet video

The present invention provides a method (900) and device (100) in multimedia communication systems for efficiently segmenting information bitstreams from multiple media sources into variable length packets, and multiplexing and sending the packets to a shared communication link with low delay and low overhead. The packet segmentation and multiplexing are performed dynamically based on fullness of a set of information buffers that contain the information bitstreams to be transmitted, and delay-sensitivity of each information bitstreams. The multi-discipline queuing scheme has been developed in this invention to control the dynamic packet segmenting and multiplexing process.

Multimedia multiplexing device and method using dynamic packet

The present invention provides a transcoder for transcoding of digitally encoded bit streams produced by predictive encoders. The transcoder of this invention is less complex than previously known transcoders in terms of both computational and storage requirements. This efficiency is achieved by combining decoding and re-encoding steps into one step. This one-step transcoding is accomplished by modifying the originally quantized vectors and then requantizing and noiseless encoding these vectors into a bit stream in accordance with a predetermined objective.

Efficient transcoding device and method

The method and device of the present invention provide a mechanism at a network node to compensate for variable delays or delay jitters of video packets transported over a packet-switched network, such as an ATM network, and generate a continuous bitstream to an external decoder. The received video packets with variable delays are first depacketized and stored in a video information buffer and then are sent to the external decoder through another constant or variable bit-rate channel. Based on a hypothetical decoder buffer verifier condition, stuffing bits are inserted into the output video bitstream to prevent the decoder buffer from overflowing. Stuffing bits are sent if one of the following two cases occurs: A) the condition of the hypothetical decoder buffer verifier is violated; B) the video information buffer is empty. A minimum number of stuffing bits are sent each time to minimize the incurred delay and concurrently make the following three conditions satisfied: 1) overflow of the decoder buffer is avoided; 2) idleness of the channel is avoided; 3) the stuffing bits must comply with the syntax of the video bitstream.

Minimum-delay jitter smoothing device and method for packet video

A priority assignment method and device are set forth for assigning a priority to a selected speech frame coded by a linear predictive coder based on at least two of: an energy of the speech frame, a log spectral distance between a frame and a frame immediately previous, and a pitch predictor coefficient for the selected speech frame. The invention protects against loss of perceptually important and hard-to-reconstruct speech frames.

Prioritization method and device for speech frames coded by a linear

A novel spectral interpolation and efficient excitation codebook search method developed for a Code-Excited Linear Predictive (CELP) speech coder is set forth. The interpolation is performed on an impulse response of the spectral synthesis filter. As the result of using this new set of interpolation parameters, the computations associated with an excitation codebook search in a CELP coder are considerably reduced. Furthermore, a coder utilizing this new interpolation approach provides noticeable improvement in speech quality coded at low bit-rates.

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Canton, MA, United States of America

Mei Yong