An audio encoder and decoder use architectures and techniques that improve the efficiency of quantization (e.g., weighting) and inverse quantization (e.g., inverse weighting) in audio coding and decoding. The described strategies include various techniques and tools, which can be used in combination or independently. For example, an audio encoder quantizes audio data in multiple channels, applying multiple channel-specific quantizer step modifiers, which give the encoder more control over balanc...

A system for quantizing signals having a transmitter section and a receiver section interconnected by a transmission path. The transmitter section includes a quantizer, a difference producer, and a filter. An input signal is differenced with a feedback signal, filtered and quantized to produce a first quantized output signal. The first quantized output signal is filtered to produce the feedback signal. The filtered difference signal is further differenced with the quantized output signal to prod...

A quantization apparatus for quantizing and word length limiting digitized stereo input signals including a stereo dither signal generating unit for generating stereo dither signals synthesized from at least two distinct dither signals not correlated to each other at an arbitrary ratio, a first addition unit for adding one of the stereo dither signals to one of the digital stereo input signals, a second addition unit for adding the other of the stereo dither signals to the other of the digital s...

A rate control algorithm for an MPEG-2 compliant encoder is described. The rate control algorithm has embodiments useful for constant bit rate and variable bit rate encoding. In particular, the invention relates to adaptive quantization.

Improved method and apparatus for vector quantization (VQ) to build a codebook for the compression of data. The codebook or "tree" is initialized by establishing N initial nodes and creating the remainder of the codebook as a binary codebook. Children entries are split upon determination of various attributes, such as maximum distortion, population, etc. Vectors obtained from the data are associated with the children nodes, and then representative children entries are recalculated. This splittin...

An apparatus for compensating for a quantization error has a time detector circuit for detecting a time signal on the basis of the number of clock signals occurring within the period of such time signal, a quantization error detector circuit for generating a quantization error time signal corresponding to a time difference between the time signal and the clock signal and being in the form of an analog voltage value, and a compensator circuit for compensating a digital detected time derived from ...

An apparatus for compressing and decompressing speech signals. The encoder or decoder comprises a plurality of codebooks each controlling a plurality of indexed code vectors for a different frequency band. Each of the codebooks is provided with a synthesis filter for reproducing a signal wave shape based on a code vector provided by the corresponding codebook. The encoder or decoder further comprises an adder for computing a sum of signal wave shapes reproduced by the synthesis filters. This arr...

Indicated as hybrid D-PCM a new transmission system is given which is based on differential pulse code modulation (DPCM) with signal compression at the transmitter end and signal expansion at the receiver end. In the transmitter defined auxiliary information is fed to the DPCM code groups to obtain composite code groups, while in the receiver a local auxiliary signal derived from a reconstruction device is subtracted in a separating device from the received composite signal. With a particularly ...

A rounding accuracy of DCT coefficients that are quantized is dynamically varied with a simple structure. As a result, an encoding noise is effectively suppressed and the picture quality is prevented from being deteriorated. DCT coefficients of which a picture signal is transformed by DCT are input to a quantizing circuit 30. The quantizing circuit 30 quantizes the DCT coefficients with a quantizer matrix and supplies the quantized DCT coefficients to a multiplying device 33 through an absolute ...

A method and apparatus for an adaptive quantization control is disclosed. The present invention decomposes one picture into a plurality of blocks, encodes the picture in the block unit and controls quantization by obtaining a first activity from a comparison of the activity of the current block to be encoded and that of the entire blocks; obtaining a second activity from a comparison of motions of neighboring blocks; and controlling the quantization using the first activity if the first activity...